In my first year at work, I was involved in coal-to-natural gas projects; I hope everyone can provide me with more learning materials

Split entry: Technical term definitions for natural gas. Chinese name: Natural gas; English name: natural gas. Definition 1: A gaseous fossil fuel primarily composed of methane. It mainly exists in oil fields and gas fields, with a small amount also found in coal seams. Applied Discipline: Electrical Engineering (first-level discipline) ； Fuel (sub-discipline) Definition 2: A combustible gas extracted from underground, primarily composed of methane. It is a mixture of low-molecular-weight saturated hydrocarbon gases from the paraffin group and a small amount of non-hydrocarbon gases. Applied Discipline: Resource Technology (first-level discipline) ； Energy Resources Science (secondary discipline). The above content was approved and published by the National Committee for Terms in Science and Technology. Request assistance for an encyclopedia entry. Natural gas storage tanks: Natural gas is a gaseous fossil fuel that is primarily composed of methane. It mainly exists in oil fields and gas fields, with a small amount also found in coal seams. When burned, natural gas produces no waste residues or wastewater, and it offers advantages over energy sources such as coal and oil, including greater safety, higher calorific value, and cleaner operation. On June 22, 1991, a large natural gas field was discovered in the Shaanxi-Gansu-Ningxia Basin. On the night of September 18, 2011, the American company Noble Energy began exploring for natural gas resources in Block 12 of Cyprus’ exclusive economic zone. Table of Contents
Basic Definitions
Chemical Composition
Brief Introduction
Main Uses
Causes of Formation
Biogenic Gas
Oil-type Gas
Coal-type Gas
Inorganic Gas
Identification Marks for Different Types of Gas
Comparison with Oil
Relevant Extraction Methods
Main Distribution Areas
Main Classifications
Liquefied Natural Gas (LNG)
Liquefied Petroleum Gas (LPG)
Liquefied Coalbed Methane (HCL)
Necessity of Producing and Using Liquefied Natural Gas
Application Areas
Investment Value
Main Advantages
Environmentally Friendly
Cost-effective
Safe and Reliable
Improves Quality of Life
Safety Management
Chapter 1 General Provisions
Chapter 2 Construction of Urban Gas Projects
Chapter 3 Production, Storage, and Distribution of Urban Gas
Chapter 5 Production and Sales of Urban Gas Appliances
Chapter 6 Emergency Repair and Handling of Urban Gas Accidents
Chapter 7 Rewards and Punishments
Chapter 8 Supplementary Provisions
Basic Definitions of Domestic Gas
Chemical Composition
Brief Introduction
Main Uses
Causes of Formation
Biogenic Gas
Oil-type Gas
Coal-type Gas
Inorganic Gas
Identification Marks for Different Types of Gas
Comparison with Oil
Relevant Extraction Methods
Main Distribution Areas
Main Classifications
Liquefied Natural Gas (LNG)
Liquefied Petroleum Gas (LPG)
Liquefied Coalbed Methane (HCL)
Necessity of Producing and Using Liquefied Natural Gas
Application Areas
Investment Value
Main Advantages
Environmentally Friendly
Cost-effective
Safe and Reliable
Improves Quality of Life
Safety Management
Chapter 1 General Provisions
Chapter 2 Construction of Urban Gas Projects
Chapter 3 Production, Storage, and Distribution of Urban Gas
Chapter 5 Production and Sales of Urban Gas Appliances
Chapter 6 Emergency Repair and Handling of Urban Gas Accidents
Chapter 7 Rewards and Punishments
Chapter 8 Supplementary Provisions
Details on Domestic Gas
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Basic Definitions
In a broad sense, natural gas refers to all gases that exist naturally in the environment, including those formed through various natural processes in the atmosphere, hydrosphere, biosphere, and lithosphere. The definition of \"natural gas\" that has been commonly used for a long time is a narrow definition based on energy considerations; it refers to a mixture of hydrocarbon and non-hydrocarbon gases naturally present in geological formations. The main component is alkanes, with methane accounting for the vast majority, along with small amounts of ethane, propane, and butane. In addition, there are usually hydrogen sulfide, carbon dioxide, nitrogen, and water vapor, as well as trace amounts of inert gases such as helium and argon. Under standard conditions, methane to butane exist as gases, while those with higher molecular weights than pentane are liquids. 　　Natural gas mainly exists in oil field gas, gas field gas, coalbed methane, mud volcano gas, and biogenic gas, with a small amount also coming from coal seams. Natural gas can be further divided into associated gas and non-associated gas. Associated with crude oil, the field gas that is extracted simultaneously with the crude oil is called associated gas ； Non-associated gas includes natural gas from pure gas fields and natural gas from condensate gas fields, both of which exist in gaseous form within the strata. After the natural gas from a condensate field flows out of the wellhead, it separates into gas and liquid phases as pressure and temperature decrease. The gas phase is the natural gas from the condensate field, while the liquid phase is the condensate, also known as condensate oil. 　　 Compared to energy sources such as coal and oil, natural gas produces very few substances during combustion that can affect human respiratory health; the carbon dioxide it generates is only about 40% of that produced by coal, and the amount of sulfur dioxide produced is also minimal. When burned, natural gas produces no waste residues or wastewater, offering advantages such as safety in use, high calorific value, and cleanliness. However, with regard to the greenhouse effect, natural gas produces carbon dioxide just like coal and oil. Therefore, natural gas cannot be considered a new energy source. Edit this section: Chemical composition The main component of natural gas is methane (CH4), which is the shortest and lightest hydrocarbon molecule. It may also contain some heavier hydrocarbon molecules such as ethane (C2H6), propane (C3H8), and butane (C4H10). In addition, there are variable amounts of gaseous sulfur present; see Natural gas condensates. Organic sulfides and hydrogen sulfide (H2S) are common impurities that must be removed prior to most uses of natural gas. Natural gas with high levels of sulfur-containing impurities is described in technical terms as “sour”. Although natural gas is colorless and odorless, it is given an odor using thiols before being delivered to end-users, to aid in detecting leaks. Unlike carbon monoxide, natural gas is not toxic and is essentially harmless to humans. However, if it is present in high concentrations, reducing the amount of oxygen in the air to a level insufficient for survival, it can still be fatal, as natural gas cannot be used for human respiration. As a fuel, natural gas can also cause injuries or deaths through explosions. Although natural gas is lighter than air and tends to disperse easily, when it accumulates in enclosed spaces such as houses or tents to certain concentrations, it can trigger powerful explosions. Such explosions can destroy entire buildings and even affect nearby structures. The lower explosive limit of methane in air is 5%, while the upper limit is 15%. In natural gas engines, explosions caused by compressed natural gas do not occur spontaneously due to the volatility of the gas; therefore, external forces are needed to maintain the natural gas concentration between 5% and 15% in order to trigger an explosion. Edit this section: Brief introduction Natural gas is a multi-component mixture, with alkanes being its main components, among which methane accounts for the vast majority. There are also small amounts of ethane, propane, and butane. In addition, it generally contains hydrogen sulfide, carbon dioxide, nitrogen, and water vapor, as well as trace amounts of inert gases such as helium and argon. Under standard conditions, methane to butane exist as gases, while those below pentane are liquids. 　　 Natural gas is a gaseous hydrocarbon formed through the gradual transformation, metamorphism, and cracking of ancient biological remains that have accumulated underground. It is flammable and is often produced alongside crude oil during oil extraction in oil fields, or it can be found in natural gas fields. 　　Natural gas is stored in porous rock layers underground; its main component is methane, with a specific gravity of about 0.65, making it lighter than air. It is colorless, odorless, and non-toxic. Natural gas companies add odorants (**thiophene**) in accordance with **regulations** so that users can detect it. When the concentration of natural gas in the air reaches a certain level, it can cause suffocation. 　　If the concentration of natural gas in air is within the range of 5% to 15%, it can explode when exposed to an open flame; this concentration range is known as the explosive limit of natural gas. An explosion generates high pressure and high temperature in an instant, and its destructive power and danger are very great. 　　Based on the occurrence conditions of natural gas, it is further divided into three types: structural natural gas, water-soluble natural gas, and coal mine natural gas. Constructive natural gas can be further divided into wet natural gas produced alongside crude oil, and dry natural gas that contains no liquid components. Main uses of this section: Natural gas power generation. Natural gas power generation is an effective way to alleviate energy shortages, reduce the proportion of coal-based power generation, and minimize environmental pollution. From an economic perspective, it requires less investment per unit of installed capacity, has a shorter construction period, and results in lower electricity prices, giving it strong competitiveness. 　　Natural gas chemical industry Natural gas is the best raw material for producing nitrogen fertilizers, offering advantages such as low investment, low costs, and minimal pollution. Natural gas accounts for about 80% on average worldwide as a raw material in nitrogen fertilizer production. 　　 Major regions in the world where natural gas is available: city gas services, especially as a fuel for residential use. With the improvement of people’s living standards and the growing awareness of environmental protection, demand for natural gas has increased significantly in most cities. The economic benefits of natural gas as a domestic fuel are also greater than those of industrial fuels. 　　Compressed natural gas vehicles use natural gas instead of gasoline for vehicles, offering advantages such as lower costs, less pollution, and improved safety. 　　With increasing environmental awareness among people and a growing global demand for clean energy, countries are also reflecting this trend through legislative measures. Natural gas was once considered one of the cleanest forms of energy; coupled with the Gulf Crisis in the Middle East in 1990, this further strengthened the determination of the United States and other major oil-consuming countries to develop alternative energy sources. As a result, demand for natural gas is set to increase until true alternative energy sources are discovered. Reasons for the formation of this section: The formation processes of natural gas and oil are both related and distinct; oil is primarily formed during the deep metamorphism stage as a result of catalytic cracking, whereas the formation of natural gas occurs throughout the entire process of diagenesis, deep metamorphism, post-metamorphic changes, and even metamorphism ； Compared to the formation of oil, the formation of natural gas occurs on a wider scale, more rapidly, and more easily, whether in terms of the original materials or the environmental conditions. Various types of organic matter can give rise to natural gas – humic-type organic matter can produce both oil and gas, while humin-type organic matter primarily yields gaseous hydrocarbons. Therefore, the origins of natural gas are diverse. In summary, the origins of natural gas can be classified into biogenic gas, oil-type gas, and coal-type gas. In recent years, inorganic-origin gases, especially non-hydrocarbon gases, have received considerable attention; they are briefly introduced here as well. Finally, the methods for identifying various types of origin gases are also discussed. Biogenic gas 　　　　Concept 　　Biogenic gas refers to natural gas that is formed during the early stages of diagenesis, in the shallow biochemical zone, as a result of the microbial fermentation and synthesis of sedimentary organic matter. It sometimes contains gases formed by early low-temperature degradation. Biogenic gas occurs in rock formations with shallow burial, recent age, and low degree of evolution, and is mainly composed of methane gas. 　　Formation conditions The prerequisite for the formation of biogenic gas is an abundance of organic matter and a strongly reducing environment. 　　The organic parent material most conducive to the formation of anger is the herbaceous humus type–sludge humus type; such organic matter is commonly found in deltas and swampy lake shores where there is an abundant supply of terrestrial materials. Sandstone-shale sequences containing terrestrial organic matter are generally the most favorable. The reason why large amounts of biogenic gas cannot form in sulfuric acid-bearing strata is that sulfuric acid has a significant inhibitory effect on methanogens; H2 preferentially reduces SO42- to S2-, resulting in the formation of metal sulfides or H2S, and therefore CO2 cannot be reduced by H2 to CH4. 　　The growth of methanogens requires an appropriate geochemical environment; firstly, there must be strong reducing conditions, with an Eh value of around 98%, and in some cases even above 99%. The content of heavy hydrocarbons should be low – typically, natural gas with an 80% (by volume) concentration is suitable for use in industries such as manufacturing, agriculture, meteorology, medicine, the food industry, and environmental protection. The CO2 content in the natural gas from Well 9 in Shatouwei, the Sanshui Basin in Guangdong Province, China, is as high as 99.55%, with a daily gas production of 5 million cubic meters, making it a gas reservoir of great economic value. 　　The CO2 gas field reserves discovered so far in the world are mainly found in Mesozoic-Cenozoic volcanic areas, fault-active zones, oil and gas-rich areas, and coalfield areas. In terms of their origins, there are the following types: Inorganic origins: ① The mantle magma is rich in CO2 gas; as the magma rises along weak zones in the crust and the pressure decreases, the CO2 escapes. 　　② Carbonate rocks can produce large amounts of CO2 when exposed to high temperatures or subjected to deep metamorphism. When groundwater is involved, or when the rocks contain impurities such as Al, Mg, and Fe, a considerable amount of CO2 can be generated even at temperatures between 98 and 200°C. The characteristics of CO2 produced in this way are: a CO2 content greater than 35%, and a δ13CCO2 value of less than -8‰. 　　③ The interaction of carbonate minerals with other minerals can also produce CO2, such as when dolomite reacts with kaolinite. 　　In addition, the organic origins include: Biochemical processes Thermochemical processes Oxidation of oil fields Oxidation of coal N2 N2 is the main component of the atmosphere; studies show that the highest concentrations and fugacities of molecular nitrogen are found in nitrogen-rich strata at the edges of ancient cratons, particularly within the boundaries of areas where evaporite rocks are present. Nitrogen moves from the water layer into the gas reservoir, being derived from nitrates, with NH4+ as its precursor. 　　Reservoirs with an N2 content of over 15% are considered nitrogen-rich reservoirs. The main sources of N2 in natural gas include: ① N2 generated by the decomposition of organic matter; this process reaches its peak at temperatures of 100–130°C, and the amount of N2 produced accounts for 2.0% of the total gas generated, which is a relatively low proportion ； (organic) ② Thermal desorption of crustal rocks: For example, when diabase is thermally analyzed, the nitrogen content can reach up to 52%, and such nitrogen can be concentrated ； 　　③ Denitrification of underground brine (nitrates): Nitrates are converted into N2O+N2 through biochemical processes ； 　　④ Mantle-derived N2: Iron meteorites contain nitrogen in the range of dozens to hundreds of ppm ； 　　⑤ Atmospheric N2: N2 in the atmosphere moves deeper along with groundwater circulation, with hot spring gas being the main source of contamination. 　　From an isotopic perspective, generally, the heaviest nitrogen is concentrated in nitrate rocks, heavier nitrogen is found in aromatic hydrocarbon compounds, while lighter nitrogen is present in ammonium salts and amino acids. 　　H2S: H2S is present in almost all discovered gas reservoirs around the world. Reservoirs with an H2S content of >1% are considered H2S-rich, while those that are commercially viable require a H2S content of >5%. 　　According to research (Zhabrew et al., 1988), commercially significant H2S-enriched areas are primarily large oil and gas-bearing sedimentary basins, whose sedimentary profiles all contain thick carbonate-evaporite sequences. 　　The formation of H2S in nature mainly occurs through the following two categories: ① Biogenic (organic) sources: including biological degradation and biochemical processes ； 1 　　② Thermochemical origin (inorganic): includes thermal degradation, thermochemical reduction, high-temperature synthesis, etc. According to thermodynamic calculations, the temperature required for gypsum (CaSO4) in natural environments to be reduced to H2S by hydrocarbons is as high as 150°C; therefore, H2S-rich gas reservoirs found in nature all occur in deep carbonate-evaporite systems, where the carbonate rocks possess good reservoir properties. 　　Noble gases (He, Ar,…) Although these gases are scarce underground, due to their unique geochemical behavior, scientists often use them as tracers for geochemical processes. 　　The isotope ratios of He and Ar, namely 3He/4He and 40Ar/36Ar, are extremely important tools for determining the origin of natural gas; as one moves from atmospheric sources to crustal sources, to mixed crustal-mantle sources, and finally to mantle sources, these ratios increase continuously – the former rising from 1.39×10-6 to >10-5, while the latter rising from 295.6 to >2000. 　　Furthermore, based on the radioactive origin of Ar isotopes in the surrounding rock and gas reservoir, the formation age of the gas can also be calculated (Zhu Ming, 1990). 　　Direct reaction of gaseous carbon with hydrogen. The main point is that all elements on Earth, without exception, have gone through a process similar to nuclear fusion as occurs in the Sun today. After carbon was formed through the fusion of lighter element nuclei, it reacted with hydrogen present in the primitive atmosphere to produce methane. As temperatures dropped, oxygen became more reactive; it oxidized and polymerized methane to form oil molecules. Over time, due to further oxidation and polymerization, these oil molecules grew larger, resulting in large amounts of substance similar to asphalt. When volcanic lava frequently erupted on the early Earth, its high density caused it to sink to the bottom of the oil, isolating it from air and subjecting it to increased heat, which led to the breaking of carbon-hydrogen bonds and the release of hydrogen, thereby forming coal. (Some oil molecules are not formed by the oxidation and polymerization of methane; rather, they are created directly from carbon and hydrogen into unsaturated hydrocarbons when the temperature on Earth is high.) Identifiers for gases of various origins Natural gas is widely distributed in nature, with many different types of origins and varying degrees of thermal evolution, resulting in a wide range of geochemical characteristics; therefore, it is difficult to use uniform indicators for its identification. Practice has shown that comprehensive evaluation using multiple indicators is more reliable than using a single indicator (Dai Jinxing, 1993). The parameters involved in determining the origin of natural gas mainly include isotopes, gas components, light hydrocarbons, and biomarkers. Among these, the criteria for some parameters are absolute and definitive, while those for other parameters overlap to some extent among the three possible origins of the gas, giving them only a relative significance. Edit this paragraph to compare petroleum: Petroleum and natural gas share commonalities and similarities in terms of their elemental composition, structural form, as well as the raw materials from which they are formed and the timing of their formation; at the same time, they also have their own characteristics and differences. Natural gas vehicles, in terms of their chemical composition, feature low molecular weights for natural gas molecules (less than 20), a simple structure, a high H/C atom ratio (4–5), and significant fractionation of carbon isotopes. Oil has a high molecular weight (75–275) and a relatively complex structure; its H/C atom ratio is low (1.4–2.2), and the fractionation of carbon isotopes occurs to a lesser extent than in natural gas. 　　In terms of physical properties, natural gas is essentially a single gas phase that contains only very small amounts of liquid hydrocarbons and water ； Oil is a mixture that can contain gas, liquid, and solid phases, with the liquid phase being its characteristic form. Natural gas has a much lower density than oil, making it easy to compress as well as expand. Under standard conditions, the viscosity of natural gas is only n×10-2 to 10-3 mPa·s, whereas the viscosity of oil is n to n×10-3 mPa·s, representing a difference of several orders of magnitude. Natural gas has a greater diffusion capacity and solubility in water than oil. 　　In terms of the conditions for generation, natural gas has broader requirements than oil. Natural gas is formed both from organic matter and from deep-seated inorganic processes ； The sedimentation environment is mainly lacustrine in type ； The parent material for gas formation is primarily humic kerogen (type III), and gas generation occurs over a wide temperature range, with biogas starting to form at low temperatures in shallower layers ； In the range of moderate depths (where temperatures are generally between 65 and 90°C), during the \"liquid window\" phase in which thermal degradation of organic matter occurs, resulting in the production of large amounts of oil, other substances can also be generated as a byproduct ； Under deep-high-temperature conditions, the breakdown of organic matter primarily results in the formation of natural gas. Natural gas also has less stringent requirements for reservoirs compared to oil; reservoirs can be formed with a porosity of 10%–15% in ordinary rocks, and a permeability of 1×10-3–5×10-3 μm2 is sufficient. Due to the reactivity of natural gas, the requirements for the cap rock are much stricter than those for oil. Therefore, the areas where natural gas is found are broader than those for oil, and the types of natural gas produced as well as its storage forms are more diverse than those of oil. There are conventional natural gas reservoirs with storage patterns similar to those of oil, such as structural, stratigraphic, and lithological gas reservoirs, as well as unconventional natural gas reservoirs such as coalbed methane, water-shielded gas, gas hydrates, and shale gas from tight sandstones. Coal seams that serve both as source rocks and reservoirs for coalbed methane have become a very practical type of reservoir. 　　“Of the proven natural gas reserves in the world, about 90% are not associated with oil; instead, they exist as pure gas reservoirs or condensate gas reservoirs, forming gas-bearing zones or areas. This shows that although natural gas geology and petroleum geology share certain commonalities and are closely related, natural gas nevertheless has its own geological laws governing its formation, development, and the creation of deposits” (Bautz, 1988). 　　Due to certain properties of natural gas, it differs from oil in terms of theoretical research, resource evaluation, exploration techniques, and extraction methods; therefore, it is necessary to develop targeted working methods and technical approaches to meet the growing demands for the development of natural gas resources in the future. Edit this section on extraction. Natural gas, like crude oil, is also buried in underground geological formations; some of it is stored in the same layers as crude oil, while some exists separately. Natural gas stored in the same stratum as crude oil is extracted together with the crude oil. For those containing only single-phase gas, we call them gas reservoirs; their extraction methods are quite similar to those used for crude oil, but they also have their own particularities. Natural gas extraction: Due to its low density, at 0.75–0.8 kilograms per cubic meter, the gas column in the wellbore exerts little pressure on the bottom of the well ； Natural gas has low viscosity, resulting in low flow resistance in formations and pipelines ； Also, due to its high coefficient of expansion, its elastic energy is high as well. Therefore, natural gas is generally extracted using the self-priming method. This is basically the same as the self-priming oil production method. However, since the pressure in gas wells is generally high and natural gas is a flammable and explosive gas, the pressure resistance and sealing performance of the equipment at gas well heads are required to be much higher than those for oil well heads. 　　Natural gas extraction also has its own characteristics. Firstly, like crude oil, natural gas is often part of the same reservoir system as bottom water or edge water. As natural gas is extracted, the elastic energy of the water drives it to flow along high-permeability zones into the gas reservoir. Under such conditions, due to the hydrophilicity of the rock itself and capillary pressure, the intrusion of water does not effectively displace gas; instead, it traps the unexpelled gas within cracks, voids, or gaps, creating dead zones. The high-pressure gas trapped in this water invasion zone can account for 30% to 50% of the rock’s pore volume, thereby **reducing the ultimate recovery rate of the gas reservoir. Secondly, after water production from the gas well, the seepage resistance of the gas flowing to the bottom of the well increases, and the total energy consumption for the gas-liquid two-phase flow upward through the oil well increases significantly. As the impact of water invasion intensifies, the gas production rate of the gas reservoir decreases, the self-priming ability of the gas wells weakens, and the production per well declines rapidly until severe water accumulation at the bottom of the well leads to shutdown. Currently, managing water problems in gas reservoirs is mainly approached from two aspects: drainage and water plugging. Water plugging involves using methods such as mechanical blocking and chemical sealing to separate the gas-producing layer from the water-producing layer, or to create a water-blocking barrier within the reservoir. There are currently many methods for drainage, the main principle of which is to remove water accumulated in the wellbore; this is professionally referred to as drainage gas production method. Compressed natural gas pressure reduction stations: The small tubing drainage gas production method relies on the principle that, at a certain gas production rate, the smaller the diameter of the tubing, the higher the gas flow velocity and the greater its ability to carry liquid. If the tubing diameter is chosen appropriately, no water accumulation will occur at the bottom of the well. This method is suitable for wells in the early stage of water production, where formation pressure is high and water production is low. 　　The foam drainage gas production method involves injecting a foaming agent into the well through tubing or casings. The foaming agent mixes with the water present at the bottom of the well, forming bubbles; this not only reduces the specific density of the accumulated water but also allows the water produced from the formation to be carried to the surface along with the gas flow. This method is suitable for gas wells with high formation pressure and relatively low water production. 　　The plunger gas lift drainage gas production method involves inserting a plunger into the tubing. During descent, the flow channel in the plunger is open, and the plunger moves downward under the force of its own weight. When it reaches the bottom of the oil pipe, the flow channel in the plunger closes automatically. Since the pressure acting on the bottom of the plunger is greater than the pressure acting on its top, the plunger begins to move upward, pumping the water accumulated above it to the surface. When it reaches the top of the oil pipe, the flow channel in the plunger is automatically opened again, and it resumes moving downward. The accumulated fluid can be continuously drained through the reciprocating motion of the plunger. This method is suitable for gas wells with sufficient formation pressure and high water production. 　　The deep well pump drainage gas production method utilizes a deep well pump, sucker rods, and a surface pumping unit installed in the well to draw water through the oil pipes and produce gas through the casing, thereby controlling the pressure at the bottom of the well. This method is suitable for gas wells with low formation pressure, especially during the middle and later stages of production in water-producing gas wells, but the operating costs are relatively high. The main distribution areas of this section: Natural gas is a general term for mixed gases that exist in underground rock reservoirs and are primarily composed of hydrocarbons. This includes oil field gas, gas field gas, coalbed methane, mud volcano gas, and biogenic gas, among others. The main component is methane, usually accounting for 85-95% ； Next are ethane, propane, butane, etc. It is a high-quality fuel and chemical raw material. The associated gas is usually the volatile portion of crude oil, existing in gaseous form above the oil-bearing strata; it is present in all formations that contain crude oil, with only varying proportions of oil to gas. Even within the same oil field, the sources of oil and gas are not necessarily the same. They converge in the same rock reservoir through different pathways and via various processes. If it is non-associated gas, it is unrelated to liquid accumulation and may originate from plant matter. Of the world’s natural gas production, gas from gas fields and oil fields constitutes the main portion. The exploitation of coalbed methane is now receiving increasing attention. 　　China has a large area covered by sedimentary rocks and numerous continental basins, which create favorable geological conditions for the formation of various types of natural gas reservoirs. This is the geological backdrop for the distribution of natural gas resources in China. According to the 1993 estimates of China’s national natural gas resource potential, the total natural gas resources in China amount to 38 trillion m3. Onshore natural gas is primarily found in the central and western regions, accounting for 43.2% and 39.0% of the onshore resources respectively. The stratigraphic distribution of natural gas resources in China is mainly characterized by the Tertiary formations of the Cenozoic era and the Paleozoic formations; among the total resource volume, the Cenozoic accounts for 37.3%, the Mesozoic for 11.1%, the Upper Paleozoic for 25.5%, and the Lower Paleozoic for 26.1%. The origin types of natural gas resources are as follows: highly mature pyrolytic gas and coalbed methane play a dominant role, accounting for 28.3% and 20.6% of the total resources respectively; associated gas from oil fields makes up 18.8%, coalbed adsorbed gas accounts for 27.6%, and biogas constitutes 4.7%. China’s proven natural gas reserves are concentrated in 10 large basins, in the following order: Bohai Bay, Sichuan, Songliao, Junggar, Yinggehai-Qiongdongnan, Qaidam, Tuha, Tarim, Bohai, and Ordos. Chinese gas fields are mainly of small to medium size, and the geological structures of most of them are complex, making exploration and development challenging. Between 1991 and 1995, China’s natural gas production increased from 16.073 billion m3 to 17.947 billion m3, with an average annual growth rate of 2.33%. 　　The natural gas resources in our country are mainly distributed in the central and western basins. At the same time, our country also possesses unconventional coalbed methane resources that are primarily concentrated in the North China region. 　　After more than a decade of arduous exploration, the results are now clearly visible to the world. It shows that within our country’s 9.6 million square kilometers of land and over 3 million square kilometers of territorial waters, there are extremely abundant natural gas resources. 　　Experts predict that the total resource volume could reach 40–60 trillion cubic meters, making it a major country in terms of natural gas resources. The field of exploration is vast, holds tremendous potential, and has very bright prospects. 　　In recent years, there have been frequent positive developments in natural gas exploration across the east, west, south, north, and center of our motherland, which initially outline the trajectory for the development of natural gas in the 21st century. 　　East refers to the East China Sea Basin. There, the dawn of natural gas emission has already arrived ； 　　The south refers to the Yinggehai area, southeastern Hainan, and the Yunnan-Guizhou region. There, the grandeur of the atmospheric region has also been displayed ； 　　In the west are the Tarim Basin, Tuha Basin, Junggar Basin in Xinjiang, and the Qaidam Basin in Qinghai. At the western end of the ancient Silk Road, the drums of the battle for oil and natural gas are beating louder and louder. They will not only become important regions for the strategic succession of oil production in our country, but the flame of natural gas production there is also burning fiercely, with an unstoppable momentum ； 　　North refers to the vast regions of Northeast and North China. There are many large and established oil fields there, and with the advancement of future high technologies, they will not only be able to maintain stable oil and gas production but may also reach new heights ； 　　In China, they are the Ordos Basin and the Sichuan Basin. The scope of natural gas exploration in the Ordos Basin is expanding continuously, with proven reserves increasing sharply year by year, and development projects are underway. The Sichuan Basin is the main region for natural gas production in China, and recent new discoveries and significant breakthroughs mean that the development of natural gas will enter a completely new phase and reach a new level. 　　From north to south, from east to west, from land to sea, the flame of hope for natural gas burns brightly; the dream of becoming a major natural gas country will transform into a beautiful, colorful phoenix amidst that flame of hope. 　　With the advancement of technology, humanity will surely find an energy source that is more ideal than natural gas in the future world. But no matter what replaces natural gas in the future, it will continue to serve as an irreplaceable and important bridge toward new energy sources. Main categories of this section: Distribution of natural gas resources in China. In petroleum geology, this term usually refers to field gas and gas reservoir gas. Its composition is mainly hydrocarbons, with non-hydrocarbon gases also present. In a broad sense, natural gas refers to all gases that are naturally formed in the Earth’s crust, including oil field gas, gas field gas, mud volcano gas, coalbed methane, and biogenically produced gas. Based on the phase state of natural gas in underground, it can be divided into free state, dissolved state, adsorbed state, and solid hydrate. Only natural gas in a free state, which has aggregated to form natural gas reservoirs, can be developed and utilized. The main use of natural gas is as a fuel; it can also be used to produce carbon black, chemicals, and liquefied petroleum gas. Propane and butane, which are derived from natural gas, are important raw materials for modern industry. Natural gas is primarily composed of gaseous low-molecular-weight hydrocarbons and non-hydrocarbon gases. Liquefied Natural Gas (LNG) 　　　When natural gas is cooled to about -162°C at normal pressure, it changes from a gaseous state to a liquid state; this is what is known as liquefied natural gas (abbreviated as LNG in English). The main component of LNG is methane, with small amounts of ethane, propane, and nitrogen, among others. 　　Natural gas is further purified during the liquefaction process, resulting in a higher purity of methane; it contains almost no carbon dioxide or sulfides, and is colorless, odorless, and non-toxic. Liquefied Petroleum Gas (LPG) Liquefied petroleum gas is one of the petroleum products. Its English name is liquefied petroleum gas, abbreviated as LPG. It is a colorless, volatile gas obtained by pressurizing, cooling, and liquefying refinery gas or natural gas (including associated gas from oil fields). Liquefied petroleum gas obtained from refinery gas consists mainly of propane, propylene, butane, and butenes, with small amounts of pentane and pentenes as well as trace amounts of sulfur-containing impurities. The composition of liquefied gas obtained from natural gas basically contains no olefins. 　　Since natural gas is often found away from industrial or densely populated areas, issues related to transportation and storage must be addressed. The main component of natural gas is methane, whose critical temperature is 190.58 K; it cannot be liquefied by pressure alone at room temperature. Liquefaction and storage technologies for natural gas have gradually become major advanced technologies. 　　At present, liquefied natural gas (LNG) has become an emerging industry in our country, experiencing rapid development. In addition to being used to address transportation and storage issues, LNG technology is also widely employed as a peak-shaving device in natural gas utilization. Liquefied coalbed methane (HCL) 　　　China is a major coal-producing country, and it also possesses large reserves of coalbed methane, amounts that are roughly equivalent to those of natural gas. Its main component is methane. In addition to being a cheap chemical raw material, it is primarily used as fuel – not only as fuel for residents’ daily use but also as fuel for vehicles, ships, airplanes, and other modes of transportation. Due to its high calorific value and low environmental pollution from combustion products, coalbed methane is considered a high-quality, clean fuel. 　　There are several main advantages to using liquefied coalbed methane: ① Economic efficiency – lower investment costs and rapid recovery. 　　② Safety The approach of \"extracting gas first, then coal\" has become the basic method for energy utilization in developed countries. “\"Extracting gas first, then coal\" **increases the safety of coal mining. 　　③ Policy-related: This approach enables energy savings and ensures complete utilization of energy, in line with relevant ** policies. It helps to obtain ** support. 　　Coalbed methane liquefaction equipment is basically the same as natural gas liquefaction equipment; however, since the oxygen and nitrogen content in most coalbed methane is slightly higher than that in natural gas, an additional distillation system is required. The necessity of LNG production and use LNG has the following advantages over natural gas: ① It is easy to store and transport. The density of LNG is 625 times that of methane under standard conditions. In other words, 1 m3 of liquefied natural gas can be vaporized into 625 m3 of natural gas, which demonstrates the convenience of storage and transportation. 　　②Good safety performance. The current main methods for storing and transporting natural gas are compression (CNG). The high pressure of compressed natural gas poses many safety hazards. 　　③Low indirect investment. The volumetric energy density of compressed natural gas (CNG) is approximately 26% that of gasoline, while that of liquefied natural gas (LNG) is about 72% of gasoline’s – more than twice that of CNG. As a result, vehicles using LNG can travel greater distances, which in turn helps to **reduce the need for more gas stations. 　　④Peak-shaving function 　 As a fuel for household use or in power plants, natural gas inevitably experiences fluctuations in demand, which requires a peak-shaving function in terms of supply. 　　⑤Environmental friendliness: Natural gas must undergo strict pre-purification before being liquefied; as a result, the impurity content in LNG is much lower than that in CNG. This enables it to meet stricter emission standards when used in vehicle exhausts or as fuel (such as Euro II or even Euro III). 　　Natural Gas is a combustible gas formed over millions of years from ancient organisms buried underground under conditions of high temperature and pressure. It is a high-quality energy source that is colorless, odorless, non-toxic, has a high calorific value, burns steadily, and is clean and environmentally friendly. Natural gas is primarily composed of methane, with a calorific value of 8,500 kcal/m3; it is a gaseous fossil fuel that consists mainly of methane. It mainly exists in oil fields and gas fields, with a small amount also found in coal seams. 　　When non-fossil organic matter undergoes anaerobic decay, a methane-rich gas is produced, which is known as biogas (biomass gas). Sources of biogas include swamps between forests and grasslands, landfills, sludge in sewers, and manure, which is produced through the anaerobic decomposition by bacteria. Biogas also includes gastrointestinal gas (such as flatulence); this gas most commonly comes from livestock such as cows and sheep. 　　When methane escapes into the atmosphere, it becomes a greenhouse gas that directly contributes to the worsening of global warming. This dispersed methane is then considered a pollutant, rather than a useful source of energy. However, once methane in the atmosphere reacts with ozone through oxidation, it turns into carbon dioxide and water; therefore, the greenhouse effect caused by methane emissions is relatively short-lived. Moreover, in terms of combustion, natural gas produces much less carbon dioxide than coal and other Carboniferous-era fuels. Important biological sources of methane include termites, ruminants (such as cows and sheep), and human land cultivation. It is estimated that the emissions for these three are 15, 75, and 100 million tons per year respectively (with the total annual emissions amounting to about 100 million tons). 　　Pure natural gas contains: CH4 (98%), C3H8 (0.3%), C4Hm (0.3%), CmHn (0.4%), and N2 (1.3%). Its low calorific value is (36220 KJ/Nm3). Application areas: Due to its low cost, high calorific value, good safety properties, and environmental benefits, natural gas is the preferred fuel for domestic use. 　　Industrial fuel: Natural gas is used as a substitute for coal for heating factories, in boilers used in production processes, and in the boilers of gas turbines in thermal power plants. 　　Process production 　Such as paint baking production lines, tobacco leaf drying, asphalt heating and insulation, etc. 　　Chemical raw materials: Such as the use of methane from natural gas as a starting material for producing sodium cyanide, potassium xanthate, potassium hemate, and others. 　　Compressed natural gas vehicles are used to address the issue of vehicle exhaust pollution. Edit this section: Investment value. As a clean and efficient fossil fuel, natural gas is receiving increasing attention from countries around the world in terms of its development and utilization. Globally, the reserves of natural gas are much larger than those of oil, providing sufficient resource support for its development. It is expected that by 2030, natural gas will be on par with coal and oil in primary energy consumption. The peak period for natural gas lasts for a long time, and the emergence and rapid development of unconventional natural gas will surely sustain its fast growth, eventually surpassing oil to become the world’s most widely used energy source. Main advantages of this version: Natural gas is one of the safer gases; it contains no carbon monoxide and is lighter than air. In the event of a leak, it rises immediately, making it difficult for it to accumulate and form explosive mixtures, thus ensuring high safety levels. Using natural gas as an energy source can reduce the consumption of coal and oil, thereby **improving environmental pollution issues** ； As a clean energy source, natural gas can reduce sulfur dioxide and dust emissions by nearly 100%, cut carbon dioxide emissions by 60% and nitrogen oxide emissions by 50%. It also helps to reduce the formation of acid rain, alleviate the greenhouse effect on Earth, and fundamentally improve environmental quality. Its advantages include being environmentally friendly. Natural gas is a clean and high-quality energy source that contains almost no sulfur, dust, or other harmful substances. It produces less carbon dioxide when burned compared to other fossil fuels, resulting in a lower greenhouse effect; thus, it can effectively improve environmental quality. Cost-effective: Compared to city gas, natural gas has a similar calorific value per unit price. It is also cleaner, which helps extend the lifespan of cooking appliances and allows users to reduce maintenance costs. Natural gas is a clean fuel with stable supply, capable of improving air quality; thus, it can provide new impetus for the economic development of this region, driving economic prosperity and enhancing the environment. Safe and reliable Natural gas is non-toxic, easily dispersible, and less dense than air; it does not tend to accumulate in amounts that could cause explosions, making it a relatively safe fuel source. Improving living standards 　By using safe and reliable natural gas in households, the living environment can be greatly improved, thereby enhancing the quality of life. 　　Calculation of oxygen consumption for natural gas: When used for heating water in residential settings, 1 cubic meter of natural gas (with a purity of 100%) requires approximately 2.0 cubic meters of oxygen for complete combustion, and around 10 cubic meters of air is needed in total. Edit this section: Safety Management. Chapter 1: General Provisions. Article 1: These provisions are formulated in order to strengthen the safety management of urban gas and to protect human life and property. 　　Article 2: The urban gas referred to in these regulations means gaseous fuels such as natural gas, liquefied petroleum gas, and artificial gas (gas produced from coal or heavy oil), which are supplied for use in residential and industrial activities within cities. 　　Article 3: The production, storage, transmission and distribution, operation, and use of city gas, as well as the design and construction of gas projects and the production of gas appliances, shall all comply with these provisions. 　　Article 4 In accordance with the division of responsibilities stipulated by the State Council and the relevant laws and regulations, the Ministry of Construction is responsible for overseeing urban gas safety across the country; the Ministry of Labor is responsible for the safety inspection of urban gas nationwide; and the Ministry of Public Security is responsible for fire supervision related to urban gas throughout the country. The urban construction, labor (safety supervision), and public security (fire supervision) departments at the local people’s government level or above are responsible, in accordance with the division of responsibilities stipulated by the people’s government at the same level, for jointly overseeing the safety management of city gas within their respective administrative areas. 　　Article 5: The production, storage, transmission, distribution, operation, and use of urban gas must adhere to the principle of \"safety first, prevention foremost,\" with great emphasis placed on gas safety. 　　Article 6: Urban gas production, storage, transmission, distribution, and operation entities shall appoint a corporate officer in charge of gas safety matters, establish corresponding safety management institutions, and assign full-time safety management personnel ； Workshop teams should establish mass safety organizations and safety officers to form a three-level safety management network. Organizations using such systems should establish appropriate security management frameworks and assign specific personnel to be responsible for them. 　　Article 7: Urban gas production, storage, transmission, distribution, and operating entities shall strictly comply with relevant safety regulations and technical operating procedures, establish and improve corresponding safety management systems and rules, and enforce them rigorously. Chapter 2: Construction of Urban Gas Projects Article 8: The location selection for urban gas plants (stations), distribution facilities, etc., must comply with requirements related to urban planning and fire safety. During the site selection review, the opinions of the urban construction, labor, and public security fire departments should be sought. 　　Article 9: The design and construction of urban gas projects must be carried out by units holding the corresponding qualification certificates. 　　Article 10: The design and construction of urban gas projects must be carried out in accordance with the relevant safety standards, specifications, and regulations set by ** or the competent authorities. When reviewing gas engineering designs, representatives from urban construction, public security fire protection, and labor departments should be involved to ensure strict oversight of gas safety facilities. 　　Article 11: The construction of urban gas projects must ensure quality and be safe and reliable. At the time of completion inspection, relevant departments such as those in charge of urban construction, public security and fire protection, and labor, as well as experts in gas safety, should be invited to participate. Items that fail the inspection shall not be delivered for use. 　　Article 12: The commissioning of urban gas projects must be carried out with strict safety precautions, and it shall be done under the supervision and cooperation of gas production, storage, distribution, and operation entities as well as public security and fire departments. Chapter 3 Production, Storage, and Distribution of Urban Gas Article 13 The pressure and quality of urban gas supplied by production units must meet the standards specified in **; odorless gas must be odorized in accordance with relevant regulations. When producing gas using blast furnaces, water-gas furnaces, or oil-based gas generators, as well as when using electric tar collectors, their oxygen content must comply with the provisions of the \"Safety Regulations for Gas in Industrial Enterprises\". 　　Article 14: Quality analysis of the raw materials used for gas production and purification shall be conducted on a batch basis ； When necessary changes are made to the raw material varieties, analytical tests should be conducted. Raw materials that fail to meet the specified standards shall not be put into use. 　　Article 15: All types of boilers, pressure vessels, and gas cylinder equipment used in the production, storage, and distribution of city gas must comply with the safety management regulations issued by the labor department. They must be registered for use and subject to record-keeping as required, in addition to undergoing regular inspections ； Its safety accessories must be complete, reliable, and regularly calibrated. In cities where there are LPG filling stations, regular inspection stations for LPG cylinders must be established. Gas cylinder regular inspection stations and gas cylinder filling units should be planned, constructed, and put into operation simultaneously. Filling units that fail to carry out regular inspections of gas cylinders are not permitted to engage in gas cylinder filling operations. Cylinder inspection stations must be approved by the labor departments of the provinces, autonomous regions, and municipalities directly under the Central Government, and must obtain a qualification certificate before they can carry out cylinder inspection work. 　　Article 16: Before being put into operation, urban gas pipelines and containers must undergo a gas-tightness test and purging. During the replacement process, regular inspections should be carried out, along with enhanced monitoring and leak detection, to ensure safety and prevent leaks. All types of explosion-proof facilities and safety devices should be regularly inspected, and sufficient spare equipment, parts, as well as repair personnel and tools must be available to ensure their sensitivity and reliability. 　　Article 17: A hierarchical approval system shall be established for hot work in urban gas production, storage, and distribution systems. The entity carrying out the hot work must fill out an approval report and a work plan for such work, and submit them to the safety management department at the appropriate level; only after obtaining a hot work permit may the work proceed. When performing hot work, safety isolation and preventive measures must be taken around the work area. 　　Article 18: Urban gas production, storage, and distribution entities shall organize production, storage, and distribution in accordance with the load capacity of the equipment. In special cases where it is indeed necessary to increase production, scientific analysis and technical verification must be conducted, and the process parameters and production capacity of the equipment can only be adjusted after approval by the company’s chief engineer or the person in charge of technology. 　　Article 19: Urban gas production, storage, transmission, and distribution enterprises as well as the regulatory authorities must establish management systems for operations involving gas shutdowns and pressure reductions. These systems should include the authority for approving such operations, the procedures for submitting requests, and the measures to restore gas supply, with a technical department assigned to be responsible for these matters. For projects involving the suspension of gas supply or pressure reduction to users, it is not advisable to restore gas supply at night. Except in cases of emergency, gas outages and restorations of service should be notified to users in advance. 　　Article 20: No unit or individual is permitted to construct buildings, structures, or stack items on urban gas pipelines and facilities. When it is indeed necessary to construct buildings, structures, or store items near urban gas pipelines and facilities, it is mandatory to comply with the relevant provisions set out in the urban gas design codes and fire protection technical standards. 　　Article 21: Whenever construction is carried out near urban gas pipelines and facilities that may affect their safe operation, the construction party must notify in advance the entities responsible for the production, storage, transmission, and distribution of urban gas. Construction can only proceed after protective measures have been agreed upon by both parties. During construction, urban gas production, storage, and distribution operators shall provide on-site supervision as necessary. The construction party shall install clear signs at the construction site to strictly prohibit open flames, and protect the gas pipelines and facilities present there. 　　Article 22: Urban gas production, storage, and distribution enterprises shall conduct regular inspections of gas pipelines and facilities. Upon discovering any damage or leaks in such pipelines and facilities, they must repair or replace them promptly. 　　Chapter 4: Use of Urban Gas Article 23: Entities and individuals wishing to use urban gas must submit an application to the urban gas supply company; use is permitted only after approval is granted. Urban gas supply companies shall establish user records and sign supply and usage contract agreements with users. 　　Article 24: Units and individuals using city gas must obtain approval from the city gas operating company before installing additional gas supply and usage facilities. 　　Article 25: Urban gas supply companies must establish regulations for the safe use of gas by customers, provide safety education to residential users, carry out regular inspections of gas facilities, and offer services such as consultation ； Residential users must strictly abide by the safety usage regulations. Urban gas supply companies are responsible for conducting safety inspections and supervision of commercial customers, as well as providing technical training for their operators and maintenance staff. 　　Article 26: Units and individuals using gas pipeline facilities shall not dismantle, modify, relocate, or install gas facilities and appliances without authorization. It is strictly prohibited to install gas pipeline facilities and use gas in bedrooms, nor shall one draw gas illegally or use it by other improper means. 　　Article 27: Users shall not use any means to heat, drop, smash, or lay down liquefied petroleum gas cylinders; they shall not transfer the contents of the cylinders by themselves, drain residual liquid, or disassemble or repair accessories such as cylinder valves; nor shall they alter the inspection marks or the paint color of the cylinders. Chapter 5 Production and Sale of Urban Gas Appliances Article 28 When producing products subject to a production licensing system, manufacturers of urban gas appliances must obtain a \"Production License\" issued by the competent regulatory authority, and their products are subject to safety supervision by that issuing authority. 　　Article 29: The sale of civilian cooking appliances must be subject to testing at a testing center (station) designated by the urban construction administrative department of the city where they are sold. Only after passing such testing and meeting the requirements for gas use in that area, and under the safety supervision of a city gas operating unit designated by the same administrative department, can such appliances be sold. 　　Article 30: For gas appliances that have been approved for sale, the selling units shall establish maintenance stations at the place of sale; they may also entrust local urban gas supply companies to handle sales and repairs, and be responsible for providing the spare parts required for repairs. Urban gas supply companies shall assess professional maintenance personnel. 　　Article 31: Gas appliance products must be equipped with a product certificate and safety instructions for use, and obvious warning signs must be present on critical parts. Chapter 6: Emergency Repair and Handling of Urban Gas Accidents Article 32: An urban gas accident refers to an incident caused by gas that results in casualties and economic losses, such as poisoning, fires, or explosions. 　　Article 33: Upon discovering a gas accident, any organization or individual must immediately cut off the gas supply, take fire prevention measures such as ventilation, and report it to the entities responsible for the production, storage, distribution, and operation of city gas. Upon receiving a report, urban gas production, storage, transmission, and distribution entities shall immediately organize emergency repairs. In the event of a major accident, it is necessary to immediately report to the public security fire department, the labor department, as well as the units responsible for the production, storage, transportation, and distribution of city gas. The gas supply must be cut off right away, and the accident scene should be isolated and secured promptly. The scene must be protected so as not to hinder rescue efforts, order must be maintained there, and the progression of the accident must be controlled. 　　Article 34: Urban gas production, storage, transmission, distribution, and operation entities must establish dedicated emergency repair teams, equipped with sufficient repair personnel, protective gear, vehicles, equipment, communication devices, etc. They must also prepare emergency repair plans for various types of accidents, and promptly organize repairs once an accident occurs. 　　Article 35: The handling of urban gas accidents shall be carried out in accordance with the relevant regulations of the labor and public security departments, depending on the nature of such accidents. In the case of major and particularly serious urban gas accidents, follow-up actions should be carried out as swiftly as possible under the unified leadership of the urban residents. An accident investigation team composed of representatives from the urban construction, public security, and labor departments shall be formed to determine the causes of the accidents, take appropriate action in accordance with relevant laws, regulations, and rules, and submit reports thereon. Chapter 7 Rewards and Punishments Article 36 Units and individuals that have made significant contributions to ensuring the safety of urban gas should be commended and rewarded by the municipal administrative department in charge of urban construction, or by the entities responsible for the production, storage, distribution, and operation of urban gas. 　　Article 37: For those who damage, steal, or loot gas facilities but whose actions do not warrant criminal punishment, the public security organs shall impose penalties in accordance with the Law of the People’s Republic of China on Public Security Administration Punishments ； If a crime is committed, the judicial authorities will pursue their criminal liability in accordance with the law. 　　Article 38: In the case of violations of Article 20 of these regulations, urban gas production, storage, transmission, and distribution entities shall have the right to put such violations stop, order the removal of the illegal facilities within a specified time limit, and demand that the violators compensate for the resulting economic losses. 　　Article 39: In the case of violations of Articles 21, 24, 26, and 27 of these regulations, urban gas production, storage, distribution, and operation entities have the right to take action to stop such violations and order that things be restored to their original state. For those who continue to violate these rules despite warnings or whose actions pose a risk to the safety of gas use, such entities may, with the approval of the municipal people’s government’s administrative department in charge of urban construction, take measures to suspend gas supply in order to ensure safety. 　　Article 40: If a party is dissatisfied with a penalty decision, it may, in accordance with the relevant provisions of the Administrative Litigation Law of the People’s Republic of China, apply for reconsideration or file a lawsuit with the people’s court. If an application for reconsideration is not filed within the prescribed time, or no lawsuit is filed with the people’s court, and the penalty decision is not complied with, the administrative agency that issued the penalty decision may apply to the people’s court for compulsory enforcement, or enforce it in accordance with the law. Chapter VIII Supplementary Provisions Article 41 The people’s **construction administrative departments of various provinces, autonomous regions, and municipalities directly under the Central Government may, in conjunction with the labor and public security departments, formulate detailed implementation rules in accordance with these provisions, which shall be submitted to the people’s **at the corresponding level for approval and implementation. 　　Article 42 These provisions shall be interpreted by the Ministry of Construction. 　　Article 43 These provisions shall come into force as of May 1, 1991. Any previously issued regulations that conflict with these provisions shall be governed by these provisions. Edit this section: Domestic gas. The combustion gases used in people’s daily lives can be roughly divided into three categories: liquefied petroleum gas (Y), artificial gas (R), and natural gas (T). 　　Liquefied petroleum gas (abbreviated as LPG) is a by-product of petroleum that remains after the extraction of gasoline, kerosene, diesel, heavy oil, and other petroleum products. Through specific processes, this petroleum by-product is recovered and utilized; by applying pressure, it is turned into a liquid state and stored in pressurized containers, which is how LPG got its name. Its main components include ethylene, ethane, propylene, propane, and butane, etc. It is in a liquid state inside gas cylinders; once it escapes, it vaporizes into a flammable gas whose volume is about 250 times larger than the original volume, and it spreads very easily. It will catch fire or explode when exposed to an open flame. Therefore, special care must also be taken when using liquefied gas. 　　Gas is produced by dry distillation or vaporization of solid raw materials such as coal or coke, and its main components include carbon monoxide, methane, hydrogen, etc. Therefore, gas is toxic and can easily form explosive mixtures with air, so extreme caution must be exercised when using it. 　　Natural gas, in a broad sense, refers to the collective term for gases that are naturally formed and buried in geological strata. However, the natural gas commonly referred to refers only to a hydrocarbon-rich combustible gas stored in deeper layers of the earth, while natural gas that coexists with oil is often called associated gas from oil fields. Natural gas is formed from organic matter that dates back millions of years; its main component is methane. Depending on the geological conditions under which it was formed, it also contains varying amounts of lower hydrocarbons such as ethane, propane, butane, pentane, and hexane, as well as non-hydrocarbon substances like carbon dioxide, nitrogen, hydrogen, and sulfides ； Some gas fields also contain helium. Natural gas is an important energy source, widely used as city gas and industrial fuel ； In the 1970s, natural gas accounted for about 18%–19% of the world’s energy consumption. Natural gas is also an important chemical raw material. 　　The calorific value of natural gas per cubic meter ranges from 8,000 to 8,500 kcal. 　　The calorific value of liquefied gas per kilogram is 11,000 kcal. The specific gravity of gaseous liquefied gas is 2.5 kilograms per cubic meter. The heat value of each cubic meter of liquefied gas is 25,200 calories. It can be seen that the calorific value of one cubic meter of liquefied gas is three times that of natural gas, but there are also reports stating that its calorific value is 7 times that of natural gas. 　　Each bottle of liquefied gas weighs 14.5 kilograms, with a total heat of combustion of 159,500 kcal, which is equivalent to the heat of combustion of 20 cubic meters of natural gas.

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