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Where to Find Oil and Gas in the Vast Oceans (Part 1) http://www.oilnews.com.cn/bk/images/070821/A012007011.jpg China Petroleum News Center http://www.oilnews.com.cn/bk/images/070821/A012007011.jpg Offshore oil and gas exploration involves the process of searching for oil and gas fields in the vast oceans. By utilizing various advanced exploration techniques and methods, based on the principles of oil and gas distribution as outlined in petroleum geology, it is possible to identify oil and gas reserves in the most cost-effective manner. In the vast ocean, oil and gas fields account for an extremely small fraction. If one relies solely on drilling to locate such fields at a specific location, it is truly like looking for a needle in a haystack. One can’t help but wonder where to find oil and gas in the vast ocean Oil and gas exploration involves studying geological history and geological patterns in order to locate oil and gas fields following scientific procedures. It mainly involves four steps: first, determining the extent of ancient lakes and oceans; second, identifying the deep depressions where oil could have been formed; third, searching for geological traps around these oil-forming depressions that are conducive to the accumulation of oil and gas; and finally, drilling in the most promising traps to verify whether oil or gas is present and to determine its reserves. Oil was formed in the sediments of ancient lakes or oceans, and oil and gas fields also developed there. Therefore, determining the location and extent of ancient lakes and seas is of primary importance. The basis for determining the location of ancient lakes and seas is mainly the study of rocks and fossils. Sedimentary rocks are the primary material basis for determining ancient lakes and seas. In other words, wherever there are sedimentary rocks, there were ancient lakes or oceans. What is the difference between ancient lakes and ancient oceans? This is mainly determined and distinguished through fossils, as the biological characteristics of lakes and oceans differ significantly. Furthermore, even among the same sedimentary rocks, the physicochemical properties of lake and marine rocks differ. Simply put, it is classified based on the salinity of the water at that time; generally, fresh water corresponds to lakes, while salt water corresponds to seas. The preservation status of ancient lakes and seas is of great importance for oil and gas exploration. Over subsequent geological changes, they may have suffered from weathering and erosion, resulting in incomplete structures, or they may have been damaged by the intrusion of igneous rocks, or undergone severe metamorphic processes, among other things. The development process of these conditions also needs to be determined by examining aspects such as the properties of the rocks and the degree of preservation of the strata. Whether it is a lake basin or an ocean basin, their area is very large, usually exceeding tens of thousands of square kilometers. The shape of the pelvic floor is also uneven and irregular, with variations in height and depth. The lower parts are referred to as depressions, while the higher areas are called elevations or protrusions. Generally, the remains of aquatic organisms tend to accumulate at the bottom of the basin floor; therefore, depressions are considered to be areas in the basin floor that are conducive to oil formation. Of course, the deeper these depressions are, the better. Thus, after determining the boundaries of the basin floor, the next step is to identify the locations of the deepest depressions – those places where the most oil and gas can be formed. Finding geological traps is the key step in searching for oil fields. Any oil and gas sector that undertakes this work attaches great importance to it. Geological traps vary in size and depth, and come in various shapes. Finding traps also involves a process that progresses from shallow to deep, and from large to small. It is of course very difficult to locate deep and small traps, as it requires a much higher level of technical precision and complexity than in ordinary cases. After identifying a geological trap, it is also necessary to conduct research and evaluation to determine whether the trap possesses the conditions for oil storage. Generally speaking, geological traps located near oil-generating depressions are conducive to the migration of oil and gas, making them promising oil and gas fields, whereas traps in other locations are assessed as being of lower quality. Furthermore, it is also necessary to study and evaluate factors such as the integrity of preservation of each trap itself and the amount of oil and gas it can store. Where to find oil and gas in the vast oceans (Part 2) http://www.oilnews.com.cn/bk/images/070821/A012007011.jpg China Petroleum News Center http://www.oilnews.com.cn/bk/images/070821/A012007011.jpg It is generally difficult to determine whether oil and gas are stored within a geological structure that has been identified, until drilling operations are carried out to verify this. Therefore, drilling geological traps is the final step in searching for oil and gas fields, and it is an extremely important and crucial step. Its importance and significance lie in the fact that all the techniques and methods employed in this step are related to whether an oil field can be successfully developed and what its ultimate fate will be. Determining the location where the first exploration well or wells should be drilled within a basin or an enclosure requires taking various types of data into consideration. In simple terms, exploration wells drilled to find oil and gas are always located as high as possible within the trap, as oil and gas always float on top of water. The so-called “height” here refers to the height of the oil-bearing layer. The geological structure is very complex, as \"high\" is not an absolute term. To put it vividly: if the reservoir to be drilled resembles an upside-down bowl or basin, the first drilling well is located at the bottom of that arched bowl or basin ； If this trap resembles a large fish lying vertically, the location of the first well should be determined at the high point of its back ； If the trap resembles an inclined plate, the exploration well is located above it. There are also very few exceptions; for example, ordinary people have the thickest hair on the top of their heads, while those who are bald have hair only around the perimeter of their head. Trying to cut hair in the area on top of the head is pointless. There are indeed cases where oil has been found in the \"pelvic floor\" area; it’s like adding some oil to a wok used for cooking – the oil can’t stay at the rim of the wok. This is because there is almost no water in the strata here, so the oil cannot float and has to \"sink to the bottom.\" Such examples are rare, which is why \"searching for oil in higher areas\" remains the principle that should be followed first. When a geological trap is drilled and a well produces oil or gas of commercial value, an oil or gas field has been discovered. However, it is still necessary to further clarify the specific boundaries of this oil and gas field as well as its oil production capacity. Therefore, once oil and gas are detected during drilling, it is necessary to immediately determine the number of layers, thickness, and depth of the oil and gas reservoirs. The lithology and other physical properties of these reservoirs also need to be ascertained, in addition to testing the reservoir’s oil production capacity and analyzing the properties of the crude oil. Then, expanded drilling is carried out to further determine the oil and gas presence within the trap, and to calculate the amount of oil and gas reserves underground. In this way, for a single oil and gas field, its preliminary exploration work is considered complete. In the actual work of searching for oil and gas fields, these steps cannot be carried out separately; rather, they are always interrelated and take place simultaneously. In the process of searching for structures favorable to oil generation, geological traps are often found simultaneously ； During the search for geological traps, new sedimentary formations or new oil-generating basins can also be discovered ； When drilling for traps, new oil-generating layers and reservoirs are also discovered, providing people with many new insights. In general, the process of searching for oil and gas fields is, on the one hand, a process of continuously gathering data on underground conditions to deepen understanding, and on the other hand, a process of continuous advancement in oil and gas exploration technologies. As an important unit within China National Petroleum Corporation for accelerating the exploration and development of offshore oil and gas resources, China National Offshore Oil Engineering Co., Ltd. currently possesses 8 various types of mobile platforms, 1 modular drilling rig, and 17 ships. It has the capability to provide comprehensive integrated services for offshore oil and gas exploration and development projects, and serves as a key force in China National Petroleum Corporation’s offshore oil and gas development efforts. (Cui Mo, excerpted from ‘Shallow Sea Oil and Gas Exploration and Development’) This post was last edited by Wutongshu on 2009-3-4 at 17:24.]