【In-depth Discussion on Modular Installation of Haichuan】Module installation at Moyi Natural Gas Purification Plant designed using 3D models

On December 1, production data from the Southwest Oil and Gas Field showed that since the commissioning of Well Moxi 8 at the end of 2013, the gas reservoir in the Longwangmiao Formation at Moxi has produced nearly 9 billion cubic meters of gas over those 3 years. The Longwangmiao Formation gas reservoir in the Moxi block of the Anyue gas field is the largest single marine coherent gas reservoir discovered in China to date. Here, the Southwest Oil and Gas Field, together with the participating contractors, pioneered the use of modular unitization in large-scale natural gas processing plants in China, contributing to the achievement of a production capacity of 10 billion cubic meters of natural gas per year for this gas reservoir within 3 years. “What is the secret to “fast and efficient production”? Two main battlefields separated by 40 kilometers – On October 15th, in Dingjiaping Village, Moxi Town, Suining City, at Moxi Purification Plant No. 2, inside the seven-story-high purification unit modules, sparks were flying as welders, plumbers, and electricians worked in different areas. On the ground access roads, cranes, excavators, and construction vehicles move back and forth. Safety supervisors and quality inspection personnel are on high alert, keeping a close eye on all areas involving risky operations. The reporter put on protective gear and walked carefully around the construction site. There is some mud in front of the equipment area, which is different from what we experienced at the skid plant earlier. On July 9, a rainy day, in Chuanshan District of Suining, the reporter drove 40 kilometers to the mobile production plant of Sichuan Qingdao Drilling Oil Construction Company to conduct an interview. This factory was established as part of the Moxi Purification Plant No. 2, and it was created by converting the material storage area at the Suining warehouse of the Southwest Oil and Gas Field Materials Company into a manufacturing facility. The factory building is spacious and well-lit, with different work areas designated according to the workflow. After welding a section of special steel, Liu Changsheng took off his goggles and told the reporter, “In the past, when working outdoors, I would be sweating on sunny days and covered in mud on rainy days.” Today, with factory-based prefabrication, tools are arranged in an orderly manner, resulting in a better working environment and higher efficiency. ” In March this year, after the various types of equipment purchased through a unified tender by the Southwest Oil and Gas Field arrived, the workers at the skid-mounted plant pre-assembled the modules in the factory building according to the blueprints. In mid-July, after undergoing purging, pressure testing, and passing inspection, these skid-mounted units were disassembled according to the transport capacity of the vehicles and transported sequentially to the site of Moxi Purification Plant No. 2. The workers then quickly assemble it on-site, just like building with blocks, following the reassembly manual. “The two main battlefronts fought side by side. ”Ma Zhengfu, the deputy director of the skid-mounted plant, explained that the second phase of the Moxi Purification Plant 2 project includes 222 large skid-mounted modules and 24 large tower-type devices. Throughout the entire project construction period, within the skid factory, the skid assembly work was carried out in an intense and orderly manner ； At the construction site, civil engineering work, high-risk lifting operations of tower equipment, and the reassembly of skid blocks are carried out in sequence. Compared to the traditional method of on-site material cutting and piping installation, the process has been optimized, safety has been ensured, and the construction time has been reduced by 30% to 50%. In the automated welding workshop, machines emit soft humming sounds and sparks fly as 10 automatic cantilever welding machines are arranged in a line, with red robotic arms carrying out precise welding on the pipe joints. Ma Zhengfu explained that the factory carries out centralized heat treatment in batches for the pipes that have been welded and prefabricated, which avoids the defects and potential risks associated with heat treatment at individual weld sites. As a result, the first-pass qualification rate for welds increased by 3.5%. \"Prefabrication in a factory setting helps to shorten the construction time while ensuring better quality; it’s like having the best of both worlds.\" ”

In September 2012, the major discovery at Well 8 in Moxi unveiled the mysteries of the gas reservoir in the Longwangmiao Formation. One month later, with the aim of developing the gas reservoir in the Longwangmiao Formation as quickly as possible to meet society’s demand for clean energy, the idea of building a new purification facility with an annual production capacity of 1 billion cubic meters at the Moxi purification plant was conceived: the old plant’s sulfur processing and boiler workshops would be demolished, and a larger-scale purification facility would be constructed on their site; both the old and new plants would share common facilities in order to achieve rapid production. Building a factory within another factory means carrying out construction while production is in progress in a large-scale chemical plant – how can safety risks be mitigated? The space is limited; how should the purification devices be placed? With a tight deadline, how can we accelerate progress scientifically? The approach of factory-based prefabrication and modular skid assembly is extended from well stations to the plant area, marking the first instance of skid-mounted construction for large-scale purification plants in China. Land is limited; \"trade height for space.\" The purification devices that were previously installed on the ground now \"live\" on three- to four-story-high steel structure platforms. Factory prefabrication means \"trade space for time\" – fighting on two fronts at the same time, thus ensuring quality, schedule, and safety. In project construction, international first-class 3D modeling technology is employed for module design, factory prefabrication, and on-site construction. Creating 3D models of modular factories facilitates collaborative work among designers on the same platform ； During factory-based prefabrication, secondary design is carried out using 3D models to determine the methods for splitting and combining prefabricated components and pipes; production is scheduled in an orderly manner, material mixing is automated, thereby enabling visual and digital management. The Southwest Oil and Gas Field has established a dedicated project management team to implement a \"one-stop service\" approach, uniting the efforts of various parties involved in design, procurement, construction, supervision, and testing in order to strive for the \"**Quality Project Gold Award**.\" The second phase of the Moxi Purification Plant 2 project, which began construction at the end of 2014, is located next to the existing purification facility with a daily capacity of 12 million cubic meters; it involves the construction of three new facilities, each with a daily capacity of 6 million cubic meters. With high safety pressures and limited construction space, modular skids once again play a key role in enabling \"construction within a factory\". On October 20, the production capacity project for the Moxi Longwang Temple gas reservoir, with an annual output of 6 billion cubic meters of gas, was officially put into operation. To date, 9 sets of \"integrated units for desulfurization, dewatering, and sulfur recovery\" as well as nearly 30 sets of integrated gas collection units per well have been successfully installed in this gas reservoir. Following the approach of \"overall planning and phased implementation,\" the Southwest Oil and Gas Field has vigorously promoted integrated exploration and development, setting new records for increasing production from large-scale gas reservoirs in China’s petroleum industry: it took 10 months to establish a production facility with an annual output of 1 billion cubic meters, 15 months to achieve an annual output of 4 billion cubic meters, and 13 months to reach an annual output of 6 billion cubic meters. To date, the pilot production project aiming for an annual output of 1 billion cubic meters and the project aiming for an annual output of 4 billion cubic meters in the Longwangmiao Formation gas reservoir have been operating stably, at full capacity, and with excellent performance for two years and one year respectively. The quality and effectiveness of the modular factory construction model have withstood the test of actual production.

Related reading: What is the modular skid-mounted system? Against the backdrop of the group company’s strong push for standardization, the Southwest Oil and Gas Field has adopted a new model for capacity construction in the construction of purification plants and well stations, which combines standardized design, factory prefabrication, and modular assembly. This approach involves dividing the various production units of large-scale oil and gas facilities into multiple modules that fit within transport dimensions. The modules are manufactured and pre-assembled in the prefabrication plant; once they pass the inspection, they are disassembled and transported to the construction site, where they are then reassembled and connected in a \"building blocks\" manner. Skid-mounted: a set of equipment fixed on the same chassis, named so because it can be moved using a lever. Modular skid-mounted, requiring a crane or hoist for movement. An eyewitness says: What should be considered when building a factory in a modular manner? (Ning Yongqiao, Deputy Chief Engineer of the construction project team for the gas reservoir in the Moxi Longwangmiao Formation, with an annual production capacity of 6 billion cubic meters) The modular plant construction approach has played a significant role in achieving high quality, efficiency, as well as rapid construction and operation for the gas reservoir in the Moxi Longwangmiao Formation of the Anyue gas field. It has led to the development of a new modular design pattern for large-scale natural gas processing plants in China, offering practical insights that can be applied and replicated elsewhere. The advantages of the modular factory construction approach are mainly reflected in five aspects: the layout of the facilities shifts from a flat arrangement to a stacked configuration, thereby saving land use ； The assembly of skids and on-site civil construction were carried out simultaneously, reducing the project duration ； Factory prefabrication makes extensive use of automated equipment, improving construction quality ； Reduced concurrent operations on site, lowering safety risks ； The prefabrication plant is not affected by heat or rain in terms of its production schedule, and the working conditions for employees have improved. However, the modular factory construction model also has some problems and shortcomings: Modular factory construction requires certain prerequisites. For the second phase of Moxi Purification Plant 2, each sulfur recovery unit has a production capacity of 9 million cubic meters per day. The equipment and pipelines are of large size; the maximum dimensions of the skid-mounted steel structures exceed the limits for transportation, making it impossible to assemble them in modular skids. Therefore, in-depth factory-based prefabrication is required. Based on current experience with modular units, it is recommended that for natural gas purification plants with a processing capacity of over 6 million cubic meters per unit, the components be prefabricated in a factory and then transported to the site for direct installation. One of the advantages of modular plant construction is the ability to advance civil work and process installation simultaneously. If factory prefabrication begins only after the civil engineering is completed, the advantage of saving time is not evident. Therefore, by stockpiling some process materials and carrying out prefabrication in a factory setting in advance, the advantages of modular construction can be maximized. From the perspective of project investment control, due to the need for transporting large modular skids, or building prefabrication plants in nearby locations, as well as the extensive use of steel structures for skid bases, the project investment does not have significant advantages over conventional plant construction. However, the overall benefits of project construction resulting from improved project quality, reduced construction safety risks, and shortened construction timelines far exceed the modest increase in project investment. From the perspective of modular design, due to transportation constraints and space limitations within the modules, the installation of equipment and processes is rather compact; as a result, some equipment may present difficulties in maintenance and replacement later on. This requires selecting and purchasing equipment and valves of reliable quality to reduce the frequency of repairs. From a construction perspective, the procurement costs are higher, but over the entire life cycle of the project, the costs are reduced and production becomes safer. The integrated skid unit for gas production stations has a relatively simple function; its total weight is low, making it easy to manufacture in factories, transport, and install on-site. It is particularly suitable for rapid construction and operation to increase production capacity, offering significant advantages in terms of cost savings and land use efficiency.

On March 4, the first exhaust stack tower for the Moxi No. 2 purification plant of the Longwangmiao gas reservoir was successfully lifted into place; it is 112.5 meters in height and weighs approximately 203 tons. The Moxi No. 2 Purification Plant for the gas reservoir in the Longwangmiao Formation is designed to have two identical exhaust chimney towers; the one being lifted this time is the first such tower. The lifting operation was carried out using two 500-ton crawler cranes as the main lifting equipment, along with a 260-ton crawler crane to assist in the lifting process. The success of this lifting operation marks a new phase in the construction project of the Moxi No. 2 purification plant for the Longwangmiao gas reservoir.

NW software is quite good at doing this

Reading from beginning to end, it can be said that what my colleagues and I in the southwest region worked on abroad were modular natural gas processing plants; this gas field back home represents their finest achievement, though they have since undertaken fewer modular projects.

After all, there are only a few purification plants; it seems there are some in Xinjiang as well