Abstract: This paper reviews the development history of energy-saving technologies in oil and gas fields by China National Petroleum Corporation (CNPC), summarizing the progress and development in energy-saving technologies in areas such as surface engineering optimization and simplification, pumping unit systems, vented natural gas recovery, ambient temperature crude oil gathering and transportation, heavy oil thermal recovery, and high-efficiency energy-saving equipment for oil and gas fields. It proposes that, given the current national emphasis on energy conservation and the increasing difficulty of oil and gas field development, developing energy-saving technologies is an important way for oil and gas field enterprises to transform their growth model. Based on the development trends of energy-saving technologies in oil and gas fields both domestically and internationally, this paper forecasts the future energy-saving technology needs of major oil and gas field production systems, proposing technological development directions such as overall optimization of aboveground and underground systems, utilization of waste heat from produced water, unheated oil gathering, heavy oil thermal recovery, and utilization of new and renewable energy sources. Keywords: Oil and gas field energy-saving technology development prospects Introduction China National Petroleum Corporation (CNPC) has developed into a comprehensive energy company integrating oil and gas exploration and development, refining and chemical engineering, oil product sales, oil and gas storage and transportation, petroleum trading, engineering and technical services, and petroleum equipment manufacturing. The company is both a major energy producer and consumer, with its annual comprehensive energy consumption accounting for approximately 2%-3% of the national total in recent years. Oil and gas field production is one of the company's main business segments, consuming about half of the company's total energy. Energy conservation and consumption reduction are crucial for China National Petroleum Corporation (CNPC) to change its economic growth model and build a resource-saving enterprise. According to research, there are three ways to conserve energy: structural energy conservation, technological energy conservation, and management energy conservation. Currently, the contribution rate of technological energy conservation in China is only 13.4%. This means that the current pace of technological progress cannot meet the requirements for achieving the "Eleventh Five-Year Plan" energy conservation targets. There is a lot of room for developing energy-saving technologies, and it is necessary to accelerate the pace of technological progress. Summarizing and reviewing the development of energy-saving technologies in oil and gas fields and looking ahead to future technological needs is of great significance for improving the energy efficiency of oil and gas field production. I. Review of the Development of Energy-Saving Technologies in CNPC Oil and Gas Fields (I) Review of the Promotion of Energy-Saving Technologies CNPC attaches great importance to the development of energy-saving technologies in oil and gas field operations. Through multi-level promotion, including research on key energy-saving technologies, construction of energy-saving demonstration projects, energy-saving technology exchanges, and special investments in energy conservation, it continuously improves the level of energy-saving technologies in oil and gas fields and taps the potential for energy conservation. 1. Conducting research on energy-saving potential and promoting the construction of energy-saving demonstration projects: Active research was conducted on the current status of energy consumption in oil and gas fields, analysis of energy-saving potential, and development strategies for energy-saving technologies, thus promoting the development of energy-saving technologies. For example, the project "Investigation and Research on the Technical and Economic Level of Petroleum and Petrochemical Construction Engineering," completed in 1999, conducted a comprehensive survey of the construction and operation of oil and gas field projects at home and abroad, as well as technological development trends. It compared domestic and international technical and economic levels, summarized and analyzed existing gaps, and proposed measures and suggestions for development goals. The projects "Research on Energy-Saving Potential of Oil and Gas Fields" and "Application Research on Energy-Saving Demonstration Projects in Oil and Gas Fields," conducted from 2002 to 2004, surveyed the energy consumption and energy-saving technologies of the "five major systems" of oil and gas fields in 10 oil and gas fields, including Daqing, Liaohe, and Xinjiang. The projects organized various oil fields to select and compile energy-saving demonstration project plans, ultimately determining and implementing two energy-saving demonstration projects: the Daqing high-water-cut project and the Xinjiang heavy oil thermal recovery project. This greatly promoted the development of advanced and typical energy-saving technologies. 2. Organizing Energy-Saving Technology Exchanges and Promoting the Dissemination and Application of Energy-Saving Technologies: Since 2001, the company has held numerous large-scale energy-saving and water-saving technology exchange conferences in various formats throughout the company. Through these conferences, the publication of exchange materials and technical guides on energy-saving and water-saving technologies, the company has promoted the application of advanced and applicable energy-saving and water-saving technologies. From 2001 to 2006, the company successively held four thematic exchange conferences on energy-saving technologies for oil and gas fields. In 2004, China Petroleum Exploration and Production Branch held on-site meetings on "Optimization" and "Simplification," respectively. Various oil and gas field enterprises also actively carried out energy-saving technology exchanges and training, achieving good results. Energy-saving technologies such as vacuum heating furnaces, ambient temperature gathering and transportation, optimization of pumping wells, and comprehensive utilization of vented natural gas recovery have been promoted and applied. Energy-saving technology exchange conferences have become an effective platform for experience exchange, technology exchange, and information exchange. 3. Establish special investment for energy conservation and accelerate the development of key energy-saving technologies. Adhering to the principles of "highlighting key areas, prioritizing benefits, demonstrating typical examples, and implementing mature technologies first," and in conjunction with the secondary development of old oilfields, priority is given to key projects that are technologically mature, have significant effects, and serve as typical demonstrations. A number of energy-saving technology transformation projects are implemented, focusing on energy conservation in mechanical extraction, water injection, power systems, and gas and oil conservation in gathering and transmission systems. Efforts to recover and utilize associated gas are also intensified. Since 2004, the "Double Ten" project for optimization and simplification has been organized and implemented, with special projects for optimization and simplification of the "Double Ten" project arranged for three consecutive years. During the "Eleventh Five-Year Plan" period, a special plan for energy conservation in oil and gas fields was formulated, with a planned investment of 4.8 billion yuan in energy conservation projects in oil and gas field operations. Currently, 2.4 billion yuan of investment has been allocated. These efforts have effectively promoted the development of energy-saving technologies and improved system operating efficiency. 4. Establish a technology promotion catalog to guide the promotion of mature energy-saving technologies. For energy-saving and water-saving technologies with existing successful application cases, mature technology, strong applicability, and significant effects, China National Petroleum Corporation plans to establish a promotion catalog in batches and organize the promotion and application in conjunction with equipment upgrading and elimination. In 2008, a total of 36 energy-saving and water-saving technologies were included in the first batch of promotion catalogs, while 32 types of inefficient and high-consumption equipment in 17 categories were included in the first batch of elimination catalogs. (II) Achievements in the Development of Energy-Saving Technologies Since the early 1980s when the state began to carry out energy-saving work in a planned manner, and since the state has strengthened energy-saving work in the 21st century, energy-saving work and technologies in oil and gas production have been continuously developing and improving. From the initial foundation-laying and plugging leaks; to carrying out energy-saving technology transformation of unit equipment and single processes; to carrying out system optimization and improving system operating efficiency; and further focusing on the perfect matching of energy-saving technologies between various energy-consuming systems and between them, and implementing energy cascade utilization according to grade. Energy-saving technologies in oil and gas fields have been developing in a more in-depth, detailed and efficient direction, and have achieved great breakthroughs. The following is a summary of energy-saving technologies that have made significant breakthroughs in recent years. 1. System Optimization Optimizing the surface engineering system of oil and gas fields is an important aspect of improving the efficiency of oil and gas field systems. To adapt to the changing landscape of old oil and gas field development, China National Petroleum Corporation (CNPC) management, from the perspective of upstream business development strategy, proposed to "focus on both optimizing new oilfields and simplifying old oilfields," and organized the implementation of the "Double Ten" optimization and simplification project. This involved intensifying adjustments and upgrades, primarily through "shutting down, merging, converting, and reducing" operations, along with supporting energy-saving technological transformations, gradually forming a set of effective adjustment and upgrade models and technical measures. From 2004 to 2006, a total of 60 key optimization and simplification projects were implemented. After implementation, these projects met the requirements for surface construction: "advanced and applicable technology, streamlined and simplified processes, reasonable investment, and compliance with safety and environmental standards." Surface process flows were further simplified, with single-pipe processes increasing by 28%; investment and operating costs were effectively controlled, saving 2.3 billion yuan in construction investment and 890 million yuan in annual operating costs; energy consumption was reduced, with comprehensive energy consumption per ton of oil decreasing by 7%. Liaohe Oilfield has implemented simplification measures such as "closing, stopping, merging, converting, and reducing" in recent years. These measures have resulted in the closure of 76 joint stations, oil production stations, water injection stations, and light hydrocarbon stations; the shutdown of 998 pieces of production equipment and 2 sets of facilities; the merging of 151 pieces of equipment and 31 pipelines; the conversion of 54 metering transfer stations to metering stations; the conversion of 444 single-well oil extraction to transfer; the reduction of the capacity of 412 transformers; and the downgrading of 54 pumps. Ninety-seven technological upgrades and process energy conservation measures have been implemented, resulting in cost reductions and efficiency improvements of 300 million yuan. Following the overall transformation of Jilin Fuyu Oilfield, three centralized crude oil processing stations were reduced to one; the number of transfer stations decreased from 25 to 6; the number of crude oil export outlets decreased from three to one; the original 321 metering stations were converted to 199 valve stations; and the 23 gathering and transmission trunk lines were optimized to 12. By simplifying and optimizing the surface gathering and transportation process and increasing the application of energy-saving equipment, the operating efficiency of the surface system has been effectively improved, and oil and gas gathering and transportation losses have been reduced. This has resulted in annual savings of 17,000 tons of crude oil for self-use and 20 million kilowatt-hours of electricity, forming the "Fuyu Oilfield Model" with typical demonstration significance. The Changqing Xifeng Oilfield officially commenced development in 2003. In accordance with the requirements of building a "New Century Demonstration Oilfield," the initial construction phase focused on reducing construction investment and improving development efficiency. Guided by the principles of innovation, optimization, and the application of advanced and applicable technologies, through continuous innovation, practice, and exploration, it successfully applied multiple technologies, including wellhead dynamometer card metering, closed-loop oil and gas gathering and transportation, three-phase separation of crude oil, comprehensive gas utilization, water distribution using flow stabilizing valve groups, and well station automation. This has formed the "Xifeng Model" technology, characteristic of the Changqing low-permeability oilfield. Through continuous optimization, the Xifeng Oilfield surface system has seen continuous improvement in its surface construction level and technological innovation, reducing the comprehensive energy consumption per ton of oil from 125 kg/ton of standard coal to 90.3 kg/ton of standard coal. 2. Pumping Units and Supporting Energy-Saving Technologies: Mechanical oil recovery is the primary method of oil production in oilfields, with mechanically operated wells accounting for over 98% of all oil wells. Through long-term development, pumping unit systems, from the surface to the wellbore, have formed a complete set of energy-saving technologies, such as dedicated energy-saving motors for pumping units, energy-efficient pumping units, narrow V-belt couplings, self-aligning graphite packing boxes, and sucker rod string centralizers. These technologies are optimized to achieve the best energy-saving effect. In terms of system design, North China Oilfield has independently developed pumping unit optimization design software. This software treats the pumping unit system as a whole, optimizing the combination of stroke, stroke frequency, pump hanger depth, and tubing string based on factors such as the well's dynamic fluid level, crude oil viscosity, water cut, and gas-oil ratio. This optimized combination determines the mechanical recovery parameters, thereby improving the overall system efficiency. This software has now been implemented in every oilfield. Regarding pumping units, after years of testing and application of over 100 models across various oilfields, energy-saving pumping units with advantages such as simple structure, reliability, durability, and low energy consumption have gradually been developed. These include models such as the non-standard walking beam pumping unit, the non-phase crank-type compound balance pumping unit, the pendulum walking beam pumping unit, the friction-reversing pumping unit, and the downward-biased barbell pumping unit. In terms of motors, high (ultra-high) slip motors, dual-speed motors, permanent magnet motors, and variable frequency speed control motors have been widely used to address the load characteristics of pumping units, leading to the formation of the oil and gas industry standard "CJT Series Pumping Unit Energy-Saving Drive Devices" (SY/T5226—2005). For example, since the 11th Five-Year Plan, Daqing Oilfield has implemented energy-saving technological upgrades on over 6,600 wells, including replacing pumping units, motors, and control boxes with energy-saving ones, and implementing energy-saving retrofits for pumping units and motors. These measures have resulted in an average daily energy saving of 25 kWh per well and an average increase in pumping unit system efficiency of 3 percentage points. 3. Natural Gas Venting Recovery Technology: For a long time, domestic oilfields have been in a rolling development phase. During the trial production of individual wells, the natural gas produced had to be vented for extended periods due to the lack of supporting facilities, resulting in the waste of oil and gas resources and pollution of the surrounding environment. To solve the natural gas venting problem, China National Petroleum Corporation (CNPC) has carried out a special governance project and has implemented associated gas recovery projects in key areas such as the Tarim Oilfield, Xinjiang Oilfield, Turpan-Hami Oilfield, Changqing Oilfield, and North China Oilfield. A model has gradually been formed that classifies vented natural gas according to its venting method and the difficulty of recovery, and adopts different schemes and technologies for recovery and utilization for different types of vented natural gas. Relying on the West-to-East Gas Pipeline project, Tarim Oilfield began implementing the "Tarim Oilfield Comprehensive Utilization Plan for Vented Natural Gas" in 2004. The main recovery schemes and technologies include: for vented natural gas caused by the lack of natural gas processing facilities or insufficient facility capacity, measures such as constructing natural gas processing and pressurization devices and laying gas pipelines are used to collect and process the vented natural gas and introduce it into the West-to-East Gas Pipeline; gas-fired power plants are constructed in conjunction with the current load and development plan of the oilfield's power grid; for vented natural gas from remote wells and pilot production wells, skid-mounted CNG units are used for collection, and CNG unloading stations are established at the starting points of each gas pipeline, allowing the gas to enter the West-to-East Gas Pipeline via the existing natural gas transmission network. To date, vented natural gas recovery projects have been carried out in Lunnan Oilfield, Tazhong 4 Oilfield, Yaha 5 condensate gas field, Tazhong Chuanzhu Oilfield, and Kekeya condensate gas field, achieving an annual recovery capacity of 400 million cubic meters of vented natural gas. 4. Crude Oil Ambient Temperature Gathering and Transportation Technology: Most oil wells in eastern my country's oilfields primarily employ high-energy-consuming dual-pipe water-injection and triple-pipe heat-tracing oil gathering processes. In recent years, ambient temperature crude oil gathering and transportation technology has received increasing attention from various oilfields. Each oilfield has conducted extensive research and field trials based on different development stages, crude oil properties, and climatic conditions, resulting in technologies such as single-pipe ambient temperature oil gathering, low-temperature produced fluid free water removal, and centrifugal pump transportation of low-temperature water-bearing crude oil, achieving excellent results. Currently, single-pipe ambient temperature oil gathering technology has been widely applied in more than a dozen oilfields, including Daqing, Jilin, Liaohe, and Xinjiang. In the national standard "Code for Design of Oil and Gas Gathering and Transportation" GB50350-2005, ambient temperature gathering and transportation technology has become a key technology for promotion and application. Since 2003, Daqing Oilfield has implemented unheated production fluid gathering and transportation technology in eight joint stations of the Third and Sixth Oil Production Plants. Forty-one oil transfer stations and 2,377 oil wells have implemented year-round shutdown of heating furnaces and low-temperature water-based unheated oil gathering, with the water temperature generally reduced from 65-70℃ during heating to 30-35℃. From 2003 to 2007, these two oil production plants implemented unheated and cooled oil gathering in 4,394 oil wells, saving a total of 350 million cubic meters of oilfield gas. 5. Energy-saving technology for heavy oil thermal recovery: China National Petroleum Corporation (CNPC) has applied energy-saving technology for heavy oil thermal recovery in the Liaohe and Xinjiang oilfields, major heavy oil producing areas, effectively controlling the growth of energy consumption. Xinjiang Oilfield has conducted technological research and development, implementing a heavy oil extraction energy-saving demonstration project. This project applied six energy-saving technologies, including new high-temperature radiant coatings, flue gas waste heat recovery devices, online hardness monitoring instruments, boiler flue gas excess air monitoring, boiler convection section finned tube hard scale cleaning, and online steam dryness monitoring. Tests showed that steam injection consumption decreased from 86 kg/ton of standard coal equivalent to 81 kg/ton of standard coal equivalent, with a comprehensive gas saving rate exceeding 5% and a water saving rate exceeding 7.5%. Liaohe Oilfield, addressing the challenges of heavy oil produced water treatment and resource utilization, successfully applied deep treatment technology for heavy oil produced water through laboratory and field trials, and is gradually expanding its industrial application. Since 2002, Liaohe Oilfield has built six deep treatment stations for heavy oil produced water using this technology, with two currently under construction. The total treatment capacity is 45,000 cubic meters per day, with produced water replacing clean water and being entirely reused in boilers, achieving recycling. To date, a total of 120 million cubic meters of clean water has been saved, while COD emissions have been reduced by 60,000 tons and BOD emissions by 12,000 tons. 6. Natural Gas Downhole Throttling Technology: In the development and production of natural gas wells, to prevent hydrate formation and blockage of pipelines and equipment, conventional surface throttling processes, such as wellhead heating throttling and wellhead methanol injection high-pressure gathering and transportation, both consume a large amount of energy. Downhole throttling technology places the downhole throttling device at a specific location within the tubing, fully utilizing geothermal temperature to ensure that the gas flow temperature after throttling is higher than the hydrate formation temperature under the pressure conditions after throttling, thus eliminating the need for surface heating and insulation devices. In the second phase of development of the shallow gas reservoir in Baima Penglai Town, Southwest Oil and Gas Field, the adoption of downhole throttling technology and other techniques reduced investment costs by 6 million yuan and fuel costs for the water-jacketed heater by 248,400 yuan per year, demonstrating significant economic benefits. The Sulige Gas Field, characterized by low permeability, low abundance, low pressure, and low production, has adopted an integrated innovation, overall optimization, and modular design model to form a surface gathering and transportation process of "downhole throttling, no wellhead heating or alcohol injection, medium- and low-pressure gas gathering with liquid metering, inter-well connection, ambient temperature separation, two-stage pressurization, and centralized processing," ensuring the large-scale, economical, and effective development of the gas field. 7. High-efficiency and energy-saving equipment (1) High-efficiency three-phase separator. In recent years, many oilfields have conducted extensive and in-depth research on the oil-gas-water separation mechanism and have successively developed three-phase separators suitable for the characteristics of their respective oilfields. The successful application of the high-efficiency three-phase separator dehydration technology has changed the three-stage dehydration process mode of oil and gas treatment, simplified the dehydration process, reduced operating energy consumption, and improved the technical level of crude oil processing stations. For example, the HNS type high-efficiency three-phase separator adopts technologies such as "cyclone pre-degassing, active water washing to accelerate dehydration, and mechanical demulsification to enhance dehydration," which makes the operating effect of the equipment reach the advanced level of similar international equipment, and the processing capacity per unit volume is more than 5 times that of traditional equipment. Not only has it simplified the process and saved investment, but it has also saved energy and reduced consumption, greatly reducing operating costs and has been widely promoted and applied. Daqing, Liaohe and other oilfields have developed a variety of high-efficiency three-phase separation equipment according to different oil properties. (2) Multifunctional treatment device. Daqing, Xinjiang, Liaohe and Changqing oilfields have developed a variety of multifunctional oil and gas treatment devices according to the actual conditions of their respective oilfields. Daqing oilfield has developed a multifunctional treatment device for peripheral "three-low" oilfields. This device is called "five-in-one" and has gas-liquid separation, sedimentation, heating, electric dehydration and buffering functions. Under the conditions of influent liquid water content of more than 85%, chemical dosage of 10mg/L and dehydration temperature of 45℃, the outlet oil contains 0.3% water and the sewage contains 1000mg/L oil. Compared with crude oil gathering and processing stations of the same scale, this device can save 38% of engineering investment, reduce land occupation by 69% and reduce building area by 76%; at the same time, it can also greatly reduce the number of operation and management personnel and maintenance costs, and obtain significant economic and social benefits. To date, the device has been promoted and applied in Daqing Oilfield No. 7 and Hailar, becoming the main crude oil gathering and processing equipment for newly built oilfields in the periphery. The multi-functional processor in Xinjiang Oilfield has functions such as oil and gas separation, crude oil heating, first-stage thermochemical dehydration, second-stage electrochemical dehydration, and hydraulic sand removal. It replaces the complex processes and various equipment in the traditional process, simplifies the process, and achieves better economic benefits. (3) High-efficiency heating furnace. In recent years, in response to the problems of low heating furnace thermal efficiency, high excess air coefficient, high flue gas temperature, and incomplete combustion in oilfield heating systems, various oilfields have done a lot of work to improve the combustion of heating furnaces and increase the efficiency of heating systems. Representative examples include the application of high-efficiency and energy-saving equipment such as vacuum heating furnaces, phase change heating furnaces, hot coal furnaces, and inorganic heat transfer waste heat utilization devices in Jidong, Dagang, and Daqing oilfields. Jidong Oilfield Gaoyi Joint Station was built in 1989 with an annual crude oil processing capacity of 100×104t. The heating system consists of three 4t/h steam boilers and eight 2.32MW tubular heaters. After years of operation, the heaters were inefficient. In 2002, after demonstration, two 1.25MW and one 1.0MW high-efficiency phase change heaters were used to replace the three steam boilers that had been in operation for 14 years. In 2005, the eight 2.32MW tubular heaters were replaced with two 2.0MW phase change heaters and four 2.0MW vacuum heaters. The efficiency of the newly installed phase change heaters and vacuum heaters both reached over 85%. (4) Screw pump oil production technology. Screw pump oil production technology is a highly efficient oil production technology. In its early stages of application, it suffered from poor applicability in various oilfields, resulting in issues such as rod breakage and oil leakage. In recent years, through comprehensive improvements to its process, core technologies and supporting technologies have been developed, including a series of screw pumps with large, medium, and small displacements, a special series of anti-breakage sucker rods, leak-free low-profile drive units, and screw pump well condition analysis, diagnosis, and monitoring. These technologies have effectively met the needs of water-drive and polymer-drive produced fluid lifting. For example, as of September 2006, Daqing Oilfield had 2,249 screw pump wells in use, and this number was increasing by 500 wells per year. Compared with pumping unit wells, the average pump efficiency was increased by 20 percentage points, resulting in significant energy savings. II. The Situation and Tasks (I) Developing energy-saving technologies is a key measure for oil and gas field enterprises to implement national requirements. Since the "Eleventh Five-Year Plan for National Economic and Social Development" clearly stated that resource conservation should be a basic national policy and that the goal of reducing energy consumption per unit of GDP by 20% by the end of the "Eleventh Five-Year Plan" period should be achieved, the country has adopted a series of policies and measures to strengthen energy conservation, which have yielded significant results. However, judging from the situation in the first two years of the 11th Five-Year Plan, the national energy consumption per unit of GDP decreased by only 1.33% in 2006. The situation improved somewhat in 2007, with the national energy consumption per unit of GDP at 1.16 tons of standard coal equivalent per 10,000 yuan, a decrease of 3.66% compared to 2006. This still falls far short of the expected target of the 11th Five-Year Plan, and the energy conservation situation remains very serious. On July 1, 2008, the State Council convened a meeting of the Leading Group for Energy Conservation and Emission Reduction to hear a report on the progress of energy conservation and emission reduction work in 2007 and to arrange the work for 2008. The meeting proposed twelve key tasks for energy conservation and emission reduction, among which the sixth point was to accelerate the development and promotion of energy conservation and emission reduction technologies, requiring the promotion of a number of major energy conservation and emission reduction technologies with great potential and wide application in key industries and fields. China National Petroleum Corporation's (CNPC) energy conservation target for the 11th Five-Year Plan was to achieve energy savings of 6.6 million tons of standard coal equivalent, with oil and gas field operations responsible for nearly half of this. To achieve the national energy conservation and emission reduction targets, CNPC adopted a two-pronged approach of energy management and energy-saving technologies, achieving good results in the first two years of the 11th Five-Year Plan. According to statistics, oil and gas field enterprises achieved a cumulative energy saving of 1.67 million tons of standard coal equivalent in the first two years of the 11th Five-Year Plan, completing nearly half of the target in two-fifths of the time. The "Ten Major Energy-Saving Projects" launched by China National Petroleum Corporation (CNPC) at the beginning of the 11th Five-Year Plan played a significant role. In the oil and gas field sector, since 2006, a special investment of 2.4 billion yuan has been allocated for energy-saving projects, implementing associated gas recovery and utilization, energy system optimization, and improving equipment energy efficiency, with an estimated energy saving capacity of 1.2 million tons of standard coal equivalent per year. Currently, the energy saving capacity has reached 510,000 tons of standard coal equivalent per year, generating economic benefits of 440 million yuan per year. In the coming years, oil and gas field operations will continue to explore the potential for energy saving through technological means, summarizing the implementation experience of energy-saving projects in recent years, evaluating and selecting advanced energy-saving technologies, increasing their promotion and application, and further improving the contribution rate of technological energy saving. It is expected that approximately 2.4 billion yuan will be invested in special energy-saving projects during the remainder of the 11th Five-Year Plan period to promote the in-depth implementation of the "Ten Major Energy-Saving Projects." (II) Developing energy-saving technologies is an important way for oil and gas field enterprises to transform their growth model. Based on a thorough study of the spirit of the 17th National Congress of the Communist Party of China, China National Petroleum Corporation (CNPC) proposed that its goal for the coming period is to become a comprehensive international energy company. At the Group's 2008 work conference, General Manager Jiang Jiemin proposed that by 2015, the overall framework of a comprehensive international energy company would be formed. One of the key deployments was a significant transformation of the economic development model: a basically complete technological innovation system, a substantial increase in the contribution rate of science and technology, the conversion rate of scientific research results, and the level of informatization, and leading the central enterprises in energy conservation and emission reduction. Although significant progress has been made in energy-saving technologies in oil and gas fields in recent years, overall, the difficulty of energy conservation and consumption reduction in oil and gas fields is increasing, and problems such as relatively high energy consumption per unit of production still exist. Therefore, the development potential of energy-saving technologies in oil and gas fields is great. First, as the major oilfields in the east enter the middle and late stages of development, the increasing water cut leads to a continuous increase in fluid production and injection, a decrease in oil production per well, and a year-on-year increase in the total number of oil and water wells. This makes cost control more difficult, and increases the consumption of water, electricity, and gas. The number of heavy oil fields entering high-cycle steam injection phases will increase annually, but the effectiveness of steam injection thermal recovery will gradually deteriorate, the oil-steam ratio will further decline, and the number of high-energy-consuming steam-driven and SAGD oil production blocks will increase, resulting in an overall upward trend in unit production energy consumption. Newly developed oil and gas fields are mostly low-grade, low-abundance, low-yield, low-permeability, and heavy oil, which also contributes to the continuous increase in energy consumption. Second, with the continued development of oil and gas fields, the oil and gas field system is becoming increasingly large. The existing surface engineering system includes more than 160,000 oil and water wells, approximately 11,000 stations of various types, more than 20,000 heating furnaces and boilers of various types, and more than 150,000 kilometers of various pipelines. It is estimated that more than 10,000 new wellhead devices, over 1,000 stations, and more than 10,000 kilometers of pipelines will be added annually. Although a number of high-consumption and inefficient equipment have been phased out, problems such as equipment aging, corrosion and scaling, and unbalanced load matching in surface engineering systems still exist, and the difficulty of optimizing and adjusting various production and operation systems is gradually increasing. As an important part of building a comprehensive international energy company, energy conservation and emission reduction is a breakthrough and important lever for CNPC to transform its growth model. For newly developed oil and gas fields, the entire process of oil and gas production—"reservoir engineering, oil production engineering, and surface engineering"—must be considered holistically, and integrated oil and gas development should be implemented. While effectively improving the conversion and extraction efficiency of oil and gas resources, system energy should be rationally matched to improve energy utilization efficiency. For old oil fields, secondary development projects should be vigorously promoted. Through the organization and implementation of the "Ten Major Energy Conservation Projects," system optimization, shutdown and elimination of high-energy-consuming devices, wells, and stations, continuous progress in energy-saving technologies should be made to achieve continuous improvement in comprehensive energy efficiency. III. Outlook on Energy-Saving Technologies in Oil and Gas Fields (I) Development Dynamics of Energy-Saving Technologies in Oil and Gas Fields at Home and Abroad 1. Emphasis on the Application of Advanced Energy-Saving Technologies In the field of oil and gas fields, large international oil companies are actively adopting some advanced technologies to improve the efficiency of oil and gas field development, reduce energy consumption, and control greenhouse gas emissions. The advanced technologies adopted mainly include: (1) Downhole separation technology. The produced liquid (gas) is separated in the formation or wellbore by mechanical or natural methods so that hydrocarbons flow to the surface and water is directly returned or pumped into the underground water injection layer. Compared with the production water production and reinjection, it has the advantages of significantly reducing the amount of surface produced water, the production water lift, treatment, sewage discharge and related environmental protection costs, and increasing oil production. Downhole separation technology is being piloted worldwide. (2) Advanced Process Control (APC) technology. Based on basic automation unit control, PID control and distributed control system (DCS), it realizes data integration, process operation optimization and production safety monitoring, accident alarm processing and other functions. (3) Recycling of oilfield produced water. Oilfield produced water has a higher temperature than groundwater. After treatment, it can be recycled, utilizing some of the heat and reducing the heat required to generate steam. This reduces fuel consumption during oilfield extraction and saves a large amount of freshwater resources, solving the environmental pollution problem caused by oilfield produced water discharge. (4) High-efficiency heat preservation technology. In oil and gas gathering and transportation and heavy oil thermal recovery processes, there are many heat-using processes. The widespread application of high-efficiency heat preservation technology has greatly improved the efficiency of oilfield extraction and energy use. For example, the Kern River oilfield in the United States installed high-temperature centralizers on the heavy oil extraction steam injection pipeline, used high-efficiency heat-insulating pipes and kept the cylinder dry, ensuring that wellbore losses were reduced from the usual 18% to 13%. British Petroleum Exploration Company applied vacuum heat-insulated tubing technology in the Troika oilfield, keeping the oil flow at the wellhead at a high temperature and greatly extending the cooling time of the oil flow in the insulated oil production pipeline. Currently, super-insulated oil pipes are widely used abroad. They are manufactured using a multi-layer heat shield similar to a low-temperature insulation container and vacuuming. Their radial apparent thermal conductivity can be reduced to 0.003 W/(m·K). (5) Digital technology of oil fields. In the last decade, the term "digital oil field" has emerged to describe the ability to monitor and manage all production and operation of an oil field in real time or near real time through information technology, overcoming geographical limitations, and integrating underground production with surface operation metering. Recently, the online edition of the American "Petroleum Technology Magazine" published an article by TedMoon, proposing "using digital technology to obtain the next trillion barrels of oil". 2. Focus on comprehensive energy utilization. Cogeneration is an effective way to comprehensively utilize energy in oil field production, realizing the rational cascade utilization of energy from high grade to low grade, thus achieving high efficiency and energy saving. In a cogeneration system, depending on the system capacity and system configuration, its comprehensive thermal efficiency can be as high as 70%-90%. Compared with separate heat and power production, in order to provide users with the same amount of electricity and heat, the final total thermal efficiency of cogeneration is 30% higher. A higher overall thermal efficiency can be achieved by using a gas turbine combined with a waste heat boiler in a cogeneration system. Foreign oilfields have widely adopted gas-fired cogeneration in heavy oil thermal recovery, which involves large-scale heat consumption. For example, the Kern River oilfield in the United States has evolved from initial bottom-hole electric heating to oil/gas-fired heating boilers, and then to steam generation through cogeneration. The Kern River oilfield began fully adopting cogeneration units in 1987. The two cogeneration stations have a total of eight steam generators, supplying 39,000 tons of steam per day. Simultaneously, the generated electricity is transmitted to surrounding consumers, bringing economic benefits to the oilfield. By employing efficient insulation technology and steam dryness control technology, the steam dryness injected into the formation has reached approximately 90%, thereby increasing heavy oil production and reducing energy consumption in heavy oil thermal recovery. 3. Emphasis on the Utilization of New and Renewable Energy Sources In recent years, there have been numerous reports from abroad regarding the application of new and renewable energy sources such as solar energy and geothermal energy in oilfields, such as solar energy applications. After adopting solar thermal diode technology, a 32km long heavy oil pipeline in Venezuela increased the oil transport temperature from 28℃ to 60℃, increasing the transport capacity by 17%. Several pipelines in Kuwait, Indonesia, Malaysia, and other countries and regions are also undergoing trials. Jordan used solar collectors to heat fuel oil in a Middle Eastern power plant, successfully maintaining the fuel oil system at a constant temperature above 50℃, thus saving 5%–8% of energy consumption. In 2003, Chevron established a 500kW solar photovoltaic system in California. This demonstration project is the largest solar photovoltaic system installed in the United States and the world's largest series of amorphous silicon solar technology. This system, in conjunction with the power system, provides electricity to the well pump units and oil processing plants in the Midway Sunset oil field. (II) Outlook for Energy-Saving Technologies in Oil and Gas Fields Oil and gas field production is a massive system engineering project that closely integrates reservoir engineering, production engineering, and surface engineering, requiring coordination among various disciplines. The development of energy-saving technologies must be closely integrated with production processes. Advances in production process technology promote energy conservation and consumption reduction, while the development of energy-saving technologies promotes improvements in production processes. The following are the energy-saving technology requirements for various processes in oil and gas field production. 1. Overall Optimization Technology for Surface and Subsurface Operations: Oil and gas field development is a systematic project involving reservoir description, well network layout adjustment, production process selection, and surface oil and gas gathering and processing technologies. To achieve energy-efficient and high-performance development of oil and gas fields, system optimization and source control are key. First, it is necessary to start with in-depth reservoir detailing, comprehensively optimizing well placement and well type schemes based on geological research and reservoir distribution, and proactively planning surface engineering. Second, it is essential to summarize the experience of "simplifying old and optimizing new," rationally determining the stable production period and construction scale, fully considering the matching of new and efficient technologies and equipment, and the seamless utilization of existing surface facilities to improve the utilization rate and load factor of surface facilities. Third, it is crucial to establish a coordination mechanism between surface and subsurface operations for comprehensive optimization. Developing overall optimization technology for surface and subsurface operations in oil and gas development aims to establish a system design model that integrates advanced technologies in reservoir description, development deployment, production process design, and surface engineering design, providing methodology and technical support for the secondary development of old oilfields and the overall development of new oilfields. 2. Energy-saving technologies for mechanical pumping systems Mechanical pumping systems are the main power systems in oilfields, accounting for more than 45% of the power consumption in oilfield production. To improve the efficiency of mechanical pumping systems, energy-saving technologies should be developed in a comprehensive manner, including parameter optimization design, pump rods, drive devices, and power distribution. (1) Pumping unit system efficiency optimization design software. By testing the pumping unit well dynamometer diagram, dynamic fluid level, production parameters, and working parameters of surface equipment, and combining sensitivity analysis of parameters such as crude oil physical properties, well structure parameters (inclined and vertical wells), pumping parameters, and rod and tubing string combinations, the operating parameters (stroke, stroke rate, pump diameter, pump depth) and matching motor power and other energy-saving devices are optimized to improve the efficiency of the pumping unit system. (2) Pumping unit. Develop low-profile, front-mounted, compact long-stroke pumping units without walking beams and hydraulic cylinder type and increased stroke walking beam type pumping units that can adapt to the pumping of crude oil with high water content, sand content, gypsum content, paraffin content, and gas content, as well as the exploitation of heavy oil low-permeability oil layers; to meet the needs of pumping in vertical wells, deviated wells, directional wells, cluster wells, and horizontal wells, develop deviated well and cluster well pumping units, dual-well balanced pumping units, compact pumping units, etc.; develop new energy-saving pumping units such as heterogeneous type, front-mounted type, large ring type, wheel type, fiberglass rod, and six-link type. (3) Electric submersible pumps and screw pumps. Develop high-efficiency electric submersible pumps and screw pumps that are adaptable to different well depths, different displacements, and reliable operation, as well as downhole drive screw pumps and screw pump special frequency conversion drive devices, etc. (4) Pumping unit drive devices. Develop energy-saving drive devices such as ultra-high slip motors, frequency conversion speed control motors, dual power motors, and rare earth permanent magnet synchronous motors. 3、油田采出水余热利用配套技术我国大部分油田都已进入开发中后期，油田采出采出水水量越来越大，采出水总量在几亿立方米以上，常规油田采出水温度为38℃～43℃、稠油油田为60℃～65℃，蕴藏着大量的热能。油田采出水的余热回收利用潜力巨大。 大庆、辽河等油田已经开展热泵回收采出水余热技术试验，用于站内生活采暖，但这仅利用了很小一部分油田采出水的能量。若采用热泵技术将油田采出水的热量回收应用于原油集输、处理、储运等各种工艺，取代原有加热装置，将收到明显的经济效益和社会效益。 4、油气集输节能技术油气集输包括集油、油气水分离、污水处理、原油外输等环节，工艺复杂。随着油田开发的深入，油、气、水产量和产出液物理化学性质不断变化，系统规模日益扩大，节能技术发展需求迫切，主要有： （1）集油技术。深入开展环状集油和不加热集油技术界限的研究，推广不加热集油、密闭集输等低能耗工艺技术。 （2）油气混输。推广应用油气混输技术，解决边远区块进不了系统、局部区域集输回压高的问题，进一步提高油气集输密闭率。吸收引进国外混输泵技术，提高国内混输泵的可靠性和适应性。 （3）油气处理。推广应用新型高效油气处理技术、污水处理技术、输油泵变频调速技术、加热炉新型高效节能火嘴和自动化控制技术，加强低温破乳剂的开发和应用，改进原油脱水工艺，降低原油处理运行能耗。 5、稠油热采配套节能技术我国稠油产量逐步提高，但是稠油开采能耗远高于常规原油开采，注汽开采需要消耗大量的燃料，其中大多为天然气和原油。据统计，2007年中国石油的稠油产量约占总产量的10%，但是稠油生产能耗却占油气田生产总能耗的20%以上，提高稠油生产节能技术水平，降低稠油开采能耗的意义显得尤为重大。 （1）注汽锅炉节能技术。发展高效燃油替代技术、稠油区块燃气（煤）热电联产技术、蒸汽过热技术和锅炉除垢清灰技术，提高能源综合利用水平。 （2）蒸汽管线和蒸汽调控技术。优化注汽管网布置，合理确定注汽半径，减小管道热损失。对于蒸汽管道及支座保温，发展高效保温材料，优化保温结构。对于蒸汽调节，发展简单可靠的蒸汽计量、分配和调控装置，保证每口井的注汽速度、蒸汽干度，从而提高油井的热采效果。 （3）井筒加热和高效保温隔热技术。对于稠油降粘，发展化学降粘剂替代电加热、高效空心杆电加热技术。对于井筒保温，发展高效隔热管、真空隔热油管技术，减少蒸汽和油流在井筒中的热损失。 6、新能源与可再生能源我国油气田大多地处沙漠、高原，具有丰富的太阳能、风能、地热能等新能源和可再生能源资源，如何合理开发应用成为越来越迫切的问题。 （1）太阳能。西北地区油气田日照强烈，长输管道无人职守的中间站上大多以太阳能电池作电源，新疆等油田也已经开展太阳能装置在油田各领域的应用试验。光—热转换应用研究的成果已广泛应用于民用太阳能热水器，需要进一步加强在油田生产加热工艺环节的应用;光—电转换应用研究的重点是要提高光电转化效率及降低成本。 （2）地热能。地热能利用已是一种成熟技术。华北、大港等油田具有丰富的地热资源，也已经开展了地热能利用的相关工业试验，取得了较好的效果。需要进一步总结经验，加强直接利用中高温地热水替代加热炉技术应用，同时发展地热源热泵应用技术，合理梯级利用地热资源。