Research progress and potential of new enhanced oil recovery methods in oilfield development

This paper reviews the basic research means for oilfield development and also the researches and tests of enhanced oil recovery(EOR)methods for mature oilfields and continental shale oil development,analyzes the problems of EOR methods,and proposes the relevant research prospects.The basic research means for oilfield development include in-situ acquisition of formation rock/fluid samples and non-destructive testing.The EOR methods for conventional and shale oil development are classified as improved water flooding(e.g.nano-water flooding),chemical flooding(e.g.low-concentration middle-phase micro-emulsion flooding),gas flooding(e.g.micro/nano bubble flooding),thermal recovery(e.g.air injection thermal-aided miscible flooding),and multi-cluster uniform fracturing/water-free fracturing,which are discussed in this paper for their mechanisms,approaches,and key technique researches and field tests.These methods have been studied with remarkable progress,and some achieved ideal results in field tests.Nonetheless,some problems still exist,such as inadequate research on mechanisms,imperfect matching technologies,and incomplete industrial chains.It is proposed to further strengthen the basic researches and expand the field tests,thereby driving the formation,promotion and application of new technologies.

Development characteristics and controlling factors of fractures in lacustrine shale and their geological significance for evaluating shale oil sweet spots in the third member of the Shahejie Formation in the Qikou Sag, Bohai Bay Basin

Natural fractures are critical for shale oil and gas enrichment and development. Due to the extremely high heterogeneity of shale, the factors controlling the formation of internal fractures, especially horizontal fractures, remain controversial. In this study, we integrate thin section analysis and microcomputed tomography(CT) data from several lacustrine shale samples from the third member(Es3) of the Shahejie Formation, Qikou Sag, Bohai Bay Basin, to assess the fractures in detail. The goal is to reveal the development characteristics, controlling factors, and geological significance for evaluating sweet spots in a shale oil play. The fractures in the Es3contain high-angle structural and horizontal bed-parallel fractures that are mostly shear and extensional. Various factors influence fracture development,including lithofacies, mineral composition, organic matter content, and the number of laminae. Structural fractures occur predominantly in siltstone, whereas bed-parallel fractures are abundant in laminated shale and layered mudstone. A higher quartz content results in higher shale brittleness, causing fractures, whereas the transformation between clay minerals contributes to the development of bedparallel fractures. Excess pore pressure due to hydrocarbon generation and expulsion during thermal advance can cause the formation of bed-parallel fractures. The density of the bed-parallel and structural fractures increases with the lamina density, and the bed-parallel fractures are more sensitive to the number of laminae. The fractures are critical storage spaces and flow conduits and are indicative of sweet spots. The laminated shale in the Es3with a high organic matter content contains natural fractures and is an organic-rich, liquid-rich, self-sourced shale play. Conversely, the siltstone, massive mudstone, and argillaceous carbonate lithofacies contain lower amounts of organic matter and do not have bed-parallel fractures. However, good reservoirs can form in these areas when structural fractures are present and the source, and storage spaces are separated.

Iteration and evaluation of shale oil development technology for continental rift lake basins

By benchmarking with the iteration of drilling technology,fracturing technology and well placement mode for shale oil and gas development in the United States and considering the geological characteristics and development difficulties of shale oil in the Jiyang continental rift lake basin,East China,the development technology system suitable for the geological characteristics of shale oil in continental rift lake basins has been primarily formed through innovation and iteration of the development,drilling and fracturing technologies.The technology system supports the rapid growth of shale oil production and reduces the development investment cost.By comparing it with the shale oil development technology in the United States,the prospect of the shale oil development technology iteration in continental rift lake basins is proposed.It is suggested to continuously strengthen the overall three-dimensional development,improve the precision level of engineering technology,upgrade the engineering technical indicator system,accelerate the intelligent optimization of engineering equipment,explore the application of complex structure wells,form a whole-process integrated quality management system from design to implementation,and constantly innovate the concept and technology of shale oil development,so as to promote the realization of extensive,beneficial and high-quality development of shale oil in continental rift lake basins.

Shale oil development techniques and application based on ternary-element storage and flow concept in Jiyang Depression,Bohai Bay Basin,East China

The ternary-element storage and flow concept for shale oil reservoirs in Jiyang Depression of Bohai Bay Basin,East China,was proposed based on the data of more than 10000 m cores and the production of more than 60 horizontal wells.The synergy of three elements(storage,fracture and pressure)contributes to the enrichment and high production of shale oil in Jiyang Depression.The storage element controls the enrichment of shale oil;specifically,the presence of inorganic pores and fractures,as well as laminae of lime-mud rocks,in the saline lake basin,is conducive to the storage of shale oil,and the high hydrocarbon generating capacity and free hydrocarbon content are the material basis for high production.The fracture element controls the shale oil flow;specifically,natural fractures act as flow channels for shale oil to migrate and accumulate,and induced fractures communicate natural fractures to form complex fracture network,which is fundamental to high production.The pressure element controls the high and stable production of shale oil;specifically,the high formation pressure provides the drive force for the migration and accumulation of hydrocarbons,and fracturing stimulation significantly increases the elastic energy of rock and fluid,improves the imbibition replacement of oil in the pores/fractures,and reduces the stress sensitivity,guaranteeing the stable production of shale oil for a long time.Based on the ternary-element storage and flow concept,a 3D development technology was formed,with the core techniques of 3D well pattern optimization,3D balanced fracturing,and full-cycle optimization of adjustment and control.This technology effectively guides the production and provides a support to the large-scale beneficial development of shale oil in Jiyang Depression.

Floating Production Platforms and their Applications in the Development of Oil and Gas Fields in the South China Sea

This paper studies the current available options for floating production platforms in developing deepwater oil fields and the potential development models of future oil and gas exploration in the South China Sea. A detailed review of current deepwater platforms worldwide was performed through the examples of industry projects, and the pros and cons of each platform are discussed. Four types of platforms are currently used for the deepwater development: tension leg platform, Spar, semi-submersible platform, and the floating production system offloading. Among these, the TLP and Spar can be used for dry tree applications, and have gained popularity in recent years. The dry tree application enables the extension of the drilling application for fixed platforms into floating systems, and greatly reduces the cost and complexity of the subsea operation. Newly built wet tree semi-submersible production platforms for ultra deepwater are also getting their application, mainly due to the much needed payload for deepwater making the conversion of the old drilling semi-submersible platforms impossible. These platforms have been used in different fields around the world for different environments; each has its own advantages and disadvantages. There are many challenges with the successful use of these floating platforms. A lot of lessons have been learned and extensive experience accumulated through the many project applications. Key technologies are being reviewed for the successful use of floating platforms for field development, and potential future development needs are being discussed. Some of the technologies and experience of platform applications can be well used for the development of the South China Sea oil and gas field.

New progress and prospect of oilfields development technologies in China

As technologies advance in oilfield development, mature oilfields are able to keep sustainable production and complex oilfields difficult to produce in the past are put into production efficiently. In this work, new progresses of main development technologies for medium-high permeability and high water cut, low permeability, heavy oil, complex faulted block and special lithology reservoirs in the past decade, especially those international achievements made in enhanced oil recovery, were summarized, the key problems and major challenges that different oilfields are facing were analyzed, and the development route and direction of three-generation technologies were proposed as "mature technology in industrialized application, key technology in pilot test and innovative technology for backup". The key research contents should focus on:(1) Fine water flooding and chemical flooding for mature oilfields, improving oil recovery after chemical flooding, and gas flooding for low permeability reservoirs must be researched and tested in field further.(2) Study on subversive technologies like nanometer smart flooding, in-situ upgrading and injection and production through the same well should be strengthened.(3) EOR technologies for low oil price, new fields(deep sea, deep layer, unconventional reservoirs etc.) and highly difficult conditions(the quaternary recovery after chemical flooding, tertiary recovery in ultra-low permeability reservoirs) should be stocked up in advance. The development cost must be lowered significantly through constant innovation in technology and reservoir management to realize sustainable development of oilfields.

Development characteristics and quantitative prediction of reservoir fractures in the Chaoyanggou oil field

The Chaoyanggou oil field is a fractured low-permeability reservoir, where the distribution of oil and gas is controlled by the distribution and development of fractures.Based on outcrop, drilling core, thin section and log data, the development characteristics of fractures in this area are described.On this basis, the degree of fracture development was predicted by quantitative analysis of fracture strength and numerical simulation.The result shows that four groups of structural fractures, i.e., in near NS, and EW directions and in due NW and NE directions, were developed in the reservoir, with the nearly NS and EW fractures dominant, which are the along bedding decollement fractures formed by compressive folding action, while low angle shear fractures are related to thrusts.These fractures are mainly formed in the reversed tectonic stage at the end of the Mingshui formation during the Cretaceous period.The degree of fracture development is controlled by such factors as lithology, stratum thickness, faults, folds and depth.The fractures are developed with a clear zonation and are best developed in the northern zone, moderately developed towards the south and poorly developed in the middle zone.These prediction results are in good agreement with interpretation results from logs.

Technological progress and development directions of PetroChina overseas oil and gas field production

This study reviews the development history of PetroChina’s overseas oil and gas field development technologies, summarizes the characteristic technologies developed, and puts forward the development goals and technological development directions of overseas business to overcome the challenges met in overseas oil and gas production. In the course of PetroChina’s overseas oil and gas field production practice of more than 20 years, a series of characteristic technologies suitable for overseas oil and gas fields have been created by combining the domestic mature oil and gas field production technologies with the features of overseas oil and gas reservoirs, represented by the technology for high-speed development and stabilizing oil production and controlling water rise for overseas sandstone oilfields, high efficiency development technology for large carbonate oil and gas reservoirs and foamy oil depletion development technology in use of horizontal wells for extra-heavy oil reservoirs. Based on in-depth analysis of the challenges faced by overseas oil and gas development and technological requirements, combined with the development trends of oil and gas development technologies in China and abroad, overseas oil and gas development technologies in the future are put forward, including artificial intelligence reservoir prediction and 3 D geological modeling, secondary development and enhanced oil recovery(EOR) of overseas sandstone oilfields after high speed development, water and gas injection to improve oil recovery in overseas carbonate oil and gas reservoirs, economic and effective development of overseas unconventional oil and gas reservoirs, efficient development of marine deep-water oil and gas reservoirs. The following goals are expected to be achieved: keep the enhanced oil recovery(EOR) technology for high water-cut sandstone oilfield at international advanced level, and make the development technology for carbonate oil and gas reservoirs reach the international advanced level, and the development technologies for unconventional and marine deep-water oil and gas reservoirs catch up the level of international leading oil companies quickly.

Study on the Environmental Impact of Oil and Gas Field Development on the Ecological Red Line Area

To cooperate with the five ministries and commissions of the state to carry out joint investigation on the environmentally sensitive areas involved in oil and gas exploration and development,for the problems found in survey,containing complex type and numerous amount of ecologically sensitive space and ecological red line involved in oil and gas field enterprises,scientific nature of delimitation,lack of strong support of laws and regulations for forced withdrawal of oil and gas production facilities in these areas,some countermeasures and suggestions were proposed,such as further evaluating and combing scope and functional zoning of existing environmentally sensitive areas and ecological red lines,treating differently,enhancing pertinence of prohibition in ecologically sensitive regions,declining blindness of the withdrawal of oil and gas facilities in environmentally sensitive areas,strengthening seriousness of approval of exploration and mining rights of oil and gas resources,and establishing strategic reserve exploration and hierarchical development mechanism. Moreover,oil and gas field enterprises should integrate more efforts to ① accelerate to find out the current situation of environmental quality,② adhere to developing in protection,and protecting in development,③ increase attention and participation strengthen of providing technical support for national oil and gas exploration and development strategy evaluation,④ accelerate communication and docking with local governments on the ecological red line,⑤ actively strive to be included in the positive list management of local governments,⑥ accelerate to establish and perfect primary database of oil and gas production and facilities construction,and ⑦ document management information system of the ecological red line.

Improving Light Oil Yield, an Important Way to the Sustainable Development of Petroleum

Oil resources are non- renewable and the utilization of oil resources should be sustainable andrational. Oil processing industry must, to the maximum extent, produce liquid transportation fuel and chemi-cal feedstocks, which can hardly be replaced by other forms of energy. Restructuring oil refineries in China,developing hydrocracking technologies and improving light oil yield are the significant means to achievethe sustainable development of petroleum processing industry.

Subdynamic Programming Optimization Model on Oil Field Development Program

Taking the formulation of the Daqing Oil. fived five-year development plan as the background, this paper puts forward the concept of dynamic programming with aftereffects and gives the principle of suboptimality as its approximate solution. By using this principle an oil field development subdynamic programming model has been made and the oil field development program based on this model has achieved obvious economic benefits.

Development technologies for Triassic Chang 7 shale oil in Ordos Basin: A case study of Qingcheng Oilfield, NW China

The reservoirs in the seventh member of the Triassic Yanchang Formation (Chang 7 Member) in the Qingcheng Oilfield of the Ordos Basin are characterized by thin sandbody, tight rocks, high heterogeneity, low formation pressure coefficient, and complex geomorphology. Through the efforts in the stages of exploration, appraisal, pilot testing and development, a series of key technologies have been formed, including “sweet spot” optimization, differentiated three-dimensional well deployment, fast drilling and completion of large-cluster horizontal well, intensively-staged volume fracturing in long horizontal well, and optimization of rational production system. Furthermore, a production organization mode represented by factory-like operations on loess platform has been implemented. Application of these technologies has enabled to significantly improve the single-well production of the Qingcheng Oilfield, reduce the investment cost, and realize a large-scale and beneficial development at a full cost below $55 per barrel. In 2022, the annual production of Chang 7 shale oil in the Ordos Basin reached 221×10^(4) t, accounting for 70% of the annual shale oil production of China. The practice of development technologies in the Qingcheng Oilfield provides valuable references for efficient development of continental shale oil.

Low cost development strategy for oilfields in China under low oil prices

By reviewing the challenges in the development of oilfields in China under low oil prices,this study analyzes the root causes of cost rising,put forwards the low cost oilfield development strategy and specific paths to realize the strategy,and predicts the development potential and prospect of oilfields in China.In addition to the low grade of the reservoir and high development maturation,the fundamental reasons of development full cost rising of oilfields in China are as follows:(1)Facing the problem of resources turning poorer in quality,we have built production capacity at a pace too fast before making enough technical and experimental preparation;(2)technical engineering service model leads to high service cost;(3)team of oil development expertise and matched engineering system cannot satisfy the technical requirements of stabilizing oil production,controlling water cut and fine development.To realize development at low cost,the core is to increase economic recoverable reserves.The concrete paths include:(1)to explore the"Daqing oilfield development culture",improve the ability of leaders in charge of development,and inspire potential of staff;(2)to improve the ability of reservoir dynamics control,and implement precise development by following scientific principles;(3)to speed up integration of water flooding and enhanced oil recovery(EOR)and technological upgrading in order to enhance oil recovery;(4)to innovate key techniques in gas flooding and accelerate the industrial popularization of gas flooding;(5)to break the related transaction barriers and create new management models;and(6)to collaboratively optimize strategic layout and cultivate key oil bases.Although oilfield development in China faces huge challenges in cost,the low-cost development strategy will succeed as long as strategic development of mature and new oil fields is well planned.The cores to lower cost are to control decline rate and enhance oil recovery in mature oil fields,and increase single well productivity through technical innovation and improve engineering service efficiency through management innovation in new oil fields.

Development of High Viscous Oil in Sandstone Reserviors During the High Water Cut Stage，Gudao Oilfield

The oi!bearing area of Gudao Oilfield covers 80.9 square kilometers.with 373 million tons of oil in place.It is a large drape anticlinal.Neogene Gu-dao Formation is main oil-beraing reservoir devel-oped with dip gentle from 30'to 1°30'in general.The main oil-bearing sequences can be divided into 6 sand groups and 34 layers in detail.in which the Ng°-Ng°sand groups are the main payzones in which oil in place accounts for 97.2%of the total.

Development characteristics, models and strategies for overseas oil and gas fields

Based on about 20 years of accumulated experience and knowledge of oil and gas field development in overseas countries and regions for China's oil companies, the development features, ideas, models and plan designing strategies of overseas oil and gas fields were comprehensively summarized. Overseas oil and gas field development has ten major features, such as non-identity project resource, diversity of contract type, complexity of cooperation model, and so on. The overseas oil and gas field development aims at the maximization of production and benefit during the limited contract period, so the overseas oil and gas field development models are established as giving priority to production by natural energy, building large-scale production capacity, putting into production as soon as possible, realizing high oil production recovery rate, and achieving rapid payback period of investment. According to the overseas contract mode, a set of strategies for overseas oil and gas field development plans were made. For tax systems contracts, the strategy is to adopt the mode of "first fat and then thinner, easier in the first and then harder", that is, early investment pace, production increase rate, development workload and production were decided by the change of tax stipulated in the contract. For production share contracts, the strategy is to give priority to high production with a few wells at a high production recovery rate to increase the cost-oil and shorten the period of payback. For technical service contracts, the strategy is that the optimal production target and workload of the project were determined by the return on investment, so as to ensure that the peak production and stable production periods meet the contract requirements.

Research on Techniques for Rolling Exploration and Development and Application to Dongying Oilfield

ＲｅｓｅａｒｃｈｏｎＴｅｃｈｎｉｑｕｅｓｆｏｒＲｏｌｌｉｎｇＥｘｐｌｏｒａｔｉｏｎａｎｄＤｅｖｅｌｏｐｍｅｎｔａｎｄＡｐｐｌｉｃａｔｉｏｎｔｏＤｏｎｇｙｉｎｇＯｉｌｆｉｅｌｄＤｕＸｉａｎｇｙｕｅａｎｄＳｕｎＬｏｎｇｄｅＫｅｙｗｏｒｄｓ：Ｏｉｌｆｉｅｌ...

Development of the Extra-low Permeability Oilfield of Ansai

ＤｅｖｅｌｏｐｍｅｎｔｏｆｔｈｅＥｘｔｒａ－ｌｏｗＰｅｒｍｅａｂｉｌｉｔｙＯｉｌｆｉｅｌｄｏｆＡｎｓａｉ￥ＨｕＷｅｎｒｕｉ（ＳｅｎｉｏｒＥｎｇｉｎｅｅｒ，ＣｈａｎｇｑｉｎｇＰｅｔｒｏｌｅｕｍＥｘｐｌｏｒａｔｉｏｎＢｕｒｅａｕ）Ｋｅｙｗｏｒｄｓ：Ｏｉｌ...

Study on Ground Engineering and Management of Carbonate Oil Field A under Rolling Development Mode

Carbonate rock has the characteristics of complicated accumulation rules,large-scale development,high yield but unstable production.Therefore,the management and control of surface engineering projects of carbonate rock oil and gas reservoirs faces huge difficulties and challenges.The construction of surface engineering should conform to the principle of integrated underground and ground construction and adapt to the oilfield development model.This paper takes the newly added area A of the carbonated oil field as an example to study the ground engineering under the rolling development mode and aims to provide the constructive ideas for the surface engineering under rolling development mode.The overall regional process design adheres to the design concept of"environmental protection,efficiency,and innovation",strictly follows the design specifications,and combines reservoir engineering and oil production engineering programs,oil and gas physical properties and chemical composition,product programs,ground natural conditions,etc.According to the technical and economic analysis and comparison of area A,this paper has worked out a suitable surface engineering construction,pipeline network layout and oil and gas gathering and transportation plan for area A.Some auxiliary management recommendations are also proposed in this paper,like sand prevention management and HSE management for carbonate reservoirs.