基金项目：中国石油集团软科学研究课题（中油研２０２２０１２３４）；中国石油炼油与化工分公司科技课题（ＡＹＬＨ２０２２２１１）；兰州石化公司碳达峰及碳减排路径实用技术研究（２０２１３８４２）。第一作者：李鸿莉，１９９４年毕业于西南大学环境科学专业，硕士，高级工程师，现在中国石油天然气股份有限公司兰州石化分公司从事环保技术研究工作。通信地址：甘肃兰州西固区玉门街１０号，７３００６０。Ｅｍａｉｌ：ｌｉｈｏｎｇｌｉ＠ｐｅｔｒｏｃｈｉｎａ．ｃｏｍ．ｃｎ。通讯作者：徐文佳，２０１０年毕业于北京大学环境科学专业，硕士，高级工程师，现在中国石油集团安全环保技术研究院有限公司从事温室气体减排利用方面的研究工作。通信地址：北京市昌平区黄河北街１号院１号楼，１０２２０６。Ｅｍａｉｌ：ｓｋｙｘｗｊ＠１６３．ｃｏｍ。
“双碳”背景下石化企业转型现状和趋势李鸿莉１ 逄淑君２ 徐文佳３，４ 刘红彬４，５
（１．中国石油天然气股份有限公司兰州石化分公司；２．机械工业环保产业发展中心；３．石油石化污染物控制与处理国家重点实验室；４．中国石油集团安全环保技术研究院有限公司；５．中国石油大学（北京））
摘 要 国家自２０２１年起出台了一系列政策、规划和文件推动石化行业“双碳”转型，涉及源头控制、生产过程、末端降碳、科技助力、金融支持、标准计量及产业规模等方面，从我国成品油和化学品供需关系看，“减油增化”势在必行。国际能源公司对炼油和化工业务进行优化整合，重点投资和合作天然气、新能源等业务。国际化工公司产业链长，产品差异化和优势化明显，已在生态发电、航空、建筑、新能源汽车、电子电器、氢能等领域的材料和技术解决方案占领市场，国内石化企业现已开展了面向“碳中和”的转型尝试，向规模化和一体化、高端化学品、耦合新能源等方向发展。“双碳”背景下，石化企业面临着巨大的机遇和挑战，应以国家和行业政策为纲领指引，分析自身优劣势，结合当地资源，调整化工产品结构，发展与当地市场衔接的化学品产业链，并注重跨行业合作推动自身转型。关键词 石化企业；转型；双碳
Revitalization of a mature oil-bearing basin by a paradigm shift in the exploration concept.A case history of Bohai Bay,Offshore ChinaZaisheng Gong a ,Weilin Zhu a ,Percy Pei-Hsin Chen b ,*a China National Offshore Oil Corporation,P.O.Box 4705,Beijing,China bPetrosino Consultants,57Herringbone #201,Irvine,CA 92620,USAa r t i c l e i n f oArticle history:Received 29July 2009Received in revised form 11November 2009Accepted 16November 2009Available online 21December 2009Keywords:BohaiExploration concept Dynamic balance Earthquake energy Migrationa b s t r a c tThe Bozhong Depression in Bohai Bay was previously ranked as an unfavorable exploration region due to concerns about reservoir,trapping integrity and top seal risks.In the mid 1900s,a few explorationists began to view the petroleum accumulation conditions more positively.They argued that rapid Neogene subsidence could have generated a new suite of source potential and that recent continued fault movements may have provided the needed conduits for upward hydrocarbon migration.They predicted the existence of lacustrine facies that could supply the needed lateral and top seals for the intensively faulted traps.These radical thoughts were gradually formulated into a new concept for the Neogene targets.This paradigm shift in exploration concepts has,since 1995,led to the discovery of nine (9)major oil fields with a combined in-place reserves more than double those discovered in the previous thirty (30)years.Some of these Neogene reservoirs appear to be at a dynamic balance between hydrocarbon escape and charge.It is speculated that the required driving energy for the charge may have come from earthquake activities.Ó2009Elsevier Ltd.All rights reserved.1.IntroductionOffshore Bohai petroleum exploration began in 1965and explorationists in the following 30years adapted the same strategy as their onshore colleagues pursuing Paleogene and buried hill targets.The drilling campaign during this period was,however,not met with parallel success as onshore and resulted in finding only one major and a few medium to small size oil fields.As more data and new technology became available,risks associated with reservoir,migration,and trap integrity for the Neogene targets were considerably reduced and thus allowed explorationists to formulate a new exploration concept.Between 1995and 2000,nine (9)major oil fields were discovered with a total reserve of 1700MM tons,which is more than double the reserve discovered during the previous 30years.The more recent discovery of the Nanpu oil fields in 2004has added to this in-place reserve another 445MM tons.This paper discusses the paradigm shift in exploration concepts,which has led to the revitalization of a mature oil-bearing basin.Detailed presentations of individual field’s trapping mechanism,structural development and petroleum system are not intended for this paper.2.Tectonic settingsBozhong is one of the six oil-bearing Tertiary depressions in the North China Basin (Fig.1).In the Bohai Bay exist the Bozhong Depression and the extensions of the other depressions.These offshore depressions are further separated into isolated sags by massifs and uplifts (Fig.2).Petroleum systems in these depressions consist of Paleogene lacustrine source rocks,which charged reser-voirs including sub-cropping Pre-Cambrian migmatites,Paleozoic carbonates,Mesozoic volcanics and volcaniclastics,and Tertiary bioclastics and clastics.The stratigraphy in the Bozhong Depression consists of clastic sediments of non-marine facies with lacustrine sediments occurring mainly in the Paleogene (Fig.3).North China Basin is a rift basin initiated by right-lateral transtensional tectonic forces near the end of the Mesozoic (Apperson et al.,1998).The rifting was interrupted by three episodes of regional uplift,each of which resulted in a regional unconformity (Fig.3).The first episode is represented by the Kongdian Formation,consisting of alluvio-fluvio-delta sediments.The second episode occurred in the Eocene,during which source rocks of lacustrine facies,known as the Shahejie-III and II Members,were deposited in isolated sags with local thickness exceeding 2000m.The third episode is marked by a unified basin with its depo-center located in the Bozhong area.This episode is represented by*Corresponding author.Tel.:þ19493358077(cell);fax:þ19493876887.E-mail address:percychen@ (P.P.-H.Chen).Contents lists available at ScienceDirectMarine and Petroleum Geologyjournal homepage:www.elsevier.com/locate/marpetgeo0264-8172/$–see front matter Ó2009Elsevier Ltd.All rights reserved.doi:10.1016/j.marpetgeo.2009.11.010Marine and Petroleum Geology 27(2010)1011–1027a period of basin-wide Oligocene deposition,1000–4000m thick,with lacustrine facies in the depocenter and mixed fluvial and lacustrine facies in the periphery.The stage of basin thermal subsidence commenced after the regional uplift at the Oligocene/Miocene boundary,during which alluvial,fluvial and flood plain deposition predominated in most parts of the basin.Bozhong,however,remained as the subsidence center and received shallow lacustrine sediments.While most of the North China Basin entered into a period of tectonic quiescence since the Miocene,the Bozhong Depression remained relatively active throughout the Neogene.This was especially the case during the Pliocene,when the depression experienced another episode of structural disturbance along the Tanlu Fault (Gong,2004).The fault is a transtensional fault extending over 400km offshore from Liaodong Bay in the north to the Liaozhou Bay in the south.This tectonic disturbance has been commonly referred to as the Neotectonism in China and has been proven to have significant impacts on the petroleum accumulations in the depression.A number of oil/gas fields have been found along the fault,suggesting effective lateral fault seals still exist in places (Fig.4).3.Exploration historyThe first discovery well in the Bozhong Depression was drilled in1965and found oil in the Oligocene sandstones.Following this,the offshore exploration history is characterized by a period of exploration by CNOOC from1965to 1980and a joint venture period between 1981and 1994.During the former period,a heavy crude pool,known as the Suizhong 36-2oilfield (Fig.2),was found in Oligocene deltaic sandstones draped over a shallow basement high.Explorationists of this period,with limited offshore data and capital investment,essentially followed the strategy used by their onshore ck of parallel successes similar to the onshore,where multiple giant fields were discovered,puzzled some explorationists who then began searching for alternative exploration models (Wang and Wang,2000).During the joint venture stage,over 20contracts were awarded to foreign companies.The pre-Neogene reservoirs still remained as the primarily targets,but only two medium-sized oilfields were brought on production in the concession areas.Thirty years after the first well was drilled,explorationists began to comprehend the unique character of the Bozhong Depression with regard tobasinFig.1.Tectonic map of the North China Basin.The basin contains six major depressions separated by pre-Tertiary uplifts and massifs formed during Tertiary rifting.Z.Gong et al./Marine and Petroleum Geology 27(2010)1011–10271012development and shifted their focus to the Neogene structures around the depression.In 1995,the first break through was made over the Shijiutuo massif with the discovery of Neogene reservoirs in the QDN32-6oilfield (Fig.2).Prior to this discovery,a number of wells had been drilled on the massifs to test the buried hill play but found no pre-Tertiary reservoirs.From 1996to 2000,a succession of nine major oilfields was discovered (Table 1),of which seven were estimated with in-place reserves greater than 600MM tons.The total reserves added in this short 5years period are more than double the reserves found in the previous 30years.The recent discovery of Nanpu oil fields in 2004has added another 445MM tons to the in-place reserves.4.Development of exploration conceptsNew technology in data collection,processing and interpreta-tion have contributed to the increasing understanding of the petroleum system in the Bozhong Depression,but the break through in the exploration concept played the most important role in the recent success.The new concept has been progressively developed and formulated through the post-mortem analysis of Pre-Neogene target drillings.Failure to match the onshore success,where multiple pools were often vertically stacked and horizontally distributed in zones across sub-basins (sags),dictated explorationists in the Bohai Petroleum Administrative Bureau to re-examine seismic records and well data and to re-interpret depositional history and basin structural development,in particular the influence of Tanlu Fault Zone on potential structural closures.Because of the deep burial of Paleogene targets,continued and recent fault movements and poor crude quality at shallow depths,the Bozhong depression was widely believed to be an unfavorable exploration region (Gong and Wang,2000).Furthermore,early drilling results around the periphery of the depression clearly indicated the absence of regional top seals.In the depression,the Miocene sediments reach up to 7000m in thickness but were considered as to have poor source potential.Reservoir quality risk associated with the deep buried Paleogene targets below thick Miocene overburden became a critical concern to most reservoir engineers.The structural features associated with thewrenchFig.2.Major structural elements and oil/gas fields in the Bohai Bay.All fields,with the exception of JZ9-3and SZ36-2,were discovered after the 1995major change in exploration strategy.Z.Gong et al./Marine and Petroleum Geology 27(2010)1011–10271013movements along the Tanlu Fault were noticed but down played because of the concerns on trapping integrity.In addition,Neogene reservoirs discovered in the depression were mostly unconsoli-dated fluvial sandstones at depths ranging from 1000to 1500m and contained low gravity crude (API 10-20).Evidence of the res-ervoir’s rapid facies changes,low connectivity and productivity could have hardly justified the commerciality of an offshore production facility.These detrimental elements previously considered for petro-leum accumulation were re-evaluated in a positive approach by a few explorationists in the mid 1990s.These explorationists,based on the common association of source rock presence with high rates of subsidence in the onshore depressions,speculated that rapid Neogene subsidence could have generated a new suite of source potential previously ignored and that recent fault movements along the Tanlu Fault could have provided needed conduits for upward hydrocarbon migration into Neogene reservoirs (Zhu and Wang,2000;Gong and Wang,2001;Gong,2004).Sequence stratigraphic studies showed fluvial systems drained toward the depression center,where the predicted lacustrine environments could provide the needed regional top seals (Mi,2001).These radical thoughts were gradually formulated into a new conceptforFig.3.General stratigraphy of the Bozhong Depression showing major tectonic and depositional events and source,reservoir and seal custrine source rocks are concentrated in the Dongying and Shahejie Fms.Discovered reservoirs range in age from pre-Tertiary metamorphics (buried hills)to Pliocene clastics.Shajejie Formation is divided into four members,generally referred as Sha-I,II,III and IV in descending order.Z.Gong et al./Marine and Petroleum Geology 27(2010)1011–10271014exploration fairway.The commercial viability of this fairway was greatly enhanced by the success of production test of heavy crude oil from the Neogene reservoirs in the Suizhong 36-2field in the Liaodong Bay (Fig.2).During1995–1998,this new exploration concept was put to test and led to the CNOOC’s discovery of QHD32-6,NB35-2and BZ25-1fields.This sequence of success resulted in a shift of exploration focus toward the structural high areas surrounding the Bozhong Depression.A number of closures and leads were subsequently mapped by CNOOC,but most of them were located in the joint venture OOC,at that time,only held the Shijiutuo Massif (Fig.3)for their exploration.The foreign opera-tors were presented with this new exploration concept at many meetings,but they still insisted on pursuing the traditional pre-Neogene plays.During this period,a total of 18wells were drilled in the concession areas to test the pre-Neogene structures but with no commercial success.Only at the time of planning their last obligatory wells,did operators reluctantly accept this new exploration concept and started drilling the Neogene structures.Thus,from 1999to 2000,Neogene reservoirs were successively tested in the PL19-3,PL25-6,CDF11-1,CDF12-1,PL9-1,LD27-2and LD32-2major oil fields.The development of this new exploration concept has undergone a process from an incipient out-of-the-box geological model with little supporting data,through re-evaluating tectonic activity to infer variation in basin evolution for predicting facies distribution,and finally to collect new data to validate this model.During the process,the impact of Neogene tectonics on source rock deposition and maturation,migration,trap formation and seal rock distribution has been progressively better understood by explorationists,whoinFig.4.Distribution of Neogene faults in the Tanlu Fault Zone.The occurrence of petroleum accumulations in this intensely faulted area suggests that some of these faults are capable of providing efficient lateral seals.Z.Gong et al./Marine and Petroleum Geology 27(2010)1011–10271015turn,have successfully tested various plays where they could opti-mize these elements of petroleum accumulation.5.Influence of Neotectonism on petroleum accumulation The tectonostratigraphy of the Greater North China Basin can be generalized as a Paleogene syn-rift sequence and a Neogene post-rift sequence (Zhang,2003).Vertical differential movements duringthe post-rift period are far less intensive than the pre-rift period and are usually restricted to the reactivation of boundary faults.Tectonic movements in the Bozhong Depression area are,however,local exceptions;they appear to have increased in activity with time,in particular,during the Pliocene and Quaternary.The impact of this Neotectonism on petroleum accumulation is most evident in the creation of juxtaposition of source,reservoir,and seal rocks,as well as favorable elements for migration,maturation andtrapping.Table 1Fig.5.Geologic cross-sections show the stratigraphic intervals of major reservoir and source rocks in different depressions.These intervals decrease in age toward the Bozhong Depression from the Jizhong Depression in the west and the Jiyang Depression in thesouth.Table 2Z.Gong et al./Marine and Petroleum Geology 27(2010)1011–102710165.1.Migration of subsidence centerEvolution of the Greater North China Basin shows an overall seaward decrease in age of basin subsidence and tectonic activi-ties.This seaward shift is mirrored by a parallel trend of petro-leum generation,migration and trapping.Fig.5shows two geological cross-sections across the rift grabens,one from the west to the Bozhong Depression and the other from the south.It is evident that Paleogene sediments in depressions near the mountain ranges and massifs thin seaward and are replaced by the thickening Neogene sections in the Bozhong Depression.The Paleogene subsidence rates are2–3times higher in the onshore depressions than those in the Bozhong Depression(Table2).But the reverse is true for the Neogene subsidence rates;they are four times higher in the Bozhong Depression than those in the onshore depressions.5.2.Temporal and spatial variation of reservoir and source rocksRates of subsidence appear to play a major role in source rock deposition and maturation.Proven source rocks in the North China Basin are all of lacustrine facies,which tends to maximize its distribution and thickness in areas with maximum rates of subsi-dence.Hence a geographic shift in a depocenter through time is often reflected by a stratigraphic shift of source intervals at different geographic locations(Fig.5).It is speculated that during the basin development,the deepening of these sags might have been accompanied by widening as well.In this circumstance, a relative balance between sedimentary supply and accommoda-tion space might have been maintained such that facies boundaries remained stationary.This would permit thickening of both distal and proximal facies during subsidence.It is interesting to note that reservoir development also appears to have followed the shift of subsidence centers in time and space (Table3).The Neogene depocenter of the North China Basin is located in the Bozhong Depression,where the Neogene reservoirs contain over70%of the total in-place reserves of the depression.In contrast,the Paleogene depocenters are located in the onshore depressions,where reserves are predominantly contained in the Paleogene or older reservoirs.Such correlation of source and reservoir development with the spatial and temporal development of depocenters clearly indicates limited vertical and lateral petro-leum migration in these rift grabens.5.3.Juxtaposition of seal and reservoir rocksThermal subsidence during the Neogene allowed the coales-cence of Paleogene depressions to form a unified North China Basin with its depocenter in the Bozhong Depression.During this period,thick proximal facies dominated around the basin periphery and graded into distal facies toward the basin center, where lacustrine deposits were surrounded by meandering and distributaryfluvial sediments(Fig.6).This facies transition iswell Table3Fig.6.Depositional facies map of the Upper Guantao Formation.The map is interpreted based on well data and sequence stratigraphy studies.Distal facies is located in the central part of the Bozhong Depression,where top seal efficiency is enhanced by the decrease in sand content:contours in sand percentage.Z.Gong et al./Marine and Petroleum Geology27(2010)1011–10271017Fig.7.Well cross-section showing an eastward increase in seal rock component in the Neogene stratigraphic columns.Index map depicts the location of the cross-section in relation withmassifs.Fig.8.Isopach map of the Oligocene Dongying Formation in the Bohai Bay.The thickest sections (>4000m)are found in the Bozhong Depression,where the formation becomes matured under the thick overburdens.Z.Gong et al./Marine and Petroleum Geology 27(2010)1011–10271018reflected by the decrease in sand/shale ratios in the Guantao Formation toward the Bozhong Depression (Fig.7).This reduction in sand/shale ratios along with thickening of clay intervals enhances the top seal efficiency and optimizes the reservoir and seal combination.In the Bozhong Depression,sand/shale ratios in the proven reservoir intervals are found not to exceed 40%in the Neogene reservoirs.For example,the reservoir intervals in the Minghuazhen Formation in the QHD32-6field are composed of 30–40%of sand-stones at depths of 910–1550m with porosity 21–35%.The reser-voir intervals in the Guantao Formation in the PL19-3field contain 40%of sandstones at depths 1000–1400m with porosity ranging 20–34%.Insufficient mudstone contents in top seals are believed to be the primary cause of failure for the Neogene traps in the basin periphery.5.4.Generation of matured source rocks in the Late Oligocene Major source intervals in the Greater North China Basin exist in the syn-rift Paleocene and Eocene sections.Good to excellent Types I and II source rocks are present in the organic-rich,liquid-prone,lacustrine mudstones in the Shahejie-III Member.In the Bozhong Depression,this syn-rift member contains relatively thin mudstone intervals,and the major source for the oil in the Neogene reservoirs is believed to have primarily come from the post-rift Dongying Formation.This formation contains thick lacustrine sediments and is thermally mature under the thickoverburden of Neogene sediments exceeding 4000m in thick-ness.The rapid subsidence in the Neogene could have also developed over-pressure and low thermal gradients,which in turn could have delayed the hydrocarbon expulsion from the syn-rift source rocks and later charged the Neogene reservoirs along with the expulsion from the post-rift source rocks (Hao et al.,2004).The source potential of the Dongying Formation had long been a subject of speculation (Huang and Li,2002)and was later confirmed by the PL14-3-1well,which showed TOC values up to 5%in the lower member of the formation and a 0.6Ro at 3000m.The formation has a wide areal distribution exceeding 8000km 2with thicknesses up to 4000m (Fig.8).Oil and source correlations also support the expulsion from the Dongying mudstones.Biomarker analysis of crude oil and source rock samples collected from the Shijiutuo area demonstrates sequential migration of oil generated from both the Shajejie and the Dongying Formations (Hao et al.,2009).Gas chromatography and mass spectrometry (GC–MS)analyses of steranes and terpanes indicate a close affinity between oil samples from the depression and mudstones collected from the PL14-3-1well.Fluid inclusion and burial history analyses have been used to deduct migration history.Typical homogenization temperatures often show distinct groupings.Samples from the BZ29-1-1and QHD27-2-1wells,for examples,display two modes,suggesting two episodes of charging (Fig.9).Timing of these episodes is estimated by the samples reaching their homogenization temperatures at depths in the wellBZ 29-1-1Sample Depth 2274 m Homogenization Temperature o C Two groups of T H 80-130, 150-19090110130150170190210N u m b e r o f S a m p l e s864290110130150170190210642N u m b e r o f S a m p l e sQHD27-2-1Sample Depth 2221 mTwo groups of T H 80-150, 160-180Homogenization Temperature o CFig.9.Histograms of homogenization temperature obtained from the fluid inclusion study of the BZ29-1-1and QHD27-2-1well samples show two episodes of petroleum charge as indicated by the grouping of homogenization temperatures.Ma 504030201030o50o70o90o110o100030002000Sample DepthM i n g h u a z h e nB a s e m e n tGuantao Dongying NeogenePaleogene Depth MF or ma t i o nEstimated Peak Charge: 4 Ma to Present100030o50o70o90o50403010202000M i n g h u a z h e nBasementG u a n t a oDongying Neogene Depth MF or ma t i o nM a Paleogene Sample DepthEstimated Peak Charge: QuaternaryQQBZ29-1-1QHD27-2-1Fig.10.Burial and thermal history models constructed for the BZ29-1-1and QHD27-2-1wells.The dotted lines represent the time-depth plots for the fluid inclusion samples in Fig.9.The migration timing is indicated by the samples reaching their homogenization temperatures at depth;4Ma to present for the BZ29-1-1and Quaternary for the QDN27-2-1samples respectively.Z.Gong et al./Marine and Petroleum Geology 27(2010)1011–10271019burial history (Fig.10).Our regional fluid inclusion and burial history studies show most migrations in the Bozhong Depression took place in two episodes with peak charges occurring in the Pliocene and Quaternary (Table 4and Fig.11).5.5.Formation of structural trapsOffshore Bohai is characterized by intensive Neotectonic activ-ities since the Miocene,in particular along the Tanlu Fault Zone.Anumber of anticlines and faulted anticlines have been mapped as Neogene trapping structures (Wang and Wang,2000;Zhu and Wang,2000;Li et al.,2001;Li and Huang,2001;Huang and Li,2002).Shear movements along the Tanlu Fault Zone have deformed pre-existing drapes and rollover closures and created various types of wrench-related structures,including flower structures,small pull-apart basins,horst and graben structures,and en-echelon folds (Fig.12).The PL19-3structure is a wrench-related anticline (O’Reilly et al.,2000;Patton et al.,2000),initiated in the Late Miocene by basin inversion (Fig.13).The BZ25-1S feature is a rollover structure deformed by later faulting (Fig.14).A number of half-anticlines and faulted noses associated with the Tanlu Fault have been interpreted as transtensional structures (Figs.15and 16)and transpressional folds (Fig.17).Rollover by differential subsidence between fault blocks is seen in the PL14-3structure (Fig.18).Fault closures,BZ34for example (Fig.19),are common in the Tanlu shear zone and they are laterally trapped by branching,en-echelon or right-stepping strike-slip faults.5.6.Providing late migration pathwaysTertiary faults in the North China Basin play an important role in providing migration pathways.Paleogene faults occur basin wide and are mostly syn-sedimentary with over a thousand meters of throw and several kilometers of extension.They often offset pre-Tertiary basement and provide the principal vertical migration pathways for the oil generated in the Eocene and Oligocene source rocks (Gong,2004).Neogene fault movements,on the other hand,appear to have been more active offshore than onshore.Faults in the offshore area show a distinct increase in number and in density but decrease in dimension through time.Some of these faults are associated with the reactivation of old faults and others are inde-pendently developed by the shear stress system along the Tanlu Fault Zone (Zhu and Wang,2000;Hsiao et al.,2004).Shear related faults display a distinctive change in strike along the Tanlu Fault,trending NE in the Liaodong Bay and EW in Bozhong and Laizhou Bay areas (Fig.12).Table 4Results of fluid inclusion and isotope analyses of Bozhong Depression core samples showing predominant two episodes of charging occurring in Pliocene–QuaternaryFig.11.Fluid inclusion and burial history studies show most petroleum migrations in Bozhong Depression took place in two episodes with peak charges occurring in Pliocene and Quaternary times.One episode of migration only occurred through the basement rocks at BZ28-1-2and BZ27-4-2wells (see Table 4).Z.Gong et al./Marine and Petroleum Geology 27(2010)1011–102710205.7.Redistribution of old oilsNeogene fault activities have significantly impacted petroleum accumulations in the offshore area.These faults could either re-distribute old oils or provide new migration pathways from the Paleogene source rocks to Neogene reservoirs (Zhang et al.,2004).Redistribution takes place where these faults breach the Paleogene reservoirs,and oils could re-migrate upward into theyoungerFig.12.Fault distribution maps showing various closure types in association with:a)wrench faults in the northern Liaodong Bay;b)en-echelon faults in the southern Liaodong Bay;C)E–W trending faults in the Laizhou Bay;d)‘‘negative flower’’structure in the BozhongDepression.Fig.13.Seismic cross-section intersecting the PL19-3field.The section is flatted on the 24.6Ma horizon to show the inverted anticlinal structure at the well.reservoirs.It has been noted that this re-migrated oil tends to be biodegraded heavy oil.For example,geochemical data of oil samples from the BZ25-1field indicate that the heavy oil in the Minghuazhen and Guantao Formations was re-migrated from the Shahejie-III reservoir (Fig.20).Alternatively if these faults intersect older,deeply buried faults,oils could migrate upward from the matured Paleo-gene source rocks into the Neogene reservoirs (Fig.21).Oil trapped by this way tends to have properties which vary with depth;the shallower the reservoir the heavier the crude (Bao et al.,2002).A combination of the two possible methods of charge is seen intheFig.14.Seismic cross-section showing the BZ25-1S rollover structure deformed by later faulting;depth inmilliseconds.Fig.15.Seismic cross-section showing the JX1-1field as a half anticlinal structure against a trapping fault.The structure is believed to be induced by transtensional stress;depth in milliseconds.。
文章编号：1000 − 7393(2022)04 − 0468 − 07 DOI: 10.13639/j.odpt.2022.04.010海上气顶油藏屏障注水立体井网的构建岳宝林中海石油(中国)有限公司天津分公司引用格式：岳宝林. 海上气顶油藏屏障注水立体井网的构建［J ］. 石油钻采工艺，2022，44（4）：468-474.摘要：海上气顶窄油环油藏平行于流体界面，部署水平井取得了较好的避气控水效果，但开发中后期依旧面临气窜加剧、液量下降、开发方式亟需调整的难题。
应用油藏数值模拟的方法，针对试验井组开展不同注水井型、水平井不同布井方向、水平井不同布井位置方案的对比，完成屏障注水立体井网的构建试验。
试验结果表明，偏离中轴线靠近Ⅰ期油井40 m 的水平井平行立体注采井网开发效果最好，相较于天然能量开发，可提高采收率7.8个百分点。
依据井网优化结果开展三维物模实验，最终采收率达到43.1%，与天然能量开发模拟采收率34.2%相比，采收率提高8.9个百分点。
物模实验确定了屏障注水的有效性，并量化了屏障注水的开发效果。
下一步计划以井组试验、逐步推广的方式实现油田开发方式调整，可为相似油田屏障注水方案研究提供依据。
关键词：气顶油藏；窄油环；物模实验；气窜；屏障注水中图分类号：TE53 文献标识码： AConstruction of 3D well pattern for barrier water injection in offshore reservoirs with gas capYUE BaolinCNOOC (China ) Tianjin Company , Tianjin 300459, ChinaCitation: YUE Baolin. Construction of 3D well pattern for barrier water injection in offshore reservoirs with gas cap ［J ］. Oil Drilling & Production Technology, 2022, 44(4): 468-474.Abstract: The offshore reservoirs with gas cap and narrow oil ring are parallel to the fluid interface, and to deploy horizontal well in these reservoirs can achieve good effects in avoiding gas and controlling water, however, However, in the middle and late development stages, these reservoirs still face the difficulties in intensified gas channeling, decreased liquid volume, and urgent adjustment of development methods. By using the method of reservoir numerical simulation, for the testing well group, the comparison of different schemes referring different water injection well types, different horizontal well layout directions, and different horizontal well layout locations was performed, and the construction test of the 3D well pattern for barrier water injection was completed. The testing results show that the development effect of the parallel 3D injection-production well pattern with horizontal wells deviated from central axis and 40 m away from the phase I wells was the best, and the recovery rate was increased by 7.8 percent compared with natural energy development. According to the results of well pattern optimization, 3D physical simulation experiment was carried out, with an ultimate recovery rate of 43.1%, which was 8.9 percent higher than the recovery rate of 34.2% simulated by natural energy development. The physical simulation experiments confirmed the effectiveness of the barrier water injection and quantified the development effect of the barrier water injection. In the next step, it is planned to adjust the development mode in a pattern of well group test and gradual promotion, trying to provide a basis for the studying barrier water injection schemes in similar oilfields.Key words: gas cap reservoir; narrow oil ring; physical simulation experiment; gas channeling; barrier water injection基金项目: 国家科技重大专项“渤海油田加密调整及提高采收率油藏工程技术示范”(编号：2016ZX05058001)。
