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The Dynamics Simulation On Migration And Accumulation Of Oil-gas And Prediction Of Exploration Targets In Nanpu Depression, Bohai Bay Basin, China

Posted on:2010-07-20Degree:MasterType:Thesis
Country:ChinaCandidate:L MaFull Text:PDF
GTID:2120360275976850Subject:Mineral prospecting and exploration
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Nanpu depression,located in the northeastern Huabei platform and southern Yanshan plat formal fold belt,is a small-scale of Tertiary petroferious fault basin in northern Bohai Bay basin. At present,the CNPC have got a great advanced of oil-gas exploration in the north part of the depression,such as Laopu,Laoyemiao,Gaoshangpu and Liuzan area.with the got along in oil exploration,it is still the oil exploration key area for Paleogene Dongyin and Shahejie formation in the south Tanhai area.The oil-gas generation and accumulation is the key factor controlling the pool formation,which is the important elements for researching pool-forming.It is significant to clarify the dynamics and hydrocarbon migration pathway system of oil-gas migration and accumulation for oil exploration in the future.The patten and model of petroleum accumulation are concluded in this study.Base on the data and results exist,the author,considering the evolution of structure and the information of sesmic,geochemistry and DST,analyses the direction of oil and gas migration and diffusion and studies the evolution of sedimentary system,ability of sand body conduction,the activity of faults,the characteristics of seal and the predominant pathway of hydrocarbon by 1D single well simulation and 2D profile and temperature field together with fluid potential stimulation.The result of 1D single well stimultaion shows the 4th and 5th sub-member(Es34,ES35) of Shahejie Formation(Fm) in the lower part of Nanpu depression generate hydrocarbon at 20 Ma, and become mature~overmature at present;the upper part,in the other hand,1st member of Shahejie Fm(Es1) and 3rd member of Dongyin Fm(Ed3) generate hydrocarbon at 10 Ma,and now it gets into the major source period.The petroleum preferred to entering the Es3 at 18 Ma(period of Guantao Fm) and 12~8 Ma(period of Minghuazhen Fm),versus Es1 and Ed at 13~11 Ma(early period of Minghuazhen Fm) and 6~7 Ma(late period of Minghuazhen Fm).However,the petroleum infill injection of Ng(Guantao Fm) is relatively late(2.5 Ma to now).The result of 2D profile stimulation tells us the isothermal line and structural contour of the study area are commonly parallel result from the area is not effected by abnormally thermal fluid and stucture much since paleogene.The characteristic of evolution of the basin abnormally pressure is fluctuant.There two abnormal pressure zones in Es3,Es1 and Ed3 at 18 Ma(middle period of Guantao Fm) and,at that time,the overpressure center was exactly the center of hydrocarbon kitchen.However,the two zones mentioned above become one excessive pressure zone up to now result in well correlation between fluid potential and pressure field and gentle oil potential isoline whose high value area accord with the center of hydrocarbon kitchen and characterize "gravity flow".Conduction system of Nanpu depression mainly consists of lateral conducting of skeleton sand bodies and vertical conducting of faults,however,without conduction of unconformity.The research shows the skeleton sand bodies,lateral sand conduction formation of Ng,Ed1~2 (member of Dongyin formation)and Es31,2,3(submember of Shahejie formation),are the "high way" of the migration of petroleum.Es31,2,3,consisted of widely spread fan-delta plain and fan-delta front,overlaid the source rock of Es34,5,are the main pathway of the first set result from its preferable physical properties.The skeleton sand bodies of Ed1 and Ed2,considered as one set cause their similar and inherited origin and almost the same properties,have more satisying horizontal permeability and lateral connectivity than Es31,2,3 because of their lower overlain lithospheric pressure.The skeleton sand bodies of Ng are the most valuable of all and contribute a large number of reserviors.Petroleum transport along faults from deep to shallow and finaly migrate laterally and accumulate.Mudstone seal of Es2 and Ed2,interbedded among the 3 conductive layers above by chronological order,are perfect barriers and force the oil and gas laterally transporing only in their own formation.Ⅲorder fracture and its allied secondary fracture,spreading along NEE direction,are the main vertical pathway of oil and gas.The complex fracture system prevent the lateral migration of petroleum in Nanpu depression,whereas,theⅢorder fracture distributed in the mature source rock area,such as Beibao No.1 Fault,Gaoliu Fault,Nanpu Fault,Laobao No.1 and 2 Fault etc, communicate the lower part source rock and the trap because of the characteristics of early formating,large displacement and longtime activity.Therefore,theⅢorder fracture and its allied secondary fracture constitute the vertical complex hydrocarbon conduction system which make the deep-buried petroleum transporting uptoward,accumulating,separating,retransporting and reaccumulating.This is the origin of the shallow complex reservior zone distributed along theⅢorder fracture.Considering the excellent source rock,trap and seal condition,the petroleum migration and accumulation are mainly controlled by the consanguinity and sealing characteristic of faults and heterogeneity of reservior.The model of accumulation of oil and gas can be divided into three different patterns accoding to different conductive system.They are:(1)the modle controlled by lateral skeleton sand bodies conduction system;(2) the modle controlled by vertical faults conduction system;and(3) the modle controlled by the combination of the two system above.By comprehensive consideration of petroleum geologic condition,we predict that the anticlinal trap,the fault block- lithologic and the fault screened trap in Nanpu No.2 and 4 structure step-fault zone,together with,the anticlinal and fault block trap in "Y-type" fracture zone can be treated as traget area during exploration and production.
Keywords/Search Tags:dynamic simulation, migration and accumulation of oil-gas, exploration targets, Nanpu depression
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