Lithologic Reservoir Distribution Law And Target Prediction Of Dongpu Depression

Dongpu depression has experienced 20 years' exploration and development. Now it hascome to an exploration period with high maturity. Lithologic reservoirs certainly become thetarget for exploration in Dongpu depression. In this article I have fully studied presentproduction, exploration data and previous achievements of Dongpu depression. Based ondrilling, logging, seismic and experimental data, combining with theory and method ofsequence stratigraphy, this paper carried out a research aiming at sequence III gerust andsedimentary systems. After studying advanced sequence gerust and sedimentary systems, thepaper has also studied lithologic reservoir, grasped its distribution law, built the reservoirformation model, indicated its exploration aspect and made prediction for lithologic traps ininterested areas.11 III sequences exist in interval S3 by classification in Dongpu depression. The middlearea is well developed, while south and north areas only developed perch system andlacustrine approaching system. East of Dongpu depression mainly developed fan deltaicdeposit and west braid river deltaic deposit. Long axis of south and north mainly developedperch deltaic deposit while the middle mainly developed delta and lacustrine fan deposit andso on.Lithologic reservoir types in Dongpu depression: sandstone updipping pinchingreservoir, lenticular reservoir, sandstone (conglomerate) fan body reservoir andstructural-lithologic reservoir. Totally speaking, sandstone (conglomerate) fan body reservoirand structural-lithologic reservoir take the most chances with two characteristics "small" and"deep". Planarly, lithologic reservoir dominantly occurs in middle area where the system isfully developed;Vertically, interval S3 is the main section for lithologic reservoir developing.From the inner of interval S3, it appears that abundant oil and gas exist near level IIIsequence interface, which controls hydrocarbon distribution greatly.The middle is the favorable area for lithologic reservoir development. The area isfavorable and of great importance with fully developed systems, rich sedimentary resourceand abundant oil source. So it is the target for lithologic reservoir exploration especially thering belt and downthrow block of growth fault.From south to north developed 5 fan bodies in Maogang-Qianliyuan member of Lanliaofracture belt: Baimiao, Well Qian7, Well Qian1, Well Qian2 and Maogang. Analysis showsupthrow valley and downthrow fan are well corresponding. These sandstone (conglomerate)fan bodies are closely adjacent to oil generation depression and easily to form lithologicreservoir. Consequently they are considerable targets for exploration.