Fluid abnormal overpressure and its influence on deep clastic reservoir of the Paleogene in Chezhen Sag of Dongying, Shandong Province
Xian Benzhong1,2, Wu Caixi3, She Yuanqi2
1 State Key Laboratory of Petroleum Resource and Prospecting，China University of Petroleum(Beijing），Beijing 102249 2 Faculty of Earth Science，China University of Petroleum(Beijing)，Beijing 102249 3 Research Institute of Exploration and Development, PetroChina Xinjiang Oilfield Company, Karamay 834000，Xinjiang
Abstract：Sandstone and conglomerate reservoir affected by fluid abnormal overpressure in deep layer is one of the focuses in petroleum exploration and reservoir study.Drilling and oil production test data show that abnormal pressure exists widely in the Paleogene Shahejie Formation，and has closely related with oil-bearing and oil productivity of the sandstone and conglomerate reservoir.In this study，formation pressure in different strata and different zones were calculated with equivalent depth method using logging data calibrated by oil production test data.Calculating results show that formation pressure in the lower Submember of Member 3 of Shahejie Formation(Esx3)is the largest，and its residual formation pressure equals 15-30 MPa. According to the statistics on sandstone and conglomerates porosity and their residual formation pressure，the porosity increases 2％ when formation pressure increases 5 MPa.Therefore，the sandstone and conglomerates porosity in Esx3 may be increased by 4％-10％.Integration of microcosmic reservoir characteristics and porosity interpretation of logging data，three factors improving deep sandstone and conglomerate reservoir are listed as follows:(1)fluid abnormal pressure protects primary and secondary pores formed in early periods，(2)overpressure environment produces acidic groundwater into reservoir and forms dissolution pores，(3)fluid abnormal overpressure promotes the formation of microfractures，and improves the seepage capacity.
Xian Benzhong,Wu Caixi,She Yuanqi. Fluid abnormal overpressure and its influence on deep clastic reservoir of the Paleogene in Chezhen Sag of Dongying, Shandong Province[J]. JOPC, 2011, 13(3): 309-316.
