Abstract:

According to a comprehensive analysis of available new data including geolo-gical,geophysical,drilling,satellite images and various evidances of neotec-tonic movement in the Bohai Bay Basin and the adjacent areas,it is found thatthis region was controlled by NW-SE trend compressive stress field during themiddle and late stages of the Mesozoic,thus resulted the reactivation of theplatform,developed a series of NE trend compressed fractures and folds inechelon arrangement,the outcrops of which developed into favourable reservoirrocks with plenty of pores and fractures after long time wheathering and lea-ching.In the Eogene,the basin was controlled by tensile stress field in NW-SE direction,the basement rocks were tilted,leading to a series of rangesand depressions in NNE-NE echelon arrangement filled with rapid depositedsource rocks,as a compensation of the continuously subsided space.In the Neogene,the whole basin depressed in balance due to the clockwise shear move-ment.The range and depression structures then were covered by Neogene sedi-ments,thus formed the buried hills and provided necessary pressure and tem-perature for the generation of oil and gas.The rotational-shearing movement madethe oil and gas to migrate towards the buried hills.The evolution of the stressfield in the area is related to the subduction and compression of the Pacific-Kura Plate and the Indian Ocean Plate towards the Eurasian Plate in different timesand directions.The gushing of the mantle materials,on the other hand,canbe considered as the dynamic source of the tensile-stress field and the thermalsource for the evolution of hydrocarbon.