High-resolution Sequence Stratigraphy And Oil-controlling Models Of Heidimiao Reservoir In Puxi Oil Field

Under the guidance of high-resolution sequence stratigraphy and fine sedimentology, the author made a comprehensive analysis of the materials related to core hole, well logging, seism, etc. of the research area and then through the comparison of the approximation and cycle of isochronous surface with stepwise standard, he/she divided Heidimiao Reservoir(H2) in Puxi oil field into one medium-term base level cycles, five short-term base level cycles and ten super-short-term base level cycles with a unified framework of fine high-resolution sequence stratigraphy in the area being established. In this framework, the author proposed a development model which was featured with thin layer in the west and south while thick layer in the east and north, SSSC1 being the largest recession surface and the general base level being on the decline.Under the fine isochronous framework, the author analyzed provenance and sedimentary facies features and it was found that Heidimiao Reservoir was mainly featured with provenance deposition in the north and northwest, which belonged to river-controlled gentle slope delta sedimentary system with a north-south distribution. Under the deposition condition, lake basin gradually shrank in an upward direction with an inverse cycle sand shale depositional system being formed but there were no distributary plain facies. The underwater distributary channels were pushing toward the lake basin to form dentritic distributary channels. On both sides of the distrubutary channels, large areas of sheet sand were developed. The mouth bars were in dotted distribution and perpendicular to the distal bar which was along the direction of the course of underwater distributary channels. The reservoir stratum mainly comprises distriburaty channel sand, mouth bar sand, distal bar sand and a small amount of blanket sand.In the present research, the author established stratigraphic framework and determined provenance and the spatial distribution of the single sand body of sedimentary microfacies. Then under the guidance of the theories in modern oil-gas geology such as reservoir formation system, etc. and by employing some technologies such as regional accumulation analysis technology, single sand body oil-controlling analysis technology, etc., the author made an analysis of hydrocarbon distribution pattern in Heidimiao Reservoir both in the vertical direction and horizontal direction after combining with the dynamic information of the research area. Besides, the author also analyzed the types and features of the reservoir so as to reveal the local inner structure of single trap and the boundary of hydrocarbon distribution under the control of single sand body, the vertical distribution location of single sand body and the features of hydrocarbon occurrence layers. It was found in the present research that multiple development layers and the spatial association of rapidly changeable sand bodies in the plane with complex local structure were the major cause of complex hydrocarbon distribution in the research area. Besides, the spatial association between local structure and single sand body was also a leading factor affecting inner oil-controlling of the single trap. It is hoped that the present research could provide some guidance for further exploration and development of lithologic reservoir.