Late Stage Tectonic Inversion And Its Controlled Hydrocarbon Migration And Accumulation In The Songliao Basin, Northeast China

The late stage tectonic inversion of Songliao Basin formed abundant geological response. It made the reverse structure inner the basin, induced the sedimentary & subsiding center of the basin move to the west, and resulted in different uplift-erosion of the basin. The late stage tectonic inversion of Songliao Basin also dominated the evolution of fluid dynamical field, what’s more controlled the migration and collection of petroleum badly.By the analysis of seismic-geological profile and balanced section, we learned the structural evolution of the basin. According to the colligate use of vitrinite reflectivity (Ro), the sonic curve (AC) of mudstones and apatite fission track, systemic depict were made for the late stage uplift-erosion natures of Songliao Basin. The late stage tectonic inversion of Songliao Basin made five reverse structural belts, at the same time, the sedimentary & subsiding center migrated west gradully. The late stage uplift-erosion of the basin had different nature for subareas in the space. East of the basin was uplifted earlier and more, while west later and less. The whole basin became warped differently. The uplift-erosion of the basin had different acts in the time, which include two big acts, four small acts. The first act of quickly uplifting happened form late Cretaceous to the end of Eocene, with the uplift-erosion rate 30～50m/Ma; the first act of slowly uplifting happened form Eocene to the end of Palaeogene, with much smaller erosion rate. The second act of quickly uplifting happened form Oligocene to Miocene, with the erosion rate over 50m/Ma; the second act of slowly uplifting happened form Miocene to nowadays, with erosion rate lower than 10m/Ma. The late stage tectonic movements of Songliao Basin were response to series plate patching up and reforming events in Mesozoic-Cenozoic of east China and near areas. That was especially response to Izanaqi plate subducting-dieing out, Pacific plate subducting down to-patching with Eurasia plate, and Japan Sea opening-closing.Using the distributing of under-compacted mudstones, formation testing (RFT) and drill stem testing (DST) data of wells, we analyzed the features of fluid dynamical field in Songliao Basin. There are four sets of under-compacted mudstones in Songliao Basin, which are Nenjiang formation, Qingshankou formation, the first & second members of Quantou formation and the first & second members of Denglouku formation. The fluid dynamical field of reservoirs could be divided into three systems, which are inside high-abnormal high pressure, middle normal pressure and exterior low-abnormal low pressure system. The interaction between structure and fluid shows as three fluid systems are controlled by late stage tectonic reverse of the Basin; the structural style of depress strata are determined by under-compacted mudstones inner the Basin.With nitric compound oil-gas tracking, autogenetic illite K-Ar dating, oil-gas migrating & assembling history was analyzed for typical reservoirs. The late stage reservoiring of Songliao Basin was fastened during late Cretaceous to early Palaeogene. Daqing Placanticline reservoirs were typical quick filling process of anticlines, which was quick and effective reservoiring. Late stage tectonic movements of Songliao Basin obviously controlled oil-gas migrating & assembling, and it was the main dynamic source of petroleum migrating.