Development characteristic of layer-bound polygonal faults and their role in hydrocarbon accumulation in Zhaozhou Oilfield, Songliao Basin
【Abstract】 Through the 3D seismic data interpretation and coherence slices, combined with depositional characteristics of Putaohua reservoir, the development characteristic of layer-bound polygonal faults(PFs) was studied in Zhaozhou oilfield in the south of Sanzhao depression, Songliao Basin. The results show that the layer-bound faults show preferential alignment, that most faults distribution are parallel to the strike of the slope and that aligned faults incline to updip direction of slope. The development period of PFs is coincided with a late Qingshankou stage to early Yaojia stage tilting event, and gravity sliding model is proposed as a possible mechanism for the deformation. Plannar distribution of the faults is controlled by sand body and tectonic faults, PFs mainly concentrate in the area where sandstone-bearing stratum is thin, and individual PFs mostly grow to the footwall of the tectonic faults. Because of the difference in the activity of PFs in geological times, there are differences in the role of faults in hydrocarbon accumulation. The regional stress field of hydrocarbon accumulation period(the end of Mingshui formation) is NW trending compressive stress, NW—NNW faults where oblique slipping occur are pathways for oil migrating vertically from the source rock of the Qing-l member up to Putaohua reservoir, yet layer-bounding EW trending faults are closed under normal compression, so PFs play seal effect in hydrocarbon accumulation. Since the Cenozoic, regional stress field transforms into EW trending compression, PFs oriented parallel or nearly parallel to the maximum horizontal principal stress show high permeability. PFs are expected to be the dominant lateral migration pathways for oil within low-permeability reservoir, and make oil reservoir interconnected.
【Key words】 polygonal faults； layer-bound； gravity sliding； Putaohua reservoir； reservoir-controlling；
- 【文献出处】 中南大学学报(自然科学版) ,Journal of Central South University(Science and Technology) , 编辑部邮箱 ,2015年04期