Accumulation process simulation and an accumulation model of a fault-adjusted tight sandstone gas reservoir
JIANG Fujie, SHAO Xinhe, LI Lintao , PANG Xiongqi, LI Min, CHEN Xiaozhi, LI Longlong, ZHENG Dingye, HUYAN Yuying
1 State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum-Beijing, Beijing 102249, China 2 College of Geosciences, China University of Petroleum-Beijing, Beijing 102249, China
An apparent breakthrough has been made in tight gas exploration in the edge of Ordos Basin, although tight gas exploration started late. The typical example of tight gas at the edge of the basin is the Upper Paleozoic tight gas in the Linxing
area on the northeast edge of Ordos Basin. However, compared with the interior of the basin, the geological conditions at the edge of the basin are complex, and the reservoir-forming processes and the mechanism of tight gas reservoir adjustment and transformation by faults needs to be systematically revealed. Based on the analysis of tight gas reservoir distribution characteristics, reservoir fluid inclusion characteristics, and basin burial-thermal evolution history simulation in the Linxing area, the reservoir-forming process of fault-adjusted tight sandstone gas at the edge of the basin is now understood, and the reservoir-forming model is clarified. The tight gas reservoirs show differential distribution characteristics in three sets of reservoir-forming combinations. The number of in-source reservoir-forming combinations is the least, the number of near-source reservoir-forming combinations is in the middle, and the number of far-source reservoir-forming combinations is the most. The thickness of nearsource gas reservoirs is the smallest, the thickness of inner source gas reservoirs is the middle, and the thickness of far source gas reservoirs is the largest. Fluid inclusions mainly occur in microcracks in quartz grains, and a small amount occurs in calcite cement and quartz overgrowths. The homogenization temperature of fluid inclusions ranges from 81.7 ℃ to 180 ℃, showing the influence of the Zijinshan magma intrusion on the thermal evolution of source rocks. There are two stages of natural gas charging and accumulation in the study area. In the early stage of gas accumulation, faults and fractures were not developed. The natural gas was mainly charged into the in-source reservoirs, supplemented by the near-source reservoirs. In the middle and late stages of hydrocarbon accumulation, a large number of faults and fractures were generated with the intrusion of the Zijinshan magma. Natural gas was preferentially charged into the near-source and far-source reservoirs along the faults and fractures caused by the intrusion of the magma, and the contribution to the in-source reservoirs was relatively tiny. Generally speaking, the tight gas charging at the basin edge is obviously controlled by faults and fractures, with faults playing the “gas pump.” To explore fault-adjusted tight sandstone gas reservoirs, we should attach great importance to studying faults and fractures.
JIANG Fujie, SHAO Xinhe, LI Lintao, PANG Xiongqi, LI Min, CHEN Xiaozhi, LI Longlong, ZHENG Dingye, HUYAN Yuying. Accumulation process simulation and an accumulation model of a fault-adjusted tight sandstone gas reservoir. Petroleum Science Bulletin, 2021, 04: 539-552. doi: 10.3969/j.issn.2096-1693.2021.04.037
