当前位置: X-MOL 学术Gas Sci. Eng. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Utility of inclusions for interpreting reservoir thresholds for tight sandstone gas accumulation in the Longfengshan and Dongling sags, Southeast China
Gas Science and Engineering ( IF 5.285 ) Pub Date : 2019-01-01 , DOI: 10.1016/j.jngse.2018.11.018
Wei Wang , Youlu Jiang , Rudy Swennen , Jing Yuan , Jingdong Liu , Shaomin Zhang

Abstract To better understand the thresholds for hydrocarbon migration in tight sandstone, we studied the gas migration and accumulation processes in the Longfengshan and Dongling sags in the Songliao Basin by determining the ancient pore pressure evolution and gas fractionation. The trapping pressure of coeval aqueous inclusions can be used to identify systematic overpressure trends, which increase during gas charging. Early formation of overpressure and a maximum surplus pressure greater than 6 MPa in reservoirs adjacent to high-quality source rocks (total organic carbon > 1.2%) indicate that the formation of surplus pressure is related to the gas generation capacity. The gas-bearing inclusion distribution and systematic geochemical trends suggest that dynamic gas migration was accompanied by gas fractionation. The results indicate that dissolved gas mainly accumulated in reservoirs with a maximum surplus pressure greater than 6 MPa and that the free gas diffused toward reservoirs with maximum surplus pressures less than 6 MPa. The gas saturations were generally stable and greater than 50% in the high surplus pressure zone. However, in the low surplus pressure zone, the gas saturation was less than 25%, although this value was relatively higher in reservoirs where the maximum surplus pressure was less than 3 MPa. Our results demonstrate that the resistance thresholds for the migration of dissolved gas and free gas differ in tight sandstone reservoirs. The surplus pressures greater than 6 MPa are advantageous for dissolved gas accumulation. An obvious resistance threshold is not observed for free gas migration, although the migration of this gas was relatively inefficient and occurred mainly via diffusion in the direction of decreasing surplus pressure. The results of this study confirm the importance of considering the driving force for natural gas in different phases as a key factor when determining optimal exploration targets.
更新日期:2019-01-01
down
wechat
bug