川南筇竹寺组页岩储层孔隙连通及油气充注特征

Pore Connectivity and Oil and Gas Filling Characteristics of Shale Reservoirs in the Qiongzhusi Formation, Southern Sichuan

史洪亮 邓明全 周桦 何建华 徐浩

SHIHongliang DENGMingquan ZHOUHua HEJianhua XUHao

中国石化西南油气分公司勘探开发研究院, 四川 成都 610041 油气藏地质及开发工程全国重点实验室·成都理工大学, 四川 成都 610059

Exploration and Development Research Institute, Southwest Petroleum Branch, SINOPEC, Chengdu, Sichuan 610041, China State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu, Sichuan 610059, China

川南筇竹寺组页岩气资源丰富，勘探潜力巨大，但储层孔隙连通性及油气充注特征尚不清晰。基于高压压汞、低温N$_2$吸附和FIB-SEM实验表征研究区筇竹寺组页岩孔隙结构及连通性特征，并结合生烃动力学模拟分析资阳—井研地区的油气充注能力。研究表明：1) 井研地区筇竹寺组富有机质页岩层孔隙连通性较差，孔隙连通率为32.8%，但具有较大的生烃压力，达48.50 MPa，而粉砂质页岩层孔隙连通性好，孔隙连通率为55.7%，生烃压力为31.60 MPa；2) 资阳地区筇竹寺组页岩生烃压力为井研的1.3$\sim$1.9倍，最高达62.80 MPa，流体包裹体测试表现出60.00 MPa的成藏压力，与之相符合；3) 通过油气充注动力学模拟得出，生烃前中期槽内(资阳地区)油气增压明显，最高达56.50 MPa，向斜坡区(井研地区)发生运移；生烃后期页岩埋深增大，储层致密化，充注阻力增加，充注动力无法突破阻力，井研地区为原地有机质裂解供烃。

Qiongzhusi Formation in southern Sichuan is rich in shale gas resources, demonstrating significant exploration potential. However, the characteristics of reservoir pore connectivity and the mechanism of oil and gas injection remain unclear. This article studies the pore structure and connectivity characteristics of the Qiongzhusi Formation shale in the study area based on high-pressure mercury injection, low-temperature N$_2$ adsorption, and FIB-SEM experiments. Additionally, the hydrocarbon injection capacity in the Ziyang-Jingyan Area will be investigated in conjunction with shale hydrocarbon generation kinetics simulation. The research indicates that: 1) the organic rich shale layer in the Qiongzhusi Formation of the Jingyan Area has poor pore connectivity, with a pore connectivity rate of 32.8%. However, it has a large hydrocarbon generation and pressurization scale, with a maximum cumulative overpressure of 48.50 MPa. On the other hand, the silty shale layers have good pore connectivity, with a pore connectivity rate of 55.7%, and a hydrocarbon generation and pressurization of 31.60 MPa; 2) the scale of hydrocarbon generation and boosting in the Qiongzhusi Formation shale in Ziyang Area is 1.3$\sim$1.9 times that of well research, reaching up to 62.80 MPa. Fluid inclusion testing shows a reservoir pressure of 60.00 MPa, which is consistent with this; 3) through the simulation of oil and gas injection dynamics, it was found that the oil and gas in the trough (Ziyang) increased significantly in the early and middle stages of hydrocarbon generation, reaching up to 56.50 MPa, and migrates towards the slope area (Jingyan); in the late stage of hydrocarbon generation, the burial depth of shale increases, the injection resistance increases, and the injection dynamics cannot overcome the resistance. The Jingyan Area is characterized by in-situ organic matter direct cracking for hydrocarbon supply.

10.11885/j.issn.1674 5086.2024.09.13.01