陆相泥页岩源-储协同演化特征分析——以松辽盆地长岭断陷沙河子组为例

Co-evolution characteristics of organic matter and reservoir in continental shale: a case study of Shahezi Formation in Changling Faulted Depression, Songliao Basin

周卓明

ZHOU Zhuoming

中国石化 石油勘探开发研究院 无锡石油地质研究所, 江苏 无锡 214126

Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China

松辽盆地松南断陷群陆相页岩气具有较大的勘探潜力，但对于该区Ⅲ型干酪根富有机质泥页岩的有机地球化学和孔隙特征及演化规律尚不清楚。通过对长岭断陷下白垩统沙河子组Ⅲ型干酪根富有机质泥页岩样品开展生排烃热演化模拟实验和系列储层特征测试分析，发现该泥页岩存在2个关键的热演化节点，等效镜质体反射率（等效Ro）分别是1.5%和2.0%。等效Ro从0.7%至1.5%阶段，为快速生排油阶段，孔隙形态主要为墨水瓶状孔和部分板状孔，有机质逐渐发育少量孔洞，矿物溶蚀孔出现；等效Ro从1.5%至2.0%阶段，为快速生气阶段，有机质分解使得有机孔和矿物间孔洞大量发育，孔径逐渐增大，孔隙主要为板状孔或楔形孔和少部分墨水瓶状孔；等效Ro大于2.0%阶段，孔隙几乎只发育板状孔或楔形孔，孔径进一步增大。Ro大于1.5%为松南断陷群页岩气富集的有利源储耦合阶段。

In the Songnan Faulted Depression Group of the Songliao Basin, continental shale gas has huge exploration potential. However, evolution regularities of both organic geochemistry and pore characteristics in organic shale containing type Ⅲ kerogen in this area are not made clear. According to thermal evolution simulation experiments on hydrocarbon generation and expulsion and the tests and analysis on a series of reservoir characteristics in organic shale samples containing type Ⅲ kerogen from the Lower Cretaceous Shahezi Formation, Changling Faulted Depression, it was found that there were two key nodes of thermal evolution in the shale, namely, equivalent vitrinite reflectance (Ro) of 1.5% and 2.0%, respectively. In the stage of equivalent Ro from 0.7% to 1.5%, it was the stage of fast oil generation and expulsion, in which pore shapes were mainly ink bottle and partially plate, few pores and caverns were developed gradually in organic matters, and mineral dissolution pores occurred. In the stage of equivalent Ro from 1.5% to 2.0%, it was the stage of rapid gas generation, in which a large amount of organic pores and inter-mineral pores were developed with gradually increasing pore size by organic matter decomposition, and the pores were mainly platy or wedge-like and a few pores were ink bottle shaped. In the stage of equivalent Ro higher than 2.0%, only platy or wedge-like pores were developed with further increasing size. The stage with Ro higher than 1.5% is favorable for co-evolution of source rocks and reservoir of shale gas accumulation in the Songnan Faulted Depression Group.

国家自然科学基金项目 42072156

https://doi.org/10.11781/sysydz202302243