延川南煤层气田基本特征与成藏关键因素

Basic characteristics and key factors of gas accumulation in Yanchuannan coalbed gas field

郭伟

Guo Wei

中国石化 华东分公司 石油勘探开发研究院, 南京 210011

Petroleum Exploration and Development Institute, SINOPEC East China Branch Company, Nanjing, Jiangsu 210011, China

以延川南煤层气田山西组2号煤层为例,分析了该气田的基本特征。该气田具有构造简单,厚度稳定,低孔、低渗,低压力梯度,生烃潜力大,含气量高,演化程度高等特点。通过研究区断层与含气量、地层水、地层压力梯度的关系,局部构造与割理发育、煤层气产量的关系,以及对煤层气甲烷碳同位素特征的分析,认为:(1)断层对煤层气的富集作用明显,断裂带煤层含气量明显变低;(2)中部断裂带控制了煤层的压力梯度和地层水的分布;(3)煤层气具有混合气(自源和运移来的热成因气)的特征,有一定构造幅度的正向构造,有助于煤层气的富集。

The basic characteristics of the Yanchuannan coalbed gas field were analyzed in a case study of the No.2 coalbed in the Shanxi Formation. The gas field is featured by simple structure, stable thickness, low porosity, low permeability, low pressure gradient, high hydrocarbon potential, high gas content, and high thermal maturity. The relationships between faults and gas content, formation water, formation pressure gradient, the relationships between local structure and cleat development, coalbed gas content, and the characteristics of methane carbon isotopes were studied. Conclusions were drawn as follows. (1) Faults significantly controlled the enrichment of coalbed gas. Coalbed gas content decreased in fracture belts. (2) The central fault belt controlled the pressure gradient of coalbed and the distribution of formation water. (3) The coalbed gas was mixed self-sourced gas and thermogenic gas. Positive structure with certain amplitude is helpful for the enrichment of coalbed gas.

国家科技重大专项(2011ZX05035)06课题资助.

https://doi.org/10.11781/sysydz201503341