煤系烃源岩油气生成、排出与滞留特征

Characteristics of oil and gas generation, expelling and retention of coaly source rock

杨恒 龚文平 郑伦举

YANG Heng GONG Wenping ZHENG Lunju

长江大学, 武汉 430100 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

Yangtze University, Wuhan, Hubei 430100, China Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China

针对煤系地层烃源岩的油气生成、排出与滞留能力的有效性问题，选取不同沉积环境、不同时代煤岩及其夹层中的碳质泥岩和泥岩，开展了在成岩作用下的高温高压半开放—半封闭体系模拟实验，建立了相应的演化模式。结果表明，不同沉积环境下，Ⅱ2型煤系烃源岩在生油窗内具有一定的排油能力，也具备较强的烃气生成能力，既可以作为油源岩，也是高效气源岩；而Ⅲ型煤系烃源岩在生油窗内主要以滞留油为主，基本不具备排油能力，主要以排出烃气为主，仅能作为气源岩。生烃转化率主要受控于有机质类型，排烃能力还受控于岩性与丰度，按单位质量岩石而论，煤岩远高于其夹层中的碳质泥岩与泥岩。煤岩在全演化阶段，无论是低阶煤还是高阶煤均具有较强的生成烃气能力和较高的滞留油气能力，都具有煤层气开发潜力。

To understand the effectiveness of hydrocarbon generation, expelling and retention capacities of coaly source rocks, carbonaceous mudstones and mudstones in coal layers and interlayers of different sedimentary environments and ages were selected to carry out the simulation experiments with a semi-open system operated at high tempera-ture and high pressure, and a corresponding model of evolution was established. With different depositional environments, the type Ⅱ2 coaly source rocks expelled oil in the oil generation window with gas generated. Therefore, they worked as source rocks for both of oil and gas. However, for the coaly source rocks of type Ⅲ kerogen, the generated oil was mainly retained during the oil generation window and basically did not expel. As a result, this type of source rock was regarded as source rocks of gas only. The conversion rate of hydrocarbon generation was mainly controlled by the type of organic matter, while the ability to expel hydrocarbons was controlled by lithology and organic matter abundance. For each unit mass of rock, coal rocks has much higher conversion rates than the carbonaceous mudstones and mudstones in their interlayers. In the full evolution stage of coal rock, both low-rank and high-rank coals had strong ability for hydrocarbon gas generation and oil-and-gas retention, which showed a good potential for coal bearing methane development.

中国石化基础前瞻性研究项目“烃源岩演化机理研究” JC-2020-kt001-12;国家自然科学基金企业创新发展联合基金 U19B6003

https://doi.org/10.11781/sysydz202103498