岩浆侵入作用对不同成熟度烃源岩热演化的影响——以方正断陷和绥滨坳陷为例

Impact of igneous intrusion on the thermal evolution of source rocks with different maturities: a case study of Fangzheng Fault Depression and Suibin Sag in north-eastern China

冯禄 曾花森 王洪伟

FENG Lu ZENG Huasen WANG Hongwei

1. 北京大学 地球与空间科学学院, 北京 100871; 2. 大庆油田有限责任公司 勘探开发研究院, 黑龙江 大庆 163712

1. School of Earth and Space Sciences, Peking University, Beijing 100871, China; 2. Exploration and Development Research Institute, Daqing Oilfield Company Ltd., Daqing, Heilongjiang 163712, China

为研究岩浆侵入体对不同成熟度烃源岩有机质热演化的影响程度和范围，对黑龙江东部方正断陷和绥滨坳陷中的2口探井进行了系统取样与分析，基于岩石地球化学指标，研究了受岩浆侵入影响的烃源岩有机质成熟度及生烃特征在纵向上的变化。结果表明，岩浆侵入体的热烘烤范围与围岩热成熟演化阶段或成岩阶段密切相关。岩浆侵入时烃源岩处于早成岩阶段（未熟—低熟阶段），岩石比热容高、热导率低，岩浆热烘烤范围较小，影响范围平均是侵入体厚度的1倍左右，Ro最高可达2.5%。岩浆侵入时烃源岩处于中成岩晚期—晚成岩阶段（成熟—高成熟阶段），岩石比热容低、热导率高，岩浆热烘烤范围大，影响范围平均是侵入体厚度的2倍左右，Ro最大值约为4.0%。

Two intruded sections, respectively from the Fangzheng Fault Depression and the Suibin Sag in the north-eastern China, were continuously sampled and geochemically analyzed in order to decipher the thermal impact of igneous intrusion on source rocks with different thermal maturities. The changes of organic matter maturity and hydrocarbon generation characteristics of source rocks affected by igneous intrusion were studied according to the geochemical indicators of the rocks. The results showed that the thermal impact of igneous intrusion is distinguishable with sample organic maturity or diagenesis phase at the time of intrusion. When a source rock in its early diagenesis phase with a low organic maturity is intruded by magma, the thermal aureole is on average the thickness of the intrusion body and the maximum enhanced maturity can be up to 2.5% Ro. In contrast, when a source rock in its middle-late diagenesis phase with a high organic maturity is intruded, the thermal aureole is on average twice the thickness of intrusion body and the maximum enhanced organic maturity can be up to 4.0% Ro. It was suggested that in the early diagenesis phase, source rock bears a high specific heat capacity and a low thermal conductivity, and the thermal impact is less; whereas in the middle-late diagenesis phase, source rock bears a low specific heat capacity and a high thermal conductivity, and the thermal impact is greater.

国家重点基础研究发展计划（973计划）“火山岩油气藏分布规律与资源预测”（2009CB219308）资助。

https://doi.org/10.11781/sysydz201805724