郯庐断裂增压带超压特征、成因及其定量评价——以渤海海域辽东湾锦州27段为例

Characteristics, origin and quantitative evaluation of overpressure in strike-slip and compression-shear booster zone of Tan-Lu Fault: A case study in JZ27 section of Liaodong Bay, Bohai Sea

韦阿娟

Wei Ajuan

中海石油(中国)有限公司 天津分公司渤海石油研究院, 天津 塘沽 300452

Exploration and Development Research Institute of CNOOCTianjin Branch, Tianjin 300452, China

郯庐断裂渤海海域锦州27段走滑压扭增压带JZ27-A井区沙三段储层内发育异常高压,压力系数平均值达1.5.其主要特征为:超压顶部有厚层泥岩封隔层、超压发育段颗粒碎裂作用强、发育范围及层位受增压带范围以及走滑压扭强烈发育期影响(仅在JZ27-A井区沙三段储层内发育).其形成机制为:在东三末期到东二早期的郯庐断裂强烈右旋走滑作用下,在走滑压扭增压带JZ27-A井区形成应力强烈集中区,从而形成水平构造挤压应力,同时由于上覆厚层泥岩的存在,应力得不到有效释放而产生超压.依据地层压力平衡,对走滑应力所产生的超压贡献进行了定量估算.计算结果表明,走滑应力对超压的贡献达到了30%~35%,早于大量生排烃期,极大地阻碍了油气充注.

In the JZ27-A well block of the strike-slip and compression-shear booster zone in the JZ27 section of the Liaodong Bay in the Bohai Sea area of the Tan-Lu Fault, overpressure developed in the third member of the Shahejie Formation, and the pressure coefficient reached an average of 1.5. Thick mudstones sealed the overpressure on the top. Particle fragmentation was obvious in the overpressure zone. The area and thickness of the overpressure were controlled by the range of the pressure booster zone and the intense development of strike-slip and compression-shear zone, mainly restricted to the third member of the Shahejie Formation in the JZ27-A well block. The origin for overpressure was interpreted to be as follows. From the end of the third member of the Dongying Formation to the early stage of the second member of the Dongying Formation, influenced by the intense dextral strike-slip of the Tan-Lu Fault, stress concentrated in the JZ27-A well block of the strike-slip and compression-shear booster zone. Thereby, horizontal structural compression stress formed. At the same time, because of overlying thick-bedded mudstones, stress could not be released effectively. As a result, overpressure occurred. According to the balance of reservoir pressure, the contribution of strike-slip stress to overpressure was quantitatively evaluated. The contribution of strike-slip stress to overpressure was 30%-35% and occurred earlier than the period with large amounts of hydrocarbon generation and expulsion. The overpressure impeded the charging of oil tremendously.

国家科技重大专项(2011ZX05023-006-002)资助.

https://doi.org/10.11781/sysydz201501047