印度扇近海盆地重磁场融合与油气盆地构造解析

Tectonic division of the Offshore Indus Basin by integrated gravity and magnetic study

  • 摘要: 印度扇近海盆地是巴基斯坦海域重要的油气勘探目标区,但盆地尚处于勘探早期,受限于勘探资料的数量和品质,对盆地内部结构认识不够清晰,制约了该地区油气调查工作的进一步深入。以新一代卫星测高重力异常数据(V29.1)和EMGA2地磁网格数据(V2)为基础,利用重、磁场融合技术得到印度扇近海盆地及邻区重磁场融合结果,并对该研究区盆地内部油气构造格架进行研究。通过研究表明,重磁场融合结果能够很好刻画印度扇近海盆地内部结构:低磁低重对应盆地沉积坳陷区,高磁低重对应有岩浆岩侵入的坳陷区,高磁高重对应盆地隆起区,低磁高重对应碳酸盐岩台地区;结合钻井和二维地震资料,推断印度扇近海盆地呈现“三坳两隆”的构造格架,且受不同期次构造运动的影响,盆地“东西分块”特征明显。本次新划定盆地西南部的西部坳陷、西部隆起,南部坳陷面积增大,盆地南缘位于帕拉蒂纳脊附近。该研究成果为印度扇近海盆地及邻区基础地质、油气勘探研究提供依据。

     

    Abstract: The Offshore Indus Basin (OIB) is an important oil and gas exploration target area in Pakistan sea area. The exploration of the basin, limited by the quantity and quality of exploration data, is still in the early stage, which restricts the oil and gas investigation in this area. Based on the new generation of satellite altimetry gravity anomaly data (V29.1) and magnetic data from the Earth Magnetic Anomaly Grid (EMAG2-V2), the integrated gravity and magnetic field technique was applied to study the tectonic framework of the OIB, with which the integrated gravity and magnetic field was established and the structure of the OIB was interpreted. Results show that the areas of low-value magnetic and low-value gravity correspond to the sedimentary depressions, while those of high-value magnetic and low-value gravity correspond to the depressions with magma intrusions, whereas the areas of high-value magnetic and high-value gravity correspond to the uplift areas of the basin, and the areas of low-value magnetic and high-value gravity correspond to the carbonate platforms. Combined with the ocean drilling and 2D seismic profile data, three depressions and two uplifts in E-W in the OIB were inferred. Based on the previous tectonic division, the western depression and the western uplift in the southwestern corner of the basin were re-defined, the scope of the southern depression was expanded, and the southern edge of the basin was extended to near the Palatina ridge. This study provided evidence for basic geological and oil-gas exploration in the OIB and its adjacent areas.

     

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