Melut盆地P地区白垩系Galhak组岩性圈闭识别及其勘探意义

Identification and exploration significance of lithologic traps in Cretaceous Galhak Formation in P area of Melut Basin

以Melut盆地P地区白垩系Galhak组为例,从井筒资料出发,采用高分辨率层序地层学分析、地震属性分析、波阻抗反演等地震储层横向预测技术和储层建模技术,在确定Galhak组层序框架、沉积相和储层分布特征的基础上,结合现今及古构造特征,进行岩性圈闭识别与评价。P地区白垩系Galhak组岩性油气藏发育在湖侵体系域的三角洲前缘水下分流河道微相。解剖了已发现的白垩系Galhak油气藏,确定岩性圈闭的成藏条件、主控因素为输导系统和局部泥岩盖层。由于近源优势,P地区白垩系Galhak组具有发育岩性油气藏的有利地质条件,局部盖层发育的地区和剖面上反向正断层的上升盘为白垩系Galhak组岩性圈闭勘探的有利构造部位。Galhak-Ⅳ段是Galhak组岩性圈闭发育的最有利层段。Melut盆地岩性油气藏具有广阔的勘探前景。

Based on the geological,borehole and seismic data,the sequence framework,the sedimentary facies and the reservoir distribution of Cretaceous Galhak Formation in P area of Melut Basin are determined using high-resolution sequence stratigraphy analysis,seismic attribute analysis,seismic impedance inversion and reservoir modeling techniques. The lithologic traps in Galhak Formation are identified and evaluated by combining the sequence framework,the sedimentary facies and the reservoir distribution with the current and ancient tectonic features of P area. The lithologic traps in Galhak Formation develop in distributary channel microfacies of braided river delta front in transgressive systems tract( TST). It is held that the key factors to the formation of the lithologic traps in Galhak Formation are hydrocarbon migration system and local mudstone cap-rocks according to the analysis of the discovered oil reservoirs in Galhak Formation. Due to near the source rock,in Galhak Formation of P area there are favorable geological conditions to the development of lithologic hydrocarbon reservoirs. The areas where local cap-rocks develop and the upthrowns of reverse normal faults are favorable structural location to the exploration of lithologic traps in Galhak Formation. The fourth member of Galhak Formation is the most favorable layer to the exploration of lithologic traps. Melut Basin is of broad prospect for the exploration of lithologic traps.