川西大邑地区中二叠统栖霞组储层特征及发育模式

Reservoir Characteristics and Development Model of Middle Permian Qixia Formation in Dayi Area, Western Sichuan

摘要: 近期，四川盆地多口钻井在中二叠统栖霞组储层取得勘探突破，获得工业气流。然而大邑地区勘探程度较弱，目前尚无钻井，有良好的勘探潜力，同时栖霞组储层主控因素及发育模式尚存在较大争议，本次研究通过薄片观察、阴极发光和碳氧同位素测试，提出川西大邑地区栖霞组储层主要经历三个阶段：第一阶段为沉积成岩期，先后沉积了早期的斜坡相栖一段泥晶灰岩和栖二段开阔台地相生屑颗粒灰岩，浅埋藏期局部发生白云化作用而发育细–中晶白云岩和中–粗晶白云岩；第二阶段为栖霞组沉积后岩溶作用，栖二段局部地区受到岩溶作用改造，颗粒间产生裂隙溶洞；第三阶段为后期热液改造作用，栖霞组地层经热流体改造发生白云岩化作用，中–粗晶白云岩受到热液改造，裂缝溶洞内充填白云石胶结物。

Abstract: Recently, several wells in the Sichuan Basin have made exploration breakthroughs in the Middle Permian Qixia Formation reservoir and obtained industrial gas and oil. However, the exploration degree in Dayi area is relatively weak and there are no drilling wells at present, and it has good exploration potential. In addition, the main controlling factors and development models of the Qixia Formation are still controversial. Through thin section observation, cathode luminescence and carbon and oxygen isotope testing, the paper proposes that the Qixia Formation reservoir in Dayi area of western Sichuan mainly goes through three stages. The first stage is the sedimentary diagenetic stage. The early micrite of the first member of slope facies and the second member of open platform facies were deposited successively. In the shallow burial stage, local dolomitization occurred and fine-medium-crystalline dolomite and medium-crystalline dolomite were developed. The second stage is the post-sedimentary karstification of Qixia Formation. The local areas of the second member of Qixia Formation are transformed by karstification, and there are fractures and karst caves among the particles. The third stage is the late hydrothermal transformation. Dolomitization occurs in Qixia Formation after the hydrothermal fluid transformation. The medium-coarse crystalline dolomite is hydrothermal transformed and dolomite cement is filled in the fissure cave.