砂砾岩储集层的成岩作用及孔隙演化——以准噶尔盆地红车拐地区三叠系百口泉组为例

准噶尔盆地三叠系百口泉组油气勘探潜力巨大,但储集砂体物性较差,非均质性较强,优质储层形成原因尚未明确,成岩相关特征认识模糊,限制了该区油气的勘探开发。基于三叠系百口泉组岩芯观察,结合薄片分析、扫描电镜以及物性分析等资料,分段分岩性对储层成岩作用以及孔隙演化进行了详细分析。结果表明,研究区百口泉组岩石类型以砂砾岩为主,储层按岩性可划分为砂砾共同支撑储层和砂质颗粒支撑储层,储集空间整体以原生粒间孔为主,储层物性较差,属于低孔低渗型。储集层的成岩阶段为中成岩B期。基于定量分析,发现压实作用和胶结作用对储集层物性破坏较大,溶蚀作用增孔能力受控于岩石支撑类型,对砂砾共同支撑的储集层岩石增孔影响较大,对砂质颗粒支撑的储集层岩石增孔影响较差。

Diagenesis and pore evolution of sandy conglomerate reservoirs: A case study from Triassic Baikouquan Formation in Hongcheguai area of the Junggar Basin

The Triassic Baikouquan Formation in the the Junggar Basin has huge oil and gas exploration potential, but the reservoir sand body has poor physical properties and strong heterogeneity. The reason for the formation of high-quality reservoirs is not yet clear, and the understanding of diagenetic characteristics is vague, which limits the exploration and development of oil and gas in this area. Based on the core observation,thin section analysis, scanning electron microscopy and physical property analysis, the diagenesis and pore evolution of the reservoir from the Baikouquan Formation are analyzed in detail. The results indicate that the rock type of the Baikouquan Formation in the study area is mainly sandy conglomerate, and the reservoir can be divided into reservoir supported by sand and gravel and supported only by sand. The overall reservoir space is mainly composed of primary intergranular pores with poor physical property, belonging to the low porosity and low permeability type. The diagenetic stage of the reservoir is the middle diagenetic stage B. Based on quantitative analysis, it was found that compaction and cementation have a significant impact on the physical properties of the reservoir. The pore increasing ability of dissolution is controlled by the type of rock support, and has a significant impact on the pore increasing of reservoir rocks supported by sand and gravel, while it has a relatively poor impact on the pore increasing of reservoir rocks supported by sandy particles.