苏里格气田西部盒8段储层成岩作用及其演化

Diagenesis and evolution of reservoirs in the He-8 member,west Sulige gas field

为揭示苏里格气田西部下二叠统石盒子组第8段(简称盒8段)相对优质储层的时空展布规律并给储层预测提供依据,基于铸体薄片、扫描电镜、X光衍射和电子探针等分析化验资料,对盒8段储层的成岩作用及其演化进行了研究。结果认为:①盒8段储层岩石类型主要为岩屑石英砂岩,其次为石英砂岩,碎屑颗粒组合具有高石英、高岩屑、低长石的特点,填隙物以杂基和硅质为主;②该储层经历的成岩作用中,压实作用、胶结作用和交代蚀变作用对孔隙发育主要起到破坏性影响;溶蚀作用和破裂作用主要对孔隙发育起建设性作用,特别是溶蚀作用形成的大量次生孔,成为主要储集空间;③胶结压实相与强溶蚀相组合为最有利的储层发育区,胶结压实相与中等溶蚀相组合属于较有利储集层发育区,相对优质储层主要发育于冲积平原的主河道和三角洲平原的分流河道上且与溶蚀作用所形成的次生孔的分布及胶结物的类型、含量有着紧密的关系。

Based on analyses of cast thin section, SEM, X-ray diffractions and Electron Probe data, diagenesis and evolution of the reservoirs in the 8th member of Lower Permian Shihezi Formation (abbreviated for He-8 member), the western Sulige gas field, were studied to reveal the temporal and spatial distribution of the relatively quality reservoirs and to provide a basis for reservoir prediction. The following conclusions were obtained. The rock types of the He-8 member reservoirs are predominantly of lithic quartz sandstone, followed by quartz sandstone. The lithic combination is high in content of quartz and lithic but low in content of feldspar and interstitial matters are dominated by matrix and siliceous cements. Compaction, cementation and metasomatic alteration are destructive to the development of pores, while dissolution and fracturing are constructive. The reservoir spaces are mainly composed of numerous secondary pores resulted from dissolution. The combination of cementation-compaction facies with strong dissolution facies is the most favorable for reservoir development, while the combination cementation-compaction facies with moderate dissolution facies is relatively favorable for the development of reservoirs. The relatively quality reservoirs are mainly developed in the main channels on alluvial plain and the distributary channels on delta plain. They are closely related with the distribution of secondary pores from dissolution, as well as the types and contents of cements.