三塘湖盆地马朗凹陷西山窑组储层成岩作用类型及特征

三塘湖盆地马朗凹陷中侏罗统西山窑组存在多个一定规模的砂岩油气藏,具备较大的油气开发潜力。通过薄片观察、电镜扫描、X射线衍射、镜质体反射率等分析手段,划分了马朗凹陷西山窑组储集砂岩的成岩作用类型及成岩阶段,分析了成岩作用对储层物性的影响。该区西山窑组储集砂岩中发育8类成岩作用,其中蚀变、溶蚀和破裂作用为建设性成岩作用,压实—压溶、硅质胶结和碳酸盐胶结作用为破坏性成岩作用,而绿泥石胶结和交代作用会随着成岩阶段的向后推移由建设性作用转为破坏性作用;西山窑组砂岩以中成岩A期的晚期阶段为主。压实作用是该区主要的减孔因素,高岭石化和溶蚀作用是主要的増孔因素。发育绿泥石环边胶结,储集空间为剩余原生粒间孔与溶蚀孔组合的砂岩是最优质的储集砂体。

Diagenesis types and characteristics of Xishanyao Formation in Malang Sag,Santanghu Basin

There are many large-scale sandstone reservoirs in the Xishanyao Formation of the Malang Sag, Santanghu Basin, with great potential for oil and gas development. The diagenesis types and stages of the reservoir were studied by means of thin section observation, scanning electron microscopy, X-ray diffraction, vitrinite reflectance, etc. Based on this, the influence of diagenesis on the reservoir was analyzed. Eight types of diagenesis were developed in the sandstone reservoirs of the Xishanyao Formation in the study area. Constructive effects include rim chlorite cementation, alteration, dissolution and rupture, while the main destructive diagenesis includes compaction, pressure solution, and siliceous and carbonate cementation. In addition, the cementation and metasomatism will change from constructive to destructive with the backward transition of the diagenetic stage. The sandstones of the Xishanyao Formation in the study area are mainly in the late part of the middle diagenetic A stage. Compaction is the main reason for porosity reduction, while kaolinite and dissolution are the main causes for porosity increase. Chlorite rim cementation developed. The sandstones with remaining primary intergranular pores and dissolution pores are the most favorable reservoirs.