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在对大量薄片和岩心观察分析基础上,结合扫描电镜和全岩分析、X衍射粘土分析、包裹体测温等手段,对查干凹陷碎屑岩储层的成岩作用和孔隙演化进行了研究。结果表明:研究区碎屑岩储层主要为低成分成熟度、低结构成熟度的长石岩屑砂岩,成岩作用呈现“强压实、强胶结、弱交代、弱溶蚀”的“两强两弱”特征;成岩阶段主要处于中成岩A期,局部达中成岩B期至晚成岩期。两期胶结主要发生在苏二早期和乌兰苏海时期,中浅层(<2 500 m)较低孔隙度主要由于强压实和早期致密胶结所致;较高孔隙度是由于原生孔隙保存较好,长石及碳酸盐胶结物的溶蚀作用导致孔隙度增大。深层碎屑岩储层(>2 500 m)较低孔隙度除压实作用外,碳酸盐致密胶结是主因;较高孔隙度则为早期酸性溶蚀叠加晚期碱性溶蚀产生次生孔隙为主。晚期碱性溶蚀发生在油气充注之后,为无效溶孔。
Based on the observation and analysis of a large number of thin slices and cores, the diagenesis and pore evolution of the clastic reservoirs in the Chagan Depression were studied by means of scanning electron microscopy and whole rock analysis, X-ray diffraction analysis and temperature measurement of inclusions. The results show that the clastic reservoirs in the study area are mainly feldspathic lithic sandstones with low compositional maturity and low structural maturity, and the diagenesis shows “strong compaction, strong cementation, weak metasomatism and weak dissolution” Two strong and two weak "features; the diagenetic stage is mainly in the A diagenetic stage, part of the mid-stage diagenetic B to late diagenetic stage. The two cements mainly occurred in the early Su II and the Ulan-Su sea periods. The lower porosity in the middle and shallow layers (<2500 m) was mainly due to strong compaction and early tight cementation; the higher porosity was due to the preservation of primary pores Preferably, dissolution of feldspar and carbonate cements results in increased porosity. Lower clastic rock reservoirs (> 2 500 m) lower porosity except for compaction, carbonate cementation is the main reason; higher porosity is the early acid erosion superimposed late alkaline corrosion secondary pores are the main . Late alkaline corrosion occurred after the filling of oil and gas, as invalid dissolved pores.