Sai202 well area is main production area of Ansai oil field. Chang 61Sandstons,which is constituted of low composition maturity feldspathic sandstone, is main producing formation. The merits of reservoir properties is the main factor affecting productivity, while reservoir properties is closely related to diagenesis. Based on the analysis techniques such as thin-slice, cast-slice observation, SEM and cathodeluminescence, the diagenetic characteristics and its influence on the Chang 61 reservoir of Sai 202 well area in Ansai oilfield have been studied. The Chang 61 reservoir diagenesis is in the middle diagenetic stage B. The reservoirs underwent mechanical impaction, cementation, dissolution, metasomato-sis and fracturing. Dissolution including dissolution of feldspar, calcite and laumontite are the main factors making reservoir physical property better, and the development of microfractures also improved reservoir physical property. Dissolution development zone is the oil-rich zone. In search of dissolution development zone in oil and gas exploration is a major geological problem to be solved.%安塞油田塞202井区长61是主力产层,储层为长石砂岩.影响产能的的主要因素是储层物性的优劣,而储层物性与受成岩作用密切相关.利用砂岩薄片、铸体薄片、扫描电镜、阴极发光等分析测试方法,研究了安塞油田塞202井区长61油层段储层的成岩作用特征.长61储层经历了压实作用、胶结作用、溶蚀作用、交代作用和破裂作用等成岩作用.按照成岩作用对储层的影响,可以把长61的成岩作用分为3类:破坏性成岩作用、建设性成岩作用和二重性成岩作用.溶蚀作用产生次生孔隙,使储层物性显著改善,是最主要的建设性成岩作用.寻找溶蚀作用发育带是油气开发中要解决的主要地质问题.
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