鄂尔多斯盆地姬塬油田东部长82油层组储层酸敏特征及主控因素

基于X-射线衍射、扫描电镜、薄片鉴定以及酸敏实验等测试分析手段，对鄂尔多斯盆地姬塬油田东部长8₂油层组储层酸敏性进行分析。结果表明:储层黏土质和钙质胶结严重，非均质性强，主要的酸敏矿物为绿泥石和方解石/铁方解石，储层酸敏性主要以改善型—弱酸敏型为主；酸敏实验中，部分原始大孔隙样品出现减孔现象，主要是部分绿泥石包膜及针叶状晶体溶蚀、崩落所致，实验中Fe(OH)₃沉淀及凝胶体在短时间内对储层酸敏性影响有限，方解石/铁方解石的溶解能有效补偿Fe(OH)₃沉淀及凝胶体对储层的影响；在碳酸盐胶结物富集区，CaF₂沉淀是储层物性变差的直接因素，总体呈现出盐酸对储层的改善程度要好于土酸；酸敏矿物较发育于水下分支河道微相，并呈现出近物源区绿泥石胶结物含量较高、远物源区方解石/铁方解石胶结物含量较高的分布特征；酸敏矿物的含量、类型、分布受沉积物源、沉积微相以及成岩作用等控制，特别是有机质热解-脱羧作用在成岩过程中与溶蚀作用、交代作用相伴生，对酸敏矿物的形成、类型及赋存状态具有重要影响。

Acid Sensitivity Characteristics of Reservoir and Main Controlling Factors of Chang-82 Oil-bearing Interval in Eastern Jiyuan Oilfield of Ordos Basin,China

Based on XRD, SEM, slice image and acid sensitivity experiment, the acid sensitivity of reservoir of Chang-8₂ oil-bearing interval in the eastern Jiyuan oilfield of Ordos Basin was analyzed. The results show that the acid sensitivity of reservoir of Chang-8₂ oil-bearing interval is dominated with amendment-weak sensitivity; clay and calcareous cements of reservoir are serious, the heterogeneity is strong, and the main acid sensitivity minerals are chlorites and calcite minerals; the relative large porosities of some samples are reduced by the spallation of partial coniferous chlorite and chlorite film, which blocks the porosities and throats in the acid sensitivity experiment; meanwhile, the effects of the precipitation of ferric hydroxide (Fe(OH) ₃) and gel on the reservoir physical properties are limited, and the corrosion of calcareous cement compensates the negative effects on reservoir; whereas, the calcium fluoride (CaF₂) is the direct factor to the damage of physical properties in acid sensitivity experiment, indicating that the hydrochloric acid is more suitable for the reservoir improvement than mud acid; the underwater distributary channel is the suitable place for the development of acid mineral, including that the chlorite and calcite/ferrocalcite, and the chlorites cement with high content distribute well near the provenance, while the distribution of a relative high content of calcites/ferrocalcites is far away from provenance; the contents, types, and distribution of acid mineral are controlled by sedimentary provenance, sedimentary microfacies and diagenesis, especially the thermolysis and decarboxylation of organic material in Chang-8₂ oil-bearing interval occur along with the dissolution and metasomatism during the diagenetic stage, having an important influence on the formation, types and the existence condition of acid mineral.