乙酸条件下方解石溶解特征及其地质意义

 针对方解石溶解的显微岩相学特征难以识别的问题，以纯净方解石为对象，依据松辽盆地扶余油层地质条件，通过乙酸-方解石相互作用实验，研究了方解石的溶解特征及其地质意义。结果表明，方解石在不同温度下发生尺度不同的溶解作用及质量损失，离子质量浓度呈现规律性变化，Ca²⁺离子浓度为684.68～1255.25 mg/L，HCO₃^-离子浓度为2239～3821 mg/L，矿化度为3088～5456 mg/L；方解石溶解的显微岩相学特征包括残余锥、残余细晶叠瓦状排列、齿状残余锥、瘤状残余锥及尖锐残余锥等；乙酸条件下方解石最适合的溶解温度为100～130℃。这项研究可为方解石溶解地质特征鉴定、油气藏储层成岩作用及次生孔隙预测等提供一定的理论基础。

Characteristics and geological significance of calcite dissolution under acetic acid conditions

Since it is difficult to identify microscopic petrographic features of calcite dissolution, we take, pure calcite as the research object, and base on the Fuyu reservoir geological conditions of Songliao basin to study the calcite dissolution characteristics and geological significance through acetic acid-calcite interaction experiments. Results show the followings. Ccalcite is found of having different scale dissolutions and mass losses in different temperatures; ion concentration show regular changes, with Ca²⁺ ion concentration being 684.68~1255.25 mg/L, HCO₃^- ion concentration 2239~3821 mg/L, salinity 3088~5456 mg/L; calcite dissolution microscopic features include residual cone, residual fine crystal imbricate arrangement, dentate residual cone, tumor residual cone, residual sharp cone, etc.; under the acetic acid condition the most suitable temperature for calcite dissolution is 100~130℃. This study provides a certain theoretical basis for the identification of geological features of calcite dissolution reservoir and the function of reservoir into rock, and secondary porosity prediction.