碳酸盐岩—膏盐岩组合水—岩反应热力学和动力学模型及其在塔北地区寒武系储层的应用

Thermodynamics and kinetics model of fluid-rock interaction in carbonate-evaporite paragenesis and its application in Cambrian reservoir in Tabei area,Tarim Basin

埋藏过程中,碳酸盐矿物和石膏组合的溶解—沉淀对深埋条件下的岩溶和孔洞保持具有至关重要的影响。以塔北隆起寒武系储层为研究对象,根据英买、牙哈地区14口井及轮探1井的地层水离子含量,建立水—矿物相互作用的热力学和动力学模型,结合孔隙度及薄片分析,开展碳酸盐岩—膏盐岩组合型储层的精细评价。结果显示,碳酸盐矿物和石膏的溶解—沉淀反应速率与其ΔG呈较好的指数关系,溶解速率随着ΔG的减小而增大,而沉淀速率随着ΔG的增大而增大。计算结果表明塔北隆起寒武系埋藏环境总体上有利于碳酸盐矿物—石膏组合的溶解,西北部地区岩溶作用强于东南部,有利于储层孔洞的保持,与实际的储层物性测试结果基本吻合。该研究为深埋碳酸盐岩—膏盐岩组合型储层有利储集区的定量预测及评价提供了新方法。

The dissolution and precipitation of carbonate and gypsum have a great impact on burial karst and pore preservation during burial process.In order to carry out the fine evaluation of carbonate-evaporite compos⁃ite reservoir,we take the Cambrian reservoir in Tabei Uplift of Tarim Basin as the object,and establish the thermodynamics and kinetics models of fluid-mineral interaction according to the formation water ion content from 14 wells in Yingmai and Yaha areas and Well Luntan 1,combined with petrologic characteristics such as thin section observation and porosity.Results showed that the dissolution and precipitation reaction rate of car⁃bonate minerals and gypsum and itsΔG relationship is a good index,dissolution rate increases with the decrease ofΔG and precipitation rate increases with the increase ofΔG.Calculation results show that Tabei Uplift Cam⁃brian buried environment in general is beneficial to the dissolution of carbonate mineral gypsum combination and karstification is stronger in the northwest than that in the southeast,which is in good agreement with the test re⁃sults of reservoir physical properties.This study provides a new method for quantitative prediction and evalua⁃tion of the favorable reservoir area of the deep burial carbonate-evaporite paragenetic association reservoir.