Abstract: There are two numerical models for theory analysis of smectite-illite transformation at present in the world, including the first-order thermal reaction equation and the dissolution-precipitation equation. The first-order thermal reaction equation has been widely introduced into basin modeling. This equation adopted the law of mass action, but did not completely follow the compound reaction. The thermal parameters were only related to temperature and burial time over 250℃. The dissolution-precipitation equation followed the compound reaction and was based on the mechanism of smectite dissolution in free pore water and subsequent precipitation of illite. This equation was related to not only temperature and burial time but also to the variety of rock matrix and pore fluid during sedimentary compaction. On the basis of the works of pioneer contributors, the dissolution-precipitation equation was improved and used in basin modeling. The corresponding module was programmed and successfully applied to several basins. The theory and practice proved that the dissolution-precipitation equation is better than the first-order thermal reaction equation.

Key words: basin modeling, diagenetic history, smectite-illite transformation, thermal reaction equation, dissolution-precipitation equation, numerical model

摘要： 目前世界上关于蒙皂石向伊利石转化有两类理论分析数值模型,即一级热反应方程和溶解沉淀方程。一级热反应方程采用质量作用定律,已较广泛地引入盆地模拟。但热参数在250℃以上的高温实验条件下没有完全遵循混合反应,仅与地温和埋藏时间相关;溶解沉淀方程遵循混合反应,基于蒙皂石在自由孔隙水中溶解、随之发生伊利石的沉淀这一原理,不仅与地温和埋藏时间相关,而且与沉积压实引起的骨架和孔隙流体变化相关。在前人的工作基础上,对溶解沉淀方程做了改进,使之适用于盆地模拟。研制了相应的软件模块,并在几个盆地的计算中获得成功。理论与实践证明,溶解沉淀方程优于一级热反应方程。

关键词: 盆地模拟, 成岩史, 蒙皂石向伊利石转化, 热反应方程, 溶解沉淀方程, 数值模型