基于模拟实验的原位观察对碳酸盐岩深部溶蚀的再认识

Re-recognition of Deep Carbonate Dissolution Based on the Observation of in-situ Simulation Experiment

结合川东北地区古地温梯度,利用金刚石压腔(DAC)技术,针对碳酸盐岩设计了一套全新的随埋深增加的水-岩作用模拟实验。模拟实验结果表明,随着地层温度、压力升高,灰岩表现为明显的胶结(沉淀),白云岩在高温高压的酸性地层流体条件下不比灰岩更易溶蚀,说明在封闭-半封闭的埋藏过程中碳酸盐岩不存在大范围的"溶蚀窗"。实验结果可能导致对碳酸盐岩深部储层发育机理的重新认识。

A set of new carbonate dissolution in-situ experiments was designed to simulate the real burying process and to test its affection on fluid-rock reaction. By adoption DAC, the experimental process was controlled by the heater according to the paleothermal gradient of NE Sichuan. Experiment results indicate that limestone show precipitation with the increase of temperature and pressure. Dolomite is more stable than limestone in the whole experimental process, which shows a quite different result from the standpoint that dolomite is more dissoluble than limestone in high temperature and high pressure conditions. The ＂dissolution window＂ was not observed in the whole experimental process. The experimental researches may provide some new perspectives to the recognition of the formation and preservation mechanism for the deep carbonate reservoir.