The interactions between carbonate and H2S saturated acid fluid at various temperatures and pressures in-situ conditions were simulated using hydrothermal diamond-anvil cell equipment combined with Raman spectroscopy. The heating process is from room temperature to 230?C and then the system is cooled to room temperature again. Experimental results clearly demonstrate that carbonate minerals present much precipitation from room temperature to 140?C and little precipitation from 140?C to 230?C. Carbonate trends to precipitate with the increase of temperature and pressure, and dolomite is more stable than calcite and limestone. But in the cooling process carbonate suffers from little dissolution. So in the burial process, carbonate trends to precipitate, and the rapid closed burial and slow uplift process is beneficial to form high quality reservoirs in the deep closed condition. Fault and magmatic hydrothermal activities may break the closed system, which needs further study.

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.