灰质白云岩可溶性影响研究OA北大核心CSTPCD

Objectives Since there are fewer studies on the dissolution of carbonate rocks with similar compo-sition of calcite and dolomite content under normal temperature and pressure,in order to reveal the dissolu-tion characteristics of this kind of rocks,Methods it selected gray dolomite as the test object to carry out dissolution simulation tests under different acidic and flow conditions at normal temperature and pressure to explore the factors influencing the dissolution rate of gray dolomite by analyzing the dissolution parameters of carbonate rockssuch as pH of the acid solution,the quality of the specimen and the change of the pore space,and the amount of calcium and magnesium ions release.Results Results show that:(1)When acid pH≤3,H+consumption is larger than calcium and magnesium ion generation,and the conductivity value shows a rapid decreasing trend,when acid pH＞3,H+consumption is slightly larger than calcium and magnesium ion generation,and the conductivity shows a slow decreasing trend,and acid pH=3 is the key point of the turn of the conductivity value from large to small,which highlights the relationship between the consump-tion of H+and the generation of calcium and magnesium ions.(2)The dissolution rate and amount of calcite in gray dolomite is much higher than that of dolomite,and the dissolution effect is more obvious under the condition of higher initial acid molar concentration.(3)An increase in the number of pores increases the contact area between the rock and the acid solution,which in turn accelerates the rate of rock dissolution.(4)Filling of rock pores with impurities reduces acid damage to the rock.(5)High molar concentration of acid(pH≤3)has a higher dissolution ratein the stronger flow state environment,and has a stronger ability to dissolve soluble substances on the rock surface.When the molar concentration of acid is lower(pH≥4),the change of flow state has less effect on the dissolution rate.Conclusions The results of the study can pro-vide reference for carbonate rock dissolution research,dissolution degree evaluation and engineering con-struction.