Testing and analysis of potential damage factors in carbonate reservoir

The pollution damage of injected water, fracturing fluid and drilling fluid in carbonate reservoir are mainly studied, however, the potential product precipitation damage have been seldom studied. Majiagou Formation in Daniudi gas field mainly has two kinds of rock samples, one with dolomite as the main component and the other with gypsum as the main component. On the one hand, through mineral composition analysis, the main composition of dolomite sample is CaCl2 and MgCl2. Then the ion concentration of acid rock reaction product solution was tested, the results show that the highest Ca2+ content and the highest Mg2+ content in the four groups are lower than the lowest solubility of Ca2+ and Mg2+, so the products will not reach supersaturated state and precipitate in the solution. On the other hand, for the rock sample dominated by gypsum, the quality of rock plate changes little after water immersion and acid solution corrosion. Then the gypsum samples were subjected to acid displacement, and the surface morphology changes of the samples were observed and the mass changes were measured. The test results showed that the dissolution amount of the samples was small. Therefore, it shows that water and acid will not react with gypsum and will not produce potential precipitation.