Abstract:

Dolomitization has a significant influence on the carbonate rock reservoirs which contain oil and gas resources. Previous studies mainly focus on formation models of the dolomite, however, a fair description of its formation process is quite rare, needless to say a reasonable quantitative analysis for the transformation level of the reservoir by dolomitization. In this paper, a 1-D model was set up based on the seepage reflux dolomitization model. Under the comprehensive advantage of TOUGHREACT, a multicomponent multiphase flow and solute transport simulation software, the exploration on the transformation of the reservoir by dolomitization is fully realized. As the obvious results illustrate: when the concentrated sea water with high Mg/Ca ratio intrudes into the aquifer, calcite dissolution and dolomite precipitation are inevitable and actually happen in this case. The porosity and permeability are greater than the initial value. In 50,000 years, by force of gravity, seepage reflux dolomitization can affect 50 m depth of the reservoir resulting in the formation of a certain scale dolomite reservoir.

Key words: dolomitization, seepage reflux, physical properties of reservoir, TOUGHREACT