DOLOMITE MINERAL EFFECTIVENESS ON THE SANDSTONE RESERVOIR PERMEABILITY

Abstract

The matrix rock formation acidization technique might be a regular mode to improve the sandstone rock permeability surrounding the wellbore. The dolomite rock (CaMg(CO3)2 can plug the pay zone around the wellbore and cause permeability reduction action into the oil sandstone reservoir. Ergo, the oil flow rate can be cut down due to presence of the dolomite carbonate minerals into the pore space that originally was vacant of it. Therefore, the change in the permeability value and flow rate are investigated into the Sandpack permeameter set up at different dolomite content which followed by 15%wt. hydrochloric (HCL) acid concentration injection to remove dolomite mineral composition and to improve sandstone formation permeability. The constant head permeability test has been conducted to measure the permeability of the sandstone reservoir at different dolomite concentration value. The obtained results shown that at the lowest dolomite content (Xmin) of 26.6%, the sandstone reservoir porosity substantially decreased to value equal to 21% which the porosity originally was 42%. Similarly, the water flow rate and permeability were 2.5 cc/sec and 12.11 D respectively, at the no dolomite mineral in the Sandpack, however, the water flow rate and permeability were cut down to 1.316 cc/sec and 8.5 D respectively, at dolomite content (Xmin) of 26.6% of the total grain volume. Besides, the HCL acid injection job can return the sandstone formation permeability to the original value of 42%. In conclusion, Carbonate rock minerals such as dolomite can cause damage to the sandstone reservoir. However, the HCL acid has a remarkable positive impact to remove the dolomite minerals damage from the sandstone reservoir surrounding the wellbore