Evaluating the Effects of Environmentally Acceptable Clay Stabilizer on Bandera Sandstone

Fines migration and clay swelling are major problems encountered in sandstone formations in the petroleum industry which leads to a decline in the level of productivity in the reservoirs. Inorganic salts such as KCl, NH_(4)Cl, and NaCl are used in such reservoir formations to mitigate clay particles from migrating and swelling.

The uses of these inorganic salts have temporary short term effects in the reservoirs. Cationic inorganic and organic polymers are being designed and developed to work as clay stabilizers by having a more permanent effect on these reservoirs.

Capillary suction time (CST) tests were used to evaluate existing industry-used clay stabilizers and the cationic inorganic (Al/Zr) polymer with the use of bentonite clay, and also as a screening test to qualitatively select clay stabilizing additive concentrations to be used for further tests. Coreflood experiments were done using an inorganic (Al/Zr) polymer compound at concentrations of 1, 2, and 4 wt% on Bandera sandstone core samples with temperatures ranging from 77 to 300?F.

Coreflood experiments were initially done at a temperature of 77?F and the effectiveness of the cationic inorganic polymer on Bandera sandstone core samples was analyzed and a 2 wt% concentration was determined to work best in mitigating fines migration, clay swelling, and sand production. The 2 wt% concentration of the clay stabilizing additive was also seen to work effectively at temperatures of 200?F and 300?F.

Acidizing treatments were done following a preflush of the cationic clay stabilizer on the Bandera sandstone core sample showing the stability of the clay stabilizer even after stimulation treatment.