Quaternary amine-based chemicals have been used for many years as clay stabilizers. An Al/Zr-based clay stabilizer, A, was developed. It showed great effectiveness in mitigating fines migration and overcame the leaching effect of HCl. In this study, Stabilizer A was examined and its performance was compared with two commercial clay ones: tetramethyl ammonium chloride and choline chloride.
The type of cores (6 in. length and 1.5 in. diameter) that were used is Berea sandstone of 60-85 md; mainly contained 5 wt% kaolinite. Various coreflood experiments were performed to assess the effectiveness of each of the three stabilizers at 200 and 300°F. Inductively Coupled Plasma was used to analyze the core effluent to measure the concentrations of key cations.
During tetramethyl ammonium chloride and choline chloride corefloods, significant amount of fines were noted in the core effluent samples, which means that these stabilizers were not effective. A bad odor of ammonia was noted during mixing of choline chloride with HCl acid. Choline chloride was effective at high concentrations. Stabilizer A showed good behavior during coreflood experiments, and proved to be better than the two commercial stabilizers at low concentrations. Stabilizer A worked very well, and no bad smell or fines were produced. In addition, Stabilizer A is an inorganic-based fluid, environmentally friendly, and does not have any smell; in contrast to quaternary amine chemicals. Unlike previous Al-based stabilizers (hydroxy aluminum solutions), the new stabilizer was not removed by HCl and no decline in permeability was noted following HCl injection.