Potential Formation Damage Following Matrix Acidizing Treatments. North Africa Field

Abstract

Abstract Sludges formation during acid stimulation is a serious issue as it induces a damage that cannot be easily dissolved with most of treating chemicals. Recently, many wells experienced a drop in their potential following matrix acidizing treatment. Many factors could be attributed to this poor production performance following the treatments. In this paper, we addressed the issue of sludge formation in contact of the acid (HCl 7.5% & Mud acid 6:1.5) with crude oil. As described by Moore et al (1965), sludge tendency test was carried out in the laboratory using samples of acid recipe being used in the field with samples of oil collected from wells with suspected sludge issues. Surprisingly, results show sludge formation in contact of both HCl 7.5% and Mud Acid 6:1.5. The sludge deposit formed was dried in oven and both volume and weight percentage were calculated and compared with published values of different crude oils around the world. Some case examples with suspected formation damage by sludges are presented in this paper.