Experimental Study on Preventing Formation Damage Due to Clay Swelling Caused by Water Based Drilling Fluid Using Aluminum Ion Based Clay Inhibitor

Formation damage is an unfavorable challenge that occurs during drilling. The present study reports the applicability of aluminum complex (AC, the combination between Al ion of aluminum sulfate (AS) and ethylenediaminetetraacetic (EDTA)) as a permanent clay swelling inhibitor in water-based drilling fluids. That is used to reduce formation damage in the near wellbore. This complex is an environmentally friendly and inexpensive additive in water-based drilling fluids (WBDFs) as a clay swelling inhibitor. In this study, some experiments, including free swelling, bentonite sedimentation, compatibility, and core flood analysis, were performed. The results have shown that AC solution can act properly as a clay swelling inhibitor at an optimal concentration of AC around 5.4 wt.%. Moreover, the compatibility test indicated that the AC additive is compatible with other common additives in WBDF. The results show that adding 8.1 wt.% of AC solution has the lowest permeability reduction compared to other concentrations. Furthermore, core flooding results showed that AC solution can act as a permanent clay inhibitor compared to KCl, a temporary inhibitor. Ultimately, the AC solution performance was not much sensitive to salinity.