Evaluation of Custom Acid Formulations in Sand Control Operation: Case Studies and Key Lessons

Abstract Cased hole gravel packing is a widely used sand control technique in the oil and gas industry to prevent sand production and maintain well productivity. In reservoirs with unconsolidated sand, implementing effective sand-control practices is crucial to prevent the production of reservoir sand. In addition to sand production, clay and fines migration pose major challenges, potentially resulting in production impairment or leading to failures. Certain reservoirs may contain fine particles or other obstructions that can hinder the effectiveness of gravel pack placement and well productivity. For this case, improvements to conventional cased hole gravel pack placement were initially pursued using high-rate water pack (HRWP) or fracture and pack gravel (FPG) techniques. Along with these placement technique improvements, there is also the risk of formation damage from incompatible brine or other introduced fluids/solids, as well as formation fines content, especially in Plio/Pleistocene sandstones with low resistivity. Sandstone acidizing is also considered to enhance reservoir permeability and productivity by dissolving and removing formation damage, such as formation fines, mud solids, and potential scale from the pore spaces and near-wellbore region of sandstone reservoirs. This paper provides insights into the custom acid formulations comparing to the conventional sandstone acid/mud acid recipe (with hydrofluoric acid (HF) and hydrochloric acid (HCl).) treatments, with a comprehensive laboratory testing results focused on improvement, not only for near-wellbore treatment but also for deeper penetration and fines stabilization wherever possible. The importance of these formulations being tailored to the specific needs of the reservoir ensures that they are not only effective but also efficient for the sand control.