New Synthetic Acid Technology Used to Successfully Removing Scale Damage by Laboratory Custom-Designed Systems in HPHT Wells in Mexico´s Offshore

Abstract

Abstract Stoichiometric evaluation performed in laboratory is presented comparing conventional hydrochloric acid and Synthetic Acid based stimulation systems in static and dynamic conditions to verify the speed and reaction performance applied in real tubing segments with severe Carbonate Scale at different times verifying efficiencies. With these tests, it was determined that Synthetic Acid system showed a higher dissolution efficiency, and it was applied in the stimulation of several wells located in Mexico´s Offshore, achieving successful results. Conventionally, carbonate scale complications in tubing production, downstream pipes, wellhead choke pipes, gas lift mandrels valves and surface pipes are corrected mostly with hydrochloric acid and occasionally with organic acids; in the quest of a solution to reduce the corrosion rate in pipes, increase in reaction efficiency and stability at critical pressure and temperature conditions, a synthetic acid system was developed which meets the established objectives compared to conventional systems. Tubing production pipes with carbonate scales was recovered during minor repair and cut into segments with equal dimensions, which were measured and weighed to quantify the stoichiometry of the two types of acid. The evaluation developed to dynamic and static conditions verified the impact that the turbulence has on the efficiency and speed of reaction in different observation times. Based on the results obtained from the laboratory tests, a stimulation treatment with Synthetic Acid was carried out in the oil producing well in the BKS formation, achieving immediate increases in their operating conditions (temperature, pressure in the downstream pipe, pressure in wellhead); subsequently the well maintained an incremental trend of its flow conditions over time. The use of synthetic acid to stimulate and remove the damage by precipitation of carbonate scale present in the formation water, allows it to do so without practically causing any corrosive damage, is highly efficient in dissolution and friendly to the environment.