Deeper Rock Acid Penetration, a Key Success Factor for the Matrix Stimulation Jobs

Abstract The operational complexity of acid stimulation in horizontal acid stimulation operations has increased and operators are drilling longer and more complex horizontal wells, which has created several challenges in terms of fluid placement and treatment effectiveness from well stimulation point of view. This paper will review the critical variables in terms of acid stimulation and production performance In order to review the topic, the stimulation optimization process will be discussed which includes the completion strategy, stimulation methods and the type of fluid used to achieve the optimum results. Different types of well completions including multi stage frac have been deployed to evaluate the best acid treatment placement in order to achieve the optimum production of the well. Moreover, different types of acid fluids were evaluated and pumped with the objective to increase wormhole penetration including a new acid technology system like single phase retarded acid to ensure the optimal stimulation impact to the rock. This paper evaluates the successful acid stimulations in similar carbonate formations using multiple acid formulation systems, which a new single-phase retarded acid reaction technology will be presented in combination with the specific pumping schedule enabled to maximize the reservoir contact and ensure open pathways for hydrocarbon to flow. The result reflects in the lower pore volume to breakthrough in the lab and it is also confirmed with the actual trial results in better production. From operational point of view, the new fluid also provided lower friction during pumping, lower mixing time during preparation of the actual job and better environmental impact compared to the baseline emulsified acid. Finally, a comprehensive treatment results evaluation was completed using the following as main variables: normalized flow back as well as the operation execution days. In this evaluation, we compare results of the acid stimulation, and confirm the benefits of the strategy and methodology for effective future acid stimulation of candidate wells.