Preparation and application of a barium sulfate descaling and deblocking agent for low-permeability reservoirs

Abstract

During water injection development in low-permeability reservoirs, BaSO₄ scaling is prone to occur due to incompatibility between high-salinity formation water and injected water, severely affecting oilfield development efficiency. This paper systematically developed and evaluated the performance of a composite BaSO₄ scale remover. Chelating agents, conversion agents, dispersants, and penetrants were optimized to construct an efficient composite scale removal system. Combined with core flooding experiments, operational parameters and processes were optimized. The results show that an efficient scale removal system was developed: 15% DTPA-5K + 8% C₆H₁₁O₇Na + 6% DTPMP + 0.2% JFC (balance water), achieving a scale removal efficiency of 98.4% at pH = 11. Simulated core experiments indicated a permeability recovery rate of 87% at an injection rate of 0.02 mL min⁻¹ and an injection volume of 1.5 PV. Field applications demonstrated that this system effectively removes BaSO₄ scale blockages in injection and production wells. For injection well A21, the injection pressure decreased by 20.8%, water injection volume increased by 200%, and liquid production increased by 136% after treatment. For production well P17, liquid production increased by 136%, oil production increased by 148%, and flowing pressure increased by 31.8%. The research results provide theoretical basis and technical support for the prevention and treatment of BaSO₄ scale in low-permeability reservoirs.