渤海油田油井缓冲直排酸体系的研究与应用

Research and Application of Buffered Direct Discharge Acid System in Oil Wells of Bohai Oilfield

  • 摘要: 渤海油田生产过程中易因结垢造成产能下降,采用常规酸化解堵时残酸返排需中和,易导致原油乳化、设备腐蚀及生产流程中断等问题,而现有螯合中性解堵剂普遍存在溶蚀能力不足、易产生二次沉淀等缺陷。针对上述问题,研发了一种缓冲直排酸体系,该体系以低相对分子质量羧酸及其铵盐为主剂,复配少量盐酸、氟化氢铵、氢氟酸及羟基亚乙基二膦酸(HEDP)与柠檬酸复合铁离子稳定剂,通过二次pH值调节机制实现残酸 pH 值稳定在5~7,可直接返排。性能评价表明,缓冲直排酸体系前置液对碳酸钙溶蚀率达75.25%,处理液对膨润土及现场岩屑的溶蚀率分别为34.70%和15.73%~20.91%,铁离子稳定能力达175 mg/L,综合性能优于或接近常规酸液。该体系在渤海油田多口井现场应用后,产油量增加38%~118%,返排液无需中和即可直接进入生产流程,解堵效果与流程适应性良好,为海上油田高效安全酸化解堵提供了新技术支撑。

     

    Abstract: In the Bohai Oilfield, production capacity decline is often caused by scaling during production. Conventional acidizing for plugging removal faces issues such as the need for neutralization of residual acid flowback, susceptibility to crude oil emulsification, equipment corrosion, and production process interruption, etc. Meanwhile, existing chelating neutral plugging removal agents generally suffer from insufficient dissolution capacity and susceptibility to secondary precipitation. To address these challenges, a buffered direct discharge acid plugging removal system was developed. This system used low-molecular-weight carboxylic acids and their ammonium salts as the main agents, supplemented with a small amount of hydrochloric acid, ammonium bifluoride, hydrofluoric acid, and a composite iron stabilizer consisting of HEDP and citric acid. Through a two-stage pH regulation mechanism, the pH of the residual acid was stabilized between 5 and 7, enabling direct discharge. Performance evaluation shows that the pad fluid of the buffered direct discharge acid plugging removal system achieves a calcium carbonate dissolution rate of 75.25%, while the treatment fluid exhibits dissolution rates of 34.70% for bentonite and 15.73%–20.91% for field cuttings, with an iron stabilization capacity of 175 mg/L. Its comprehensive performance is comparable to or better than that of conventional acid fluids. Following field application in multiple wells in the Bohai Oilfield, the system has achieved oil production increase ranging from 38% to 118 %. The flowback fluid can be directly routed into the production process without neutralization, demonstrating good plugging removal effectiveness and process compatibility. This technology provides a new solution for efficient and safe acidizing and plugging removal in offshore oilfields.

     

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