海上致密砂岩气藏体积酸压技术研究

Volumetric acid fracturing technology of offshore tight sandstone gas reservoirs

海上致密砂岩气藏增产改造受多个因素限制,为促进海上致密砂岩气藏高效开发,开展了对海上致密砂岩气藏体积酸压技术的研究。针对砂岩储层酸压易出现的3点问题,对地质和工程提出6点要求。从储层岩性特征、脆性指数、应力特征和天然裂缝发育情况等方面对气田实例进行分析,总结出具备砂岩储层体积酸压的地质和工程条件。针对异常高温、高破裂压力、水锁伤害及水敏伤害严重等问题,研制出一套酸液体系,配方为:8%HCl+5%SA702+60%NaBr+1%WD-12+5%SA601+1.5%HJF-94+10%乙醇+1%SA1-1+1%WD-5B+1.5%SA1-7。酸预处理可有效降低储层破裂压力,实例应用中降低了9.5 MPa。采用6 mm纤维层内/缝内暂堵和1.5%纤维+0.8%小颗粒+1.2%大颗粒层间暂堵转向工艺进行体积酸压改造,单井增产了6.1倍,增产效果显著。该技术可为致密砂岩气藏开发提供理论依据和技术支持。

The stimulation of offshore tight sandstone gas reservoirs is influenced by several factors.In order to promote the efficient development of offshore tight sandstone gas reservoirs,volumetric acid fracturing technology of offshore tight sandstone gas reservoirs is studied.And then,considering 3 problems of acid fracturing in sandstone reservoirs,6 requirements for geology and engineering are put forward.Based on the analysis of reservoir lithological characteristics,brittleness index,stress characteristics and natural fracture development of the offshore gas field,the geological and engineering conditions of sandstone reservoir volume acid pressure are summarized.Aiming at the problems of abnormal high temperature,high breakdown pressure,water lock damage and serious water sensitivity damage,an acid liquid system is developed.The formula was 8%HCl+5%SA702+60%NaBr+1%WD-12+5%SA601+1.5%HJF+10%ethanol+1%SA1-1+1%WD-5B+1.5%SA1-7.Acid pretreatment can effectively reduce reservoir fracture pressure,and 9.5 MPa is reduced when applied.Volume acid fracturing is reformed by the interlayer temporary plugging steering technology using 1.5%fibre with the length of 6 mm+0.8%small particle+1.2%large particle.The single well increased production ratio was 7.1,and the yield increasing effect was remarkable.This technology can provide theoretical basis and technical support for the development of tight sandstone gas reservoirs.