川西超深海相碳酸盐岩超高压分段酸压技术实践

Practice of Ultra-high-pressure Staged Acid Fracturing in Western Sichuan Ultra-deep Marine Carbonate

PZ103H井是川西海相碳酸盐岩一口典型超深勘探评价井,埋深达6 071 m,储层温度155℃。针对储层超深致密可能压不开的难题,设计时尽可能替酸到产层,配套140 MPa井口及相应配套高压管汇;针对压不开震荡试挤时酸液长时间浸泡腐蚀油管的风险,优选了高温酸液缓蚀剂配方,室内评价在180℃、24 h条件下对P110SS材质油管腐蚀仅21.4 g/(m_2·h),远小于100 g/(m_2·h)的行业标准要求;针对储层段长83 m,均匀布酸难度大,设计了"机械式封隔器(RTTS)+液压式封隔器(Y241)"组合工具进行分段酸压。同时,为实现深度酸压充分改造,设计了"胶凝酸、交联酸、压裂液"三种不同液体交替注入的大规模酸压改造,两段总液量达2 132 m_3。现场施工表明,设计的组合工具满足了分段及大规模超高压施工,压后在油压14.2 MPa下获得天然气产量12.65×104m_3/d,水产量276 m_3/d,充分评价了储层。形成的以高温缓蚀酸液、超高压施工、"机械式封隔器(RTTS)+液压式封隔器(Y241)"工具组合、多级交替注入为一体的分段酸压技术,为类似超深高含硫储层提供了借鉴。

Well PZ103H is a typical ultra-deep well of marine carbonate in western Sichuan,with a buried depth of 6071m and temperature of 155℃.To solve the problem that the ultra-deep and tight reservoir may not be fractured,the design is to replace acid to the production layer as much as possible,and use 140 MPa wellhead and corresponding high pressure manifold.In view of the risk of acid corroding tube during shock extrusion test,the formulation of high-temperature corrosion inhibitor was optimized.The corrosion of P110SS tube was only 21.4 g/(m 2·h),far less than the industrial standard requirement of 100 g/(m 2·h)under the condition of 180℃and 24 h in the laboratory.The combination tool of“mechanical packer(RTTS)+hydraulic packer(Y241)”was designed to carry out staged acid fracturing because the reservoir section was 83m and it was difficult to distribute acid evenly.At the same time,in order to achieve deep acid fracturing,a large-scale acid fracturing with a total liquid volume of 2132 m 3 in two stages was designed by alternating injection of three liquids of“gelling acid,crosslinked acid and fracturing fluid”.Field application shows that the designed combination tool meets the requirements of staged and large-scale ultra-high pressure operation.After acid fracturing,the gas production is 12.65×104 m 3/d and water production is 276 m 3/d under tubing pressure of 14.2 MPa,which fully evaluates the reservoir.Formed by the combination of high temperature corrosion inhibition acid,ultra-high pressure construction,“mechanical packer(RTTS)+hydraulic packer(Y241)”tools and multi-stage alternating injection,the technology of staged acid pressing provides reference for similar ultra-deep and high-sulfur reservoirs.