长庆陕224区块储气库井大尺寸套管固井技术

长庆陕224区块地层不稳定,本溪组泥岩段及煤层易出现坍塌,钻井液密度高,接近1.60 g/cm3,技术套管均采用φ244.5 mm大尺寸尾管固井,环空间隙大,冲洗顶替困难,影响水泥石胶结质量。同时储气库井单井注采气量大,工作压力高,长期的注采交变应力作用于水泥环,水泥环的密封完整性不易保证,易出现环空窜流、带压等问题。为此,开发优化了高密度高效冲洗隔离液体系以及韧性水泥浆体系。并在陕224区块靖平22-4-2井φ244.5 mm尾管固井中得到成功应用,固井质量合格率为95.46%,优质率为79.05%,后期注采施工顺利。

Large Size Well Cementing for Underground Gas Storage in Block Shaan224 Changqing

The Benxi Formation in the Block 224 in Changqing Oilfield is mainly unstable mudstones and coal beds which always collapsed during drilling with mud density of nearly 1.6 g/cm3. The liner string commonly used had a diameter of 244.5 mm, making well cementing difficult because of large annular space and difficulty in flushing and displacing, and cementing quality of the set cementing poor. Meanwhile, the volumes of gases injected into and produced from a single gas storage well were huge, causing the cement sheath to be broken by the action of cyclical stresses, and hence annular channeling and pressure anomaly. To solve these problems, a high performance high density flushing spacing fluid and a cement slurry with enhanced toughness were developed and were applied successfully in the cementing of the φ244.5 mm liner in the Well Jingping22-4-2 in Block Shaan224, with 95.46% of the cementing job acceptable and 79.05% high quality. Subsequent injection and production of gases were operated without a hitch.