哈萨克斯坦滨里海盆地巨厚盐膏层固井技术

哈萨克斯坦滨里海盆地Sagiski区块在盐间和盐下都有重大油气发现。但是,该区块巨厚盐膏层分布广泛,盐膏层井段容易产生溶蚀、蠕变,导致井眼不规则,从而在固井过程中固井顶替效率低,水泥浆不能完全充满环空,不能形成整体高强度的水泥环,使套管受到非均匀的外挤载荷(点载荷),致使套管发生变形甚至挤毁。此外,盐层的溶解会对水泥浆性能产生影响,使水泥浆稠化时间延长,影响水泥石强度的发展,严重影响固井成功率和固井质量。通过室内试验,优选出了FSAM-J优质抗盐降失水剂及配套的抗盐外加剂,配制了半饱和盐水水泥浆体系,其性能评价试验结果表明,该水泥浆体系具有流动性好、早期强度发展快、稠化过渡时间短等优点。应用该水泥浆体系,成功封固了Tasw-1井超过1 800 m的巨厚盐膏层,固井质量良好,为揭开盐下油气层提供了保障。

Cementing Technology Used in Huge Salt Bed in Pre-Caspian Sea Basin, Kazakstan

Remarkable hydrocarbon was identified in Sagiski block,Kazakstan.However,huge salt beds widely existing in the block can cause erode and creep resulting in irregular wellbore,which cause low mud displacement during cement operation.As a result,annulus cannot be filled with cement slurry completely and the strong cement sheath cannot be obtained,which result in heterogeneous loads causing string deformation even collapse.In addition,dissolution of salt bed might affect cement slurry properties and prolong wait on cement and development of cement strength,which affects cement quality and success ratio severely.Based on lab tests,a fluid loss agent named FSAM-J and associated salt-resistant additives have been developed.Evaluation tests show that the cement slurry has good flowability,rapid development of earlier strength,short wait on cement,etc.Huge salt beds over 1800m on well Tasw1 was cemented successfully using this cement slurry.The cement slurry is helpful to explore hydrocarbon zones beneath salt beds.