长封固段低密度水泥浆固井技术

晋古13井是一口井深为4988.56 m的奥陶系潜山预探井,三开完钻后,要求在2780～4987.5 m井段下入φ 177.8 mm尾管进行固井,重点封固好3886～4366 m的油层井段.由于本井存在盐膏层、煤层及溶孔和裂缝型地层,钻井过程中曾发生垮塌和漏失,且裸眼段地层井径大而不规则,套管重叠段环空间隙小,水泥封固段顶底温差大等客观因素,需一次封固水泥2200多米,存在许多困难和风险.通过研制低密度水泥浆体系,优选G309、G301、GH-9和ZW-1控制水泥浆性能,采用适当的固井技术措施,保证了施工的顺利,固井质量达到了优质,为长封固段、高温井、复杂井的尾管固井施工积累了成功的经验.

Long production interval cementing in Jingu13 well using a low density slurry

Jingu13 well is a preliminary prospecting well of 4988. 56 m located in Buried Hill of Ordovician System. When the third interval was drilled, the section from 2780 m to 4987. 5 m was required to run (?) 177. 8 mm casings, and the productive interval of 3886-4366 m should be effectively cemented especially. For the presence of salt-gypsum layer, coal bed and vugular pore- fracture formation, hole collapse and lost circulation were experienced in previous drilling. What's more, facts such as irregular and long radius of barefoot interval, small annulus in casing overlapped section and large temperature difference from top to bottom introduce difficulties and risks to perform single-stage cementing of productive interval as long as 2200+ m. A low density cement slurry was developed using G309, G301, GH-9 and ZW-1 to condition the slurry properties. Coupled with proper cementing measures, on-situ operation was successful with high quality.