LG地区超深井固井工艺技术

LG地区气井的井筒条件复杂，大尺寸套管固井、多套压力体系的长封固段固井、高压气层的油层套管固井难度极大。为解决以上难题，通过优化固井施工程序，进而从水泥浆的体系、套管的安全下入、附件的优选与应用、现场施工技术措施等方面进行了研究，摸索出339.7 mm技术套管采用插入法或双胶塞法固井；244.5 mm单级长封固段固井，用合理的浆柱、两凝防漏早强水泥浆达到了封隔地层、防止气窜的目的；177.8 mm尾管固井，其须家河组气〖JP2〗层显示相当活跃，采用两凝或三凝的抗硫、早强、直角稠化、防气窜、防漏失的双密度水泥浆体系保证了油气层的封固质量；127.0 mm尾管段含高压气层，采用抗高温早强、复合多功能纤维的加砂抗硫水泥浆成功地实现了高压气层的封隔；177.8 mm套管回接固井，采用低失水、早强、微膨胀的水泥浆保证了回接固井质量。

Cementing technology used in the ultra-deep wells at the LG area

The gas wells at the LG area have very complex wellbore conditions for cementing, such as large size casing cementing, long interval cementing at formations with multiple pressure systems, and production casing cementing at high-pressure gas formations, etc. In order to find solutions for those difficulties, investigation has been made on the optimization of cementing operation procedures, formulation and selection of cement slurry systems, safe casing running, selection and operation of cementing accessories, and field measures. It is concluded that: a. insertion method or double plug cementing method can be used for the 339.9 mm-diameter intermediate casing; b. reasonable slurry column and double-set loss-free rapid-hardening cement slurry can be used for the single-stage long-interval cementing of 244.5 mm-diameter casing to realize both formation isolation and gas channeling prevention; c. the double-density cementing slurry which is double- or triple-setting, H_2S-resistant, rapid-hardening, right-angle thickening, and which can prevent gas channeling and lost circulation, can be used for the cementing of 177.8 mm-diameter liner where there is active gas show in the Xujiahe formation, to ensure good plugging at payzones; d. while the sand-laden and H_2S-resistant cement slurry featured with high-temperature, and rapid-hardening, compound multifunction fibers can be used for the 127.0 mm-diameter liner to successfully isolate the high-pressure gas zones; and e. the low-water-loss, rapid-hardening, micro-expansion cement slurry can be used for the tie-back of 177.8 mm-diameter casing to ensure good tie-back quality.