DYS4侧钻水平井完钻井深5587 m,垂深4186.34 m,水平位移1607.72 m,具有油基钻井液固相含量高、井壁和套管壁清洗困难、封固段长(5584.49 m)、顶底部温差大(110℃)、顶替效率难以保证等诸多固井难点.通过优化固井方案,优选了双凝双密度水泥浆体系和驱油型隔离液体系,且采用了油基泥饼固化剂,制定了配套防气窜、井眼清洁等固井技术措施.现场应用结果表明,该井固井一、二界面胶结质量优质,有效封固了页岩气水平段,达到了预期目的,为后续大型分段体积压裂奠定了良好的井筒基础,同时也可为油基钻井液条件下的水平井固井提供借鉴和参考.

T Y1侧钻水平井两次发生失返性漏失,且下套管后期即发生漏失,后虽基本建立循环,但循环排量仅约为1.4m3/min,远达不到固井设计施工排量1.7m3/min-1.8m3/min的要求,并且还存在油基钻井液固相含量高、井壁和套管壁清洗困难、封固段长、顶底部温差大、顶替效率难以保证等诸多固井难点.通过采用油基泥饼固化剂,制定配套防漏、防气窜,优化固井方案等技术措施,该井水平段固井一、二界面胶结质量优质,有效封固了页岩气水平段,为后续大型分段体积压裂奠定了良好的井筒基础.实践经验和技术对策值得同行借鉴.

川东南焦石坝地区海相页岩气井具有地表和地下地质条件复杂、井壁稳定困难、井眼轨迹要求高、造斜段及水平段钻进困难、长水平段固井难度大等特点及难点,经过攻关研究,配套形成了三开井身结构、浅层气安全钻井、气体钻井、复合钻井、水平井钻井、油基钻井液、弹塑性水泥浆体系、钻头选型及参数优化以及地质跟踪导向等钻井技术,实现了该地区勘探井的优快钻井,有效支撑了勘探工作.

The purpose of this study is to improve the cementing quality of shale gas well by mud cake solidification, as well as to provide the better annular isolation for its hydraulic fracturing development. Based on the self-established experimental method and API RP 10, the effects of mud cake solidifiers on the shear strength at cement-interlayer interface (SSCFI) were evaluated. After curing for 3, 7, 15 and 30 days, SSCFI was remarkably improved by 629.03%, 222.37%, 241.43% and 273.33%, respectively, compared with the original technology. Moreover, the compatibility among the mud cake solidifier, cement slurry, drilling fluid and prepad fluid meets the safety requirements for cementing operation. An application example in a shale gas well (Yuanye HF-1) was also presented. The high quality ratio of cementing quality is 93.49% of the whole well section, while the unqualified ratio of adjacent well (Yuanba 9) is 84.46%. Moreover, the cementing quality of six gas-bearing reservoirs is high. This paper also discussed the mechanism of mud cake solidification. The reactions among H3AlO42- and H3SiO4- from alkali-dissolved reaction, Na+ and H3SiO4- in the mud cake solidifiers, and Ca2+ and OH- from cement slurry form the natrolite and calcium silicate hydrate (C-S-H) with different silicate-calcium ratio. Based on these, SSCFI and cementing quality were improved.

<正>[中国石化报中心]入汛以来,我国多地遭受暴雨、台风袭击,部分地区发生山洪、泥石流、滑坡等灾害。中国石化驻各地企业紧急启动应急预案,周密部署安全措施,加强汛期灾害防范应对,确保员工生命安全、生产平稳运行,千方百计保证救灾抢险油料供应。

The mechanism that hydration ions in the mud to cement slurry(MTC) cementing fluid can diffuse and migrate into the mud cake from multifunctional drilling fluid has been well researched,while it still remains unclear at present why hydration ions in the oil-well cement can not diffuse into the mud cake from multifunctional drilling fluid.Herein,we examined differences in ion compositions of the oil-well cement and the MTC cementing fluid by means of ion chromatography,atomic absorption spectrophotometer and X-ray diffraction,and investigated thoroughly the hindering mechanism that prevent hydration ions in the oil-well cement from diffusing and migrating into the mud cake from multifunctional drilling fluid.The result indicated that Ca2+ in the oil-well cement has a mass fraction much higher than that in the MTC cementing fluid and can form CaCO3,CaSO4 and Ca(OH)2 at the interface between the oil-well cement and the mud cake from multifunctional drilling fluid.The mass fraction of Na+ in the MTC cementing fluid,however,is much higher than that in the oil-well cement,moreover,Na+ can change the ζ potential on the surface of active particles in the mud cake and destroy the water film formed on the surface of organic additives from drilling fluid,which are the major reasons that make hydration ions in the MTC cementing fluid capable of diffusing and migrating into the mud cake from multifunctional drilling fluid.Whereas,the CaCO3,CaSO4 and Ca(OH)2 formed at the interface of the oil-well cement and the mud cake from multifunctional drilling fluid may precipitate and block apertures,which is attributed to the main hindering mechanism that prevents hydration ions in the oil-well cement from diffusing and migrating into the mud cake from multifunctional drilling fluid.

To improve the cementing quality of shale gas wells ,mud cake curing agent was applied in the well cementing of φ244.5 mm casing in Well Yuanye HF 1 .Based on the drilling fluid and cement slur-ry used in Well Yuanye HF 1 and API specification 10 ,the effects of mud cake curing agents (GJ Ⅰ and GJ Ⅱ) on bond strength at cement-formation interface was evaluated by the self-established evaluation method .The evaluation results showed that when the curing time was 3 ,7 ,15 and 30 days ,compared with cementing without curing agent ,the bond strength of cement-formation interface with mud cake curing a-gent remarkably increased by 629 .03% ,222.37% ,241.43% and 273.33% ,respectively .72 hours after ce-menting ,acoustic amplitude variable density logging (CBL/VDL )was carried out .The logging results showed that the proportion of cementing section with relative acoustic amplitude of less than 15% is 93 .49% ,indicating good cementing quality .The study showed that mud cake curing agent could greatly im-prove the bond strength at cement-formation interface and thus the cementing quality of shale gas wells .