渝西大足区块超深超长页岩气水平井钻井技术

为了解决渝西大足区块页岩气超深、超长水平井存在井眼轨迹控制难度大、机械转速低、钻柱振动较大且井温偏高等技术难点，优化了水平段铂金靶体的储层选择，将水平段箱体位置选取于五峰组底界以上5~8 m，依据断层倾角进行剖面设计；优化井身结构设计封隔易漏、易垮塌地层；利用高造斜率ATC旋转导向工具，匹配地层优化钻头选型，降低轨迹控制难度和提高钻进速度；采取分段优化钻具组合和钻井参数，优选油基钻井液确保井壁稳定性，降低钻井风险；利用慢放缓压减振法降低钻具振动和循环降温措施解决井温偏高难题。现场应用顺利完成了该区块多口超长超深水平井的施工，形成了渝西大足区块超深、超长页岩气水平井关键钻井技术，为该区块积累了超深超长页岩气水平井施工经验。

Drilling technology of ultra-deep ultra-long shale gas horizontal wells in Dazu,West Chongqing

To deal with the technical challenges faced by the ultra-deep ultra-long shale gas horizontal drilling in the Dazu block of West Chongqing, such as high difficulty in well trajectory control, intensive drill vibration, and high downhole temperature, the reservoir selection for the horizontal well platinum target was optimized, the box range of the horizontal well was set as 5-8 m above the base of the Wufeng Formation, and the profile was designed in accordance with the fault dip angle. The casing program was improved to isolate layers prone to lost circulation or collapse. Moreover, the ATC rotary steerable system with high build-up rates, together with formation-adapted bits, was adopted to reduce difficulties in trajectory control and improve the penetration rate. The bottomhole assembly and drilling parameters were optimized in an interval-wise manner and the oil-based drilling fluid system was selected, in an attempt to ensure well stability and reduce drilling risks. At last, the slow-slacking approach was used to reduce the drill string vibration and extra cooling was deployed for drilling fluid circulation to deal with high formation temperature. Field applications of these techniques help to complete well construction of multiple ultra-deep ultra-long horizontal wells in this block and accumulate operation experience for ultra-deep ultra-long shale gas horizontal drilling. The key technology for ultra-deep ultra-long shale gas horizontal drilling in the Dazu block of West Chongqing has been formed.