摘要
为了实现东濮凹陷深层断块低渗油气资源的低成本开发,采用水平井开发和简化井身结构成为必然的选择。但是作为开发中后期的老油田,地层压力系统紊乱,简化井身结构后,同一裸眼段内高低压共存,易导致滑动钻进压差卡钻和井壁失稳;同时沙一至沙三段泥页岩发育,长裸眼段内井壁坍塌、掉块问题突出。为此,应用横观各向同性模型,考虑水化时间对强度的影响,兼顾井下安全和钻井投资,确定出技术套管的合理下深;优选聚胺抑制剂和梳形聚合物降滤失剂,应用油基钻井液,提高泥页岩地层井壁稳定能力;引入无土相烷基糖苷钻井液,提高润滑性,降低钻进摩阻;应用降压耗钻具组合,解决小井眼清除岩屑问题;设计小弯角螺杆配合欠尺寸稳定器的水平段提速钻具组合,提高机械钻速,降低钻井周期,规避坍塌周期风险,提高复合钻进比例,降低定向滑动压差卡钻风险。7口井的现场应用效果表明,钻井周期缩短了30.95%、卡钻事故降至0次,实现了东濮凹陷大压差泥页岩长裸眼斜井段安全钻井。
Horizontal wells and simplified casing program are the only choice to economically exploit low- permeability and deep-buried fault-block reservoir of Dongpu Sag. As an oilfield after 40 years develop- ment, the formation pressure system is very complex because of long-term waterflooding. After adopting simplified well structure, strata with different pressure coefficient would be exposed in one open hole, which could cause drill pipe sticking during slide drilling and borehole instability. At the same time, mud- stone and shale commonly exist in Shaximiao Formation, which may cause severe borehole collapses. To solve these problems, by means of transversely isotropic model and shale hydration effect, optimum casing depth was carefully designed to ensure safety and cut cost. Water-based drilling fluid added with polyamine inhibitor and comb-shape polymer filtrate reducer, and oil-based drilling fluid was used to keep borehole stability. Clay-free alkyl polyglucoside drilling fluid was used in horizontal section of sandstone strata to reduce friction. Bottom-hole-assembly with small bent angle PDM and under-gauge stabilizer were de- signed for long-horizontal sections, which could increase penetration rate to avoid shale collapse, and also could decrease sliding drilling time to avoid differential pressure sticking. The results of safe drilling tech- nology used in 7 wells show that the average drilling duration cuts down by 30.95% and no drill pipe stick- ing accident occurs.
出处
《地质科技情报》
CAS
CSCD
北大核心
2016年第1期218-222,共5页
Geological Science and Technology Information
基金
中国石化科研项目"中原油田深层水平井关键技术研究"(JP12005)
关键词
泥页岩
井壁稳定性
压差卡钻
井身结构优化
钻井液
钻具组合
mudstone and shale
borehole stability
differential pressure sticking
well structure optimiza-tion
drilling fluid
bottom hole assembly
