风险探井花深1x井深部破碎带地层钻井液技术

花深1x井是中国石油集团部署在福山油田的最大井深大位移风险探井，设计井深为5713.16 m，钻探目的为预探断鼻高部位流三段含油气情况及预测石油储量。该井位于北部湾盆地福山凹陷，其古近系流沙港组地层复杂，存在断层和厚达1300 m破碎带，泥岩硬脆性强，微裂缝与层理发育，水敏性极强，极易失稳垮塌；地层温度在180℃以上，对钻井液抗高温性能要求高。设计最大位移为3208 m，大位移井眼对钻井液流变性、抑制性和润滑性要求更高。在钻探过程中，因对地层岩性掌握不够，于四开大斜度段出现严重垮塌，造成3次侧钻，因此在第3次侧钻的井眼（井眼Ⅳ）使用有机盐与无机盐复配的复合盐水钻井液，该钻井液具有强抑制、强封堵和抗高温性，解决了流沙港组流二段与流三段交界面破碎带地层垮塌难题，保证了该井四开各项工序安全施工。 

Drilling Fluid Technology for Drilling Deep Broken Formations in the Exploratory Well Huashen-1x

Well Huashen-1x, designed to drill to 5713.16 m, is the deepest exploratory extended-reach well deployed by CNPC in Fushan oilfield, Hainan. This well was drilled to ascertain the reservoir engineering data of the member Liu-3 located on the top of a fault nose structure. This well is located in the Fushan depression in the Beibuwan Basin, and the formation at the deep part of the well is the so-called Liushagang formation of the Paleogene System, which is complex. Faulting, broken belt of 1300 m in length, hard and brittle mudstone, developed micro fractures and beddings, strong water sensitivity of the formation rocks which are very instable and easy to slough, and high well temperature of up to 180℃, are all challenges to drilling fluid operations. The maximum displacement of the well designed was 3208 m. Extended-reach well places higher requirements on the rheology, inhibitive capacity and lubricity of the drilling fluid. During drilling, lack of understanding of the lithology of the formations resulted in severe sloughing in the highly deviated fourth interval and three times of sidetracking in this interval. In the third sidetracking, a drilling fluid formulated with organic salts and inorganic salts was used. This compounded salt drilling fluid, with its strong inhibitive capacity, good plugging capacity and high temperature resistance, resolved the borehole instability problems encountered in the broken belt between the Liu-2 member and Liu-3 member of the Liushagang formation, ensuring safe drilling and other operations in the fourth interval.