高温低密度油基钻井液体系室内研究

Laboratory Study on High Temperature Low Density Oil Base Drilling Fluids

在高温深井中,为了保护低压油气层,合成一种新型有机土MZ,用以配制高温低密度油基钻井液体系。室内研究结果表明:有机土MZ的胶体率优于有机土A828、B500A和B38,MZ在柴油中胶体率可高达97.4%,高温热滚前后主要性能变化小,表明高温并没有破坏其聚结胶联的空间网状结构,具有较好的胶体稳定性和抗温性;MZ晶层间距为2.05 nm,季铵盐离子取代金属离子进入膨润土层间,使其晶层间距增大;MZ配制的高温低密度油基钻井液体系,热滚前后黏度变化不大,热滚后具有较高的切力,高温高压滤失量小于3 mL;MZ配制的钻井液能抗温220℃,抗50%盐水或15%泥岩钻屑的侵入污染,满足深井复杂地层钻井液技术需求。

A high temperature low density oil base drilling fluid was formulated with a newly developed organophilic clay MZ to protect low pressure reservoirs in high temperature deep wells.In laboratory experiment,the colloid fraction of MZ was greater than that of another three organophilic clays:A828,B500A and B38.The colloid fraction of MZ in diesel oil can be as high as 97.4%.The properties of the slurry made from MZ only change slightly before and after hot rolling at high temperatures,indicating that high temperature does not destroy the spatial network structure formed by the coalescing and crosslinking of the particles of MZ,and MZ has good colloidal stability and thermal stability.The crystal interlayer spacing of MZ is 2.05 nm.Substitution of quaternary ammonium ions for metal ions in the crystal layers of bentonite increases the crystal interlayer spacing.Testing on the high temperature low density oil base drilling fluid formulated with MZ showed that the viscosity o the drilling fluid changed only slightly before and after hot rolling.After hot rolling,the gel strengths of the drilling fluid increased,and the HTHP filter loss was less than 3 mL.Oil base drilling fluids formulated with MZ are resistant to high temperature to 220℃,contamination from invasion of 50%salt water or 15%shale cuttings,satisfying the needs of drilling deep wells penetrating complex formations.