用多功能钻井液设计超低密度矿渣水泥浆

本文针对陕甘宁盆地中部低渗透天然气田低压易漏地层二级固井中存在的问题，利用高炉矿渣、漂珠的潜在活性及比重较小的特点，结合多功能钻井液固井技术的优点，用多功能钻井液设计超低密度（１２０ｇ／ｃｍ３～１４０ｇ／ｃｍ３）矿渣水泥浆。用该水泥浆为领浆和纯Ｇ级水泥浆为尾浆对天然气井进行一次性注水泥固井，替代分级固井技术。室内研究结果表明：超低密度矿渣钻井液固化液中激活剂可以扩散到滤饼和残留的多功能钻井液中，使套管、水泥石和地层三者之间达到完整的胶结，使地层封隔效果良好，水泥石抗压强度高，水泥浆流变性好，体系稳定，稠化时间满足现场施工要求，并解决了分级固井技术中存在的固井质量问题。

PREPARATION OF FURNACE SLAG CEMENT SLURRY WITH ULTRA-LOW DENSITY USING MULTI-FUNCTIONAL DRILLING FLUID

According to the actual problems existed in two-stage cementing operations in low pressure leaking formations of low permeability gas field,using blast furnace slag(BFS),floating beads and combining advantages of universal (drilling) fluid (UF) cementing technique,slag cement slurry with ultra-low density of 1.20-1.40g/cm 3 is designed. The paper introduces one-trip cementing technique using this (ultra-low density slag cement) slurry as lead slurry and pure G slurry as tail slurry to substitute for fractional cementing technique. Laboratory research results show that activation agents in the curing fluid for slag drilling fluid with ultra-low density can diffuse into filter cake and residual UF, Thus, casing,cementstone and formation will obtain complete bonding,good formation isolation result and high compressive strength.Slag cement slurry has good rheology,systematic stability and satisfactory thickening time that can meet the requirements of field operations and can solve the cementing quality problems existed in fractional cementing technique.