深孔绳索取心钻进用无固相防塌钻井液试验

Experimental study on solid-free anti-sloughing drilling fluid suitable for deep core drilling projects

为应对金刚石绳索取心钻进普遍发生的垮塌、造浆、钻杆内壁结泥皮等问题,完成了基于聚乙烯醇(PVA)为抑制剂的无固相防塌钻井液室内研究。通过泥页岩滚动回收试验、膨润土临界加量试验、泥球浸泡试验以及电动电位测试等对比了常用抑制剂的抑制效果;通过配伍性试验确定了增黏剂及降失水剂的种类和加量;对比了不同种类的污染物对所获配方钻井液综合性能的影响。结果表明,相比于NaCl、KCl等常规无机盐抑制剂,聚乙烯醇具有较强的抑制性,且抑制性与聚合度呈正相关;黄原胶(XC)、磺化褐煤树脂(SPNH)、磺化沥青(FT-1)可用作配制该钻井液的增黏提切剂和降失水剂;该配方钻井液可抗35%NaCl、4%CaCl_(2)以及12%钙土的污染,能满足110℃温度范围内的使用要求,可在3000 m深度范围内的强造浆地层、破碎地层、盐膏层等复杂地层中使用。

To deal with the problems of wellbore collapse,mud making and mud lining in drilling strings,a solid-free anti-collapse drilling fluid with polyvinyl alcohol as inhibitor was developed.The inhibition effect of commonly used inhibitors was studied by shale hot rolling recovery test,critical addition of bentonite test,and mud boulder soaking test.The types and dosage of viscosifiers and water loss reducers were determined by compatibility test,and the influence of different pollutants on the comprehensive properties of the formulated drilling fluid were compared.Experimental results showed that compared with the conventional inorganic salt such as NaCl and KCl,polyvinyl alcohol had a stronger inhibition effect which was positively correlated with polymerization degree.XC,SPNH and FT-1 could be used as viscosifier and water loss reducers to prepare the drilling fluid,respectively.The performance of formula drilling fluid under the pollution of 35%NaCl,4%CaCl_(2) and 12%calcium bentonite can be stable in the temperature of 110℃,indicating that the prepared drilling fluid can be used in the strong mud making strata,fractured strata,salt bed and other complex strata in the depth of 3000 m.