抗高温钻井液增黏剂的研制及应用

以N-乙烯基己内酰胺为温敏性单体,对苯乙烯磺酸钠为亲水性单体,N,N-亚甲基双丙烯酰胺为交联剂,采用自由基胶束乳液聚合法研制出了一种抗高温钻井液聚合物增黏剂。通过正交试验确定了最佳合成条件,借助元素分析、凝胶色谱分析、热重分析和急性生物毒性实验分别表征了该增黏剂的元素组成、相对分子质量、热稳定性和EC50值,研究了其在水基钻井液中的增黏性能及温敏特性,探讨了增黏机理,优化出了一套适用于环渤海湾地区的可排放水基低密度抗高温钻井液体系,并进行了现场试验。结果表明:该聚合物增黏剂具有优异的增黏性能、热稳定性及温敏特性,在淡水基浆和盐水基浆中经220℃、16h老化后的表观黏度保持率分别为90.81%和95.95%,EC50值为15.529×104 mg/L,满足可排放海水基钻井液技术要求;新研制出的聚合物增黏剂在环渤海湾地区冀东油田深部潜山储层现场的成功应用表明该处理剂能够在深部超高温地层、低膨润土含量及低密度钻井液体系中有效发挥增黏作用,同时也有效地解决了以大量消耗常规磺酸盐共聚物等钻井液处理剂为代价的钻井液日常性能维护问题。

Synthesis and field application of high temperature resistant viscosifying agent for drilling fluid

A polymer viscosifying agent with ultra-high temperature resistant ability was synthetized by the method of micellar free radical emulsion polymerization which using N-vinyl caprolactam as temperature sensitive monomer, sodium styrene sulfonate as hydrophilic monomer and N,N-methylene bis acrylamide as crosslinking agent. In order to research its viscosity and temperature sensitivity in low density drilling fluid, elemental analysis, gel permeation chromatography analysis, TG-DTA analysis and acute toxicity experiment were carried to indicate the elemental composition, molecular weight, thermal stability and EC₅₀ value of this viscosifying agent at the optimum synthetic conditions determined by orthogonal test. Based on the study of the thickening mechanism, a high temperature resistant emitted sea water-based drilling fluid with low density suitable for Bohai Bay region was built and flied test was also carried. The results showed that: this polymer viscosifying agent had excellent ultra-high temperature resistance and salt resistance viscosifying property, thermal stability and thermo sensitive characteristics. The apparent viscosity retention rate after aging were 90.81% and 95.95% respectively and the EC₅₀ value was 15.529×10⁴ mg/L at 220℃,after 16h in both fresh water based mud and salt water based mud which can satisfy the requirement of the emitted sea water-based drilling fluid technology. Field application shows that this new polymer viscosifying agent could play an effective viscosifying role even though at harsh conditions such as ultra-high temperature and low density drilling fluid system which decreasing daily performance maintenance problems at the expense of the large consumption of fluid additive including conventional sulfonate copolymer.