土库曼斯坦尤拉屯地区复杂盐膏层钻井液技术

土库曼斯坦尤拉屯地区高压盐水盐膏层钻井过程中钻井液性能调控难度大，井漏问题突出。结合高压盐水盐膏层地质工程特征，通过分析高密度钻井液在高温及高钙污染环境下性能调控及防漏堵漏技术难点，开展了高密度钻井液体系和防漏堵漏剂配方及应用技术研究。基于现有的高密度饱和盐水体系，通过高钙污染抑制剂的引入和配套处理剂的优选，形成抗高温高钙的高密度钻井液。室内评价和现场应用表明，该体系抗温可达140℃，抗钙可达40 000 mg/L。解决了大段膏盐地层条件下的钙污染问题。应用降低循环压耗的高密度钻井液技术和随钻防漏技术相结合，使用高浓度桥塞堵漏技术较好地解决了井漏及安全密度窗口窄的难题，应用效果显著。 

Drilling Fluid Technology for Complex Salt-Gypsum Interbeds Drilling in Yolot,Turkmenistan

Drilling operations in the Yolot area, Turkmenistan have encountered two problems, difficulties in controlling the properties of the drilling fluid because of high pressure formation water invasion and salt/gypsum interbeds, and mud losses. Studies have been conducted on high density drilling fluid formulations and mud loss control and prevention based on the geological and engineering characteristics of the high pressure saltwater zones and the salt/gypsum interbeds. Analyses were conducted on the difficulties in maintaining and controlling the properties of the drilling fluid as well as controlling and preventing mud losses at high drilling fluid densities, high temperatures and high calcium contamination. A high density saturated saltwater base drilling fluid was modified by introducing calcium-resistant shale inhibitors and other selected additives, giving birth to a high temperature high density drilling fluid containing high concentrations of calcium ions. Laboratory study and field practice showed that the modified drilling fluid was able to resist the effects of high temperatures to 140 ℃ and calcium contamination to 40,000 mg/L. Use this drilling fluid, calcium contamination from long section of salt/gypsum interbeds was successfully resolved. By reducing circulation pressure loss of the high density drilling fluid and using the techniques of mud loss control while drilling, combined with high concentration bridging lost circulation material slurries, drilling problems such as mud losses and narrow safe drilling window were satisfactorily resolved.