新型水基聚合醇钻井液性能评价

Lab Tests on A Novel Water-Based Polyglycol Drilling Fluid

由于原位天然气水合物极度不稳定,在钻探和取心过程中易发生分解,进而导致一系列意想不到的钻井事故。因此,在水合物地层钻井首先要防止水合物大量分解,而要达到此目的,科学合理地选择钻井液则是重要举措之一。针对海底天然气水合物地层及其钻井的特性,给出了钻进海底天然气水合物地层时钻井液体系的设计原则,根据此原则在充分考虑现有常用聚合醇钻井液体系特点的基础上,设计了一种适合海底天然气水合物地层钻井的新型聚合醇钻井液,并对其页岩水化抑制性、低温流变性和水合物生成抑制性(动态和静态)进行了评价。结果表明,该钻井液体系能够有效抑制页岩水化分解和防止水合物在循环管路内重新生成,且在低温条件下具有良好的流变性能,能够有效保持井壁稳定,清洁和冷却孔底,是一种比较适合海底天然气水合物地层钻探的钻井液体系。

In situ hydrate is unstable and dissociates easily during drilling or coring which may result in a series of drilling accidents. Therefore, it is important to prevent hydrate dissociation during gas hydrate drilling, and a properly designed drilling fluid is one of the most important measures. Considering the properties of hydrate formation, the designing principle of drilling fluid was provided. Based on this, a new polyalcohol drilling fluid for oceanic hydrate formations was formulated. The performance of this drilling fluid was evaluated by shale hydration inhibiting test, low temperature rheological property test, and gas hydrate formation inhibiting experiment （both static and dynamic）. The results show that the developed drilling fluid system has good rheological property, can maintain the wellbore stability, can clean and cool the bottom hole, which is a very good drilling fluid for oceanic hydrate formations.