聚合物胶束钻井液在盐227-4HF井的应用

Study on Polymer Micelle Drilling Fluid and Its Application in Well 227-4HF

盐227-4HF井是胜利油田施工的一口非常规井,为避免在三开钻井过程中出现大段泥岩剥落、掉块,引发井下复杂情况,使用了一种聚合物胶束钻井液。该体系利用聚合物胶束的特殊性能,能显著提高钻井液的抑制性和对微裂缝、细微裂缝地层的封堵能力,确保易坍塌地层的井壁稳定。该井使用的聚合物胶束钻井液耐温达150℃,API滤失量仅为0.8 mL,150℃下的高温高压滤失量为8.4 mL,150℃和3.5 MPa条件下高温高压砂床侵入深度为4.2 cm。现场应用结果表明,该体系具有良好的流变性、抑制性和封堵能力,满足盐227区块非常规油气藏易坍塌地层的钻进需要。施工的盐227-4HF井平均井径扩大率为3.11%,水平段井径扩大率为2.97%,施工周期比设计缩短37.75 d。

A polymer micelle drilling fluid was used to drill the well Yan227-4HF, a nonconventional well drilled in Shengli Oilfield. The use of this drilling fluid is to prevent sloughing and caving of the shale formation penetrated which resulted in downhole troubles in previous drilling operation. The polymer micelle remarkably enhanced the inhibitive capacity of the drilling fluid, and micro fractures and fissures in the formation penetrated were effectively sealed off, stabilizing the unstable formations drilled. The polymer micelle can be used at 150 ℃, and the drilling fluid had API filtration rate of only 0.8 mL and HTHP filtration rate of 8.4 mL. In laboratory test, the depth penetrated by the polymer micelle drilling fluid into sand-bed was only 4.2 cm at 150 ℃ and 3.5 MPa. Field application showed that the polymer micelle drilling fluid had good rheology, inhibitive capacity and sealing capability. The well Yan227-4HF, drilled with the polymer micelle drilling fluid, had an average rate of hole enlargement of only 3.11%, with rate of hole enlargement in horizontal section being 2.97%. Operation time was shortened by 37.75 days compared with designed operation time.