一种多面锯齿金属颗粒作为骨架材料的高承压强度、高酸溶随钻堵漏钻井液

超深致密砂岩裂缝性气藏使用高密度全油基钻井液钻遇漏失复杂时,选用常规的防漏堵漏材料无法满足油相分散、酸溶和高承压等要求。为此,引入了油相分散、刚性高、酸溶率高的铝合金材料,该材料为密度1.60 g/cm~3的多面锯齿状铝合金颗粒(以下简称GYD),将泡沫态铝合金研磨成3~80目,较之于现用大理石架桥颗粒,GYD在油相中分散完全,莫氏硬度提高近2倍(介于5~6),酸溶率超过90%。按地层裂缝开度的1/2~2/3架桥规则,对以高密度全油基钻井液为基浆,GYD作为骨架颗粒,配合加入纤维类材料和可变性填充粒子的浆液进行高温高压动静态堵漏室内模拟评价。实验结果表明,GYD加量为8%时,堵漏钻井液封堵强度超过25 MPa,酸溶率达到65%,稳定性良好,48 h密度差小于0.03 g/cm~3。在塔里木盆地某井的现场试验效果表明,该井气藏埋深7 220 m,应用高密度油基钻井液日均漏失量约50 m~3,采用GYD防漏堵漏后钻进无漏失,顺利钻穿储层,较好地实现了钻进中地层缝内高流动阻力和高承压的"高刚性架桥+纤维成网+变形填充"封堵功能。

A new plugging-while-drilling fluid of high bearing strength and acid solubility with multifaceted zigzag metal particles as a skeleton material

When a high-density and oil-based drilling fluid is used in ultradeep tight sandstone fractured gas reservoirs, the conventional lost circulation materials could not meet the requirements of oil phase dispersion, acid solubility and high pressure in the case of complicated lost circulation. In this paper, the aluminum alloy material with the properties of oil phase dispersion, high rigidity and high acid solubility was introduced to solve the problem. This material is composed of multifaceted zigzag aluminum alloy particles (GYD) and its density is 1.60 g/cm3. The foamed aluminum alloy is ground into 3–80 meshes. Compared with the currently used marble bridge particles, GYD are dispersed completely in oil phase, its Mohs hardness is two times higher (up to 5.0–6.0) and acid solubility is over 90%. According to bridge rules of 1/2 – 2/3 opening degree of formation fractures, laboratory HTHP static and dynamic lost circulation simulation and evaluation were conducted on the slurry which is composed of high-density oil based drilling fluids (as the base slurry), GYD (as the skeleton particles), fiber material and variable filling particles. It is shown that the plugging pressure is over 25 MPa, acid solubility is 65%, the slurry is stable and the density difference (48 hrs.) is less than 0.03 g/cm3 when the dosage of GYD is 8%. This material was tested on site at a certain well in the piedmont zone of the Tarim Basin. The gas reservoir in this well is 7220 m deep. It is shown that the daily leakage was about 50 m3 when the high-density and oil-based drilling fluid was used. When the GYD drilling fluid was adopted, however, the reservoir is drilled smoothly without any leakage. And thus, the sealing function of "high-rigidity bridge + fiber network + deformable filling" is better exerted on the formation fractures with a high flow resistance and a high loading capacity.