超深碳酸盐岩水平井水力喷射定点深度酸化压裂技术

Fixed-Point Acid Fracturing Technology in the Ultra-Deep Carbonate Horizontal Well

埋深超过6 000 m的碳酸盐岩长裸眼水平井,常规笼统酸化压裂技术无法控制裂缝位置,浅、中深裸眼井分段酸化压裂技术也不适用。针对该问题,研发了超深井新型水力喷射定点酸化压裂技术。该技术通过2趟管柱实现定点深度酸化压裂:第1趟管柱下入喷射工具至目标位置,射孔并压开裂缝,产生应力薄弱区;第2趟管柱优化下入深度和压裂液类型,消除喷嘴节流压差和部分管柱摩阻,实现大排量酸化压裂施工,最高施工排量可达到10. 0 m^3/min,裂缝沿薄弱区继续延伸,完成对目标缝洞体的深穿透沟通。定点射孔起裂后,相比起裂前裂缝延伸阶段施工压力降低5. 0~14. 0 MPa,有效保证了后续主裂缝仍然沿起裂点扩展。采用加重压裂液作为射孔液,其密度和对应井段钻井液密度接近,既能降低射孔阶段的施工压力,又能消除起下管柱过程中的井控风险。在塔里木盆地阿克库勒凸起P5超深水平井应用该技术,实现了对目标储集体的准确沟通,酸化压裂后日产油达到107 t/d。该技术为超深井定点高效改造提供了有益的探索。

The fracture initiation cannot be controlled by conventional acid fracturing for the carbonate open-hole horizontal well with long lateral section and a buried depth of more than 6000 m. The multi-stage acid fracturing for shallow,medium and deep open-hole well is also inapplicable to this case. A new fixed-point acid fracturing technology with hydraulic jet was developed to improve the acid fracturing performance. The fixed-point acid fracturing was realized by this new technology with dual-trip string running. In the first-trip string running,the hydraulic jet tool is loaded to the target position and the well is perforated and fractured to create a weak stress zone. In the second-trip string running,the depth and fracturing fluid are optimized to eliminate the nozzle throttling pressure difference and partial string friction. Large pumping rate acid fracturing is achieved and the maximum operation displacement can reach 10.0 m^3/min. The fractures continue to propagate along the weak zone to realize large-scale penetration of the fracture-cavity body. After the fracture initiation in the fixed-point,the operating pressure is reduced by 5.0 ~ 14.0 MPa than that without fracture initiation,which effectively ensures that the subsequent main fracture still propagate along the fracture initiation point. The weighted fracturing fluid is adopted as the perforating fluid and the corresponding density is close to that of the drilling fluid in the corresponding well section. The weighted perforating fluid cannot only reduce the operating pressure during perforating operation,but also eliminate the well-control risk during string running. This technology was applied in the Ultra-deep horizontal well P5 in the Akekule Uplift of Tarim Basin,which efficiently connected the target reservoir. The daily oil production is up to 107 t/d after acid fracturing treatment. This technology could provide a favorable exploration for the fixed-point efficient stimulation of ultra-deep well.