针对大斜度射孔井水力压裂中裂缝形态复杂,易造成压裂加砂难的问题,通过物理模拟实验研究了大斜度射孔井中水力裂缝的起裂、转向及扩展形态。研究表明,不同水平应力差条件下,井斜角、方位角和射孔相位角的变化会导致不同的水力裂缝形态:当井斜角小于20°或大于80°、方位角小于30°、水平应力差大于3 MPa、射孔相位角为60°时,两翼裂缝平滑扩展,裂缝形态简单;当井斜角为40°~60°、方位角大于30°、水平应力差小于3 MPa、射孔相位角为90°时,裂缝的扭曲程度大,次级裂缝多,裂缝形态复杂。上述认识与冀东油田滩海403X1区块现场压裂统计结果相吻合,可为提高大斜度井压裂成功率提供参考。
In highly deviated wells, the hydraulic fracture geometry is complex and it is always difficult to add proppant. In this paper, physical simulations of hydraulic fracturing were conducted to study the initiation, reorientation and propagation of fractures in highly deviated wells with perforations. The experimental results indicate that the fracture geometry is affected by horizontal stress contrast, deviation, azimuth, and perforation phase angle. If the deviation angle is less than 20° or larger than 80°, the azimuth angle less than 30°, the horizontal stress contrast larger than 3 MPa, and perforation phase angle 60°, the fractures will propagate smoothly and the fracture geometry is simple; if the deviation angle is between 40° and 60°, the azimuth angle larger than 30°, the horizontal stress contrast less than 3 MPa, and the perforation phase angle 90°, the fracture geometry will be complex with high distortion and many sub-fractures. The result here agrees to the statistics of fracturing operations in 403X1 Block in Jidong oilfield, and could contribute to improving the success rate of fracturing jobs in highly deviated wells.