预置多裂缝压裂井下工具的设计与应用

针对低渗油田的渗透率低和油流阻力大等特点,结合水力喷射技术和加砂压裂工艺技术,根据预置多裂缝压裂技术的机理,设计了多裂缝压裂专用井下工具。该工具通过微细限流孔和溢流阀共同作用实现工具的定点喷射和缓慢移动,高压流体通过喷射工具,将高压能量转换成动能,在地层内形成2个对称的扁纺锤体裂缝,实现了井下压裂预置新裂缝的效果。预置的扁椭圆纺锤体新裂缝会使缝周边岩层松弛,应力下降,渗透率上升。现场试验表明,预置多裂缝压裂技术能有效改善地层渗透率,对于低渗透油田的增产增注有良好的效果。

Design and application of the preset multi-fracture fracturing downhole tool

Considering the characteristics of the low permeability and great oil flow resistance in low-permeability oilfields,referring to the hydraulic jet technology and sand fracturing technology and according to the mechanism of the preset multi-fracture fracturing technology,the special multi-fracture fracturing downhole tool was designed.The tool makes use of the reaction of the fine flow-limiting hole and overflow valve to achieve its fixed-point jet and slow movement.The high-pressure fluid converts high-pressure energy into kinetic energy by means of the jet tool,resulting in the formation of two symmetric flat-spindle fractures in the formation and achieving the effect of downhole fracturing preset new fractures.The preset new fracture of the flat-elliptic spindle will make the rock around the fracture get loose,and cause the stress to go down and the permeability to go up.The field experiment shows that the preset multi-fracture fracturing technology can effectively improve the formation permeability,produce a desirable effect on the well simulation in low-permeability oilfields and achieve good economic benefits.