段内多簇暂堵压裂中暂堵球直径优化研究

Research on Optimization of Plugging Ball Diameter for Multi-cluster Temporary Plugging Fracturing

段内多簇暂堵压裂过程中,持续加砂造成孔眼冲蚀,直径变大。按照初始孔眼尺寸设计暂堵球粒径对封孔封堵效果差,段内多裂缝难以实现均衡扩展,造成水平井整体改造效果不理想。为优化暂堵球直径,提高孔眼封堵效果,开展了地面矿场孔眼极限冲蚀试验,结合井下鹰眼成像监测结果,明确了极限冲蚀下孔径增大幅度。通过三维建模几何匹配方法,优化了暂堵球直径并通过地面暂堵试验和井下暂堵压裂矿场试验加以验证。研究结果表明:极限冲蚀情况下,孔眼内部冲蚀程度远大于外部,孔眼形状由规则的圆形通孔变为喇叭形孔,极限冲蚀后内径介于区间30~35 mm,优化暂堵球直径区间为15~22 mm,为避免暂堵球缩径飞出孔眼,确定暂堵球最佳直径为22 mm;地面矿场暂堵试验证实了22 mm暂堵球可以卡封孔眼不脱落且起压速度快。研究成果可为现场选择暂堵球直径提供指导,提高暂堵球坐封效率与压裂改造效果。

During multi-cluster temporary plugging fracturing within one segment,continuous sand addition causes perforation erosion and increases the diameter of the perforation.The ball-shaped diverters designed according to the initial perforation size has poor plugging effect,and it is difficult to realize balanced propagation of multiple fractures within one fracturing segment,resulting in unsatisfactory overall stimulation effect of horizontal wells.To optimize the temporary plugging ball diameter and improve the hole plugging effect,this work carried out the ground ultimate erosion test of the perforation,and combined with the results of the downhole eagle eye imaging monitoring,the increase in aperture diameter under the ultimate erosion was clarified.Through the threedimensional modeling geometric matching method,the diameter of the temporary plugging ball is optimized and verified by the surface temporary plugging test and the downhole temporary plugging fracturing field test.The research results show that:in the case of extreme erosion,the degree of erosion inside the hole is much greater than that outside the hole,and the shape of the hole changes from a regular circular through hole to a trumpet-shaped hole.After the limit erosion,the inner diameter is in the range of 30-35 mm.The diameter range of the ball is 15-22 mm.In order to prevent the temporary plugging ball from shrinking and getting out of the hole,the optimal diameter of the temporary plugging ball is determined to be 22 mm.The research results can provide guidance for selecting the diameter of the temporary plugging ball on site,and improve the setting efficiency of the temporary plugging ball and the effect of fracturing.