The Development and Testing of a Screen Multi-Stage Jetting and Unfreezing Tool for Horizontal Wells

Failed screens are often stuck by sand between the screen and the casing in horizontal wells.There are many difficulties that occur in conjunction with the rapid releas of the stuck tool and fishing processes.So,to solve the problem,a diversion-type small-diameter jetting device and integrated multi-stage sealing and sand-washing device were independently designed and developed.Their main purpose is toact as a screen for multi-stage jetting and unfreezing technology in horizontal wells.The diversion-type small-diameter jetting device is used to perform sandblasting perforation at the predetermined positions on the inner wall of failed screen.After the well has been perforated,an integrated multi-stage sealing and sand-washing device is run and set between the adjacent holes to perform staged sand-washing to reversely wash out the sand between the screen and production casing.This will effectively release the stuck long screen at any position.The results of lab tests showed that the optimal screen jetting parameters include flow rate of 300-400 L/min,sand ratio of 3%-5%,abrasive particle size of 0.425-0.850 mm,working pressure of 16-25 MPa,and jetting period of 10 min.This technology has been field tested in four wells in the Chenghai No.1 area of the Dagang seabeach oilfield.The diameter of perforated hole was 14.0-18.0 mm,and an effective sand-washing channel was established.The success rate of the screen releasing was 100%,and all the failed screens were retrieved effectively.The successful development of the multi-stage jetting and unfreezing tool for horizontal wells has provided a brand-new solution for the releasing and fishing of stuck long screens in complex wells.The technique is effective in horizontal wells and it exhibits very good prospects for its application and deployment.