A Novel Technology for Through Tubing Perforation in Highly Deviated Wells Where Electric Line Is Limited

Abstract

Electric line remedial work such as through tubing perforation has been successfully carried out in most vertical/deviated wells. However, in high angle/horizontal wells it has become a major undertaking due to inability of the gravity-assisted, electric line to convey perforating guns to angles greater than 65°. With this electric line limitation, the options available for deploying the guns are limited to wireline tractor and e-coiled tubing since most through tubing perforation are done in real time. Apart from space constraint at the wellsite and cumbersome logistics, the main set back with the e-coil is its unavailability, while the tractor has high operational cost. This paper outlines the successful perforation of horizontal wells in the Niger Delta while addressing the operational issues encountered. The first case history is Addax ORW-11H, a horizontal well planned to have the lateral section slimmed down to 6 in. hole. After successfully drilling the hole to target depth (TD), a 6-in. hole-opener was deployed on 3½ in. drill pipe to condition the well before running the 4½ in. liner. In an attempt to re-run the hole-opener, the bottomhole assembly (BHA) got stuck 20 ft off target depth. After several unsuccessful attempts to recover the BHA, it was decided to perforate the 3½ in. drill pipe to provide a conduit for production. The challenge was deploying the gun at 90°deviation, correlating and perforating on depth without e-coil. This was overcome by using an intelligent memory correlating and perforating tool to perforate the drill pipe and communicate with the reservoir. On completion, the well delivered 1,400 bopd with 0% water cut. The second case history is Chevron Okan Well Y, which was drilled and completed as a horizontal gravity waterflood injection well. The initial 20,000-bwpd water injection began to drop and later quit due to sand accumulation and plugging. After an unsuccessful sand cleanout, the proposed remedial action was to add 40 ft of additional perforations shallower in the target reservoir to provide access for the desired injection rates for the well and help increase recovery. Initial attempt to run electric line to TD failed due to inclination of over 77°, but the well was later perforated successfully using the same novel technology with significant cost reduction.