Successful Implementation of Blast Joint Perforation Technology in a Dual String Completion

Abstract

The results of computer simulations and laboratory tests have been applied at Porth field in Nigeria to achieve a successful perforation through a blast joint to access hydrocarbon behind pipe. Accessing hydrocarbons behind pipe in multizone completions can be difficult. The options are; an expensive rig-based workover or a cost-effective, rigless, through-tubing perforation. For a rigless through-tubing option, the detonated perforation charges must pass through a blast joint, the casing and the cement and then into the target reservoir. The major concern is usually whether there will be enough penetration {Burky 2018} into the target reservoir interval, given the layers of material resistance that the charges will have to overcome, starting at the blast joint. The Blast joint has a higher wall thickness and a larger outer diameter than that of the conventional tubing string to mitigate against erosion from producing the target interval behind pipe. The goal in perforation operations is achieving the maximum production while reducing perforation damage. {Jackson 2016}. Computer simulations and laboratory tests for a well at Porth field in Nigeria were carried out to determine the potential for successful perforation through a blast joint to access hydrocarbon behind pipe. Coupon tests using different gun sizes and charges where simulated and tested to ascertain the most effective option to achieve the desired reservoir penetration. Both computer simulations and laboratory test results showed that a reasonable depth of penetration into the target reservoir interval was possible to achieve. The perforation job using a 1.56-in., six-shots-per-foot (6 spf), 60° phasing gun was successfully carried out and the well has been tested to a potential of 780bbl/d at a tubing head pressure of 943psi and choke size 20/64th. This success lays the foundation for going after other similar opportunities locked in behind-pipe previously thought inaccessible owing to the presence of a blast joint across the target interval. Associated rig costs for a workover of up to $10 million can be saved on each opportunity using this approach.