Success Story of Repairing Casing Leak Near Surface Using a Bandage Cementing Technique in Central Sumatra Basin

Abstract

Abstract During the water injector workover campaign in 2018, some casing leakage near the surface was identified (depth range 10 to 300 ftRT). Several attempts were made to seal the leakage, but none of them succeeded. In response to investigation, a specific cementing technique was developed, called "bandage cementing", and it was successful in repairing casing leaks near the surface with over 75% success rate. The focus of this technique is to build a column of cement in annulus between production casing and surface casing to create a "bandage" covering all leaking points in production casing. To build it, a cement evaluation log was run to investigate the presence of cement in annulus surface-production casing. A perforation gun was then run into the well to make some holes in production casing below leaking points. Injectivity and communication test was then performed to check the connection between perforation hole and leaking points and casing valve in surface. Once communication confirmed, cement retainer was then deployed to perform cementing jobs inside production casing and in annulus surface-production casing. The goal is to fill the void in annulus between surface and production casing with cement to build a cement column covering the casing leak. This repair casing technique was applied to 4 (four) water injector wells with casing leak problems. The repair job succeeds to seal the casing leaks and all wells were put back on injection. They passed the pressure test and confirmed the leak was completely sealed. The key success for this repair casing method lies in how well we can place cement columns to surround the leak points from both below and above the leak. Several observations include whether the injectivity connection could be established between leaking points, perforation hole and casing valve and how much barrel of cement could be placed behind the casing are the supporting factors to achieve it. The goal of this paper is to provide an alternative to casing repair for wells with casing leak problems near the surface which are usually very difficult to repair and take a lot of time on the rig to repair.