As a low-cost alternative to expensive rig workovers, placement of a cement packer between tubing and casing has been previously applied in Malaysia. The purpose is to create a new annular barrier above the existing production packer to gain access to behind-casing opportunities (BCOs) or pay zones, removing the need for a workover. These pay zones, usually with minor or unknown production potential, have been left by the operator during initial completion because there were larger pay zones in deeper reservoirs. Cement packer placement can be achieved using basic intervention equipment as opposed to more expensive workover units.
The cement packer technique eliminates the need of recompleting the well with a conventional workover rig and reduces operational complications together with cost. There are different methods to deploy a cement packer. The highest chance of success, particularly when larger volumes of cement are needed, is using coiled tubing (CT) as the primary method to place the cement slurry in the tubing/casing annulus. In this method, a cement retainer was used and conveyed with CT. CT provides the ability to sting into the retainer and cement being displaced through the coil, ensuring all completion accessories have no contact with cement slurry which can impair their functionality, and also prevents U-tube effect of the slurry once cement is placed behind the tubing. After the cement is set, a cement bond log (CBL) is run to confirm cement integrity behind the completion tubing before adding new perforations.
This paper presents the successful cement packer placement operation with the help of the CT executed on an offshore platform in Peninsular Malaysia. A potential pay zone of the I-Group reservoir was discovered in the field after running pulsed-neutron cased-hole saturation logging tools, which are situated above the production packer; appraisal was required because of the unknown fluid type. Close collaboration among various parties in candidate selection, job preparation and design, cement laboratory testing, and operational planning and execution, were keys to the success of this pilot operation. By proving operational feasibility and economics, the technique opened up additional opportunities in restoring idle wells with bypassed reserves within the same field.