Conformance Control Completion Unlocks Production Horizons of Tengiz Field

Abstract

The team evaluated multiple options for conformance control, with the primary focus on shutting off water. The team broadened the focus to include gas shut off, as well as implementation in the sour gas injection wells, and the water injection wells. The new completions have become the preferred completion for most of the wells. The conformance control packer assembly is selected based on the openhole caliper logs, pressure measurements, drilling breaks, fluid saturations and the thickness of the reservoir intervals. After the drilling rig runs the completion, the wells are completed with a coiled tubing unit. The coiled tubing tools and procedures have improved since the initial swell packer completions. Many of the new wells use smart coil with embedded fiber optic cable to help ensure a successful completion. The swell packer completions have been very successful as a whole, but not every swell packer is effective in isolating between layers. The Distributed Temperature Sensing (DTS) has been very useful in identifying both leaking packers, as well as communication between zones from within the reservoir. There are several benefits of using the swell packers for mechanical diversion of stimulation fluids. Without the swell packer completions, the average treated zone was 500m thick. Initially, most conformance control completions consisted of three to four packers. Since then the average number of packers has increased to five to six packers per well. Most stimulation treatments now target an interval of less than 100m. There have been several major rig workovers (MRWO) in the sour gas injection area of the field. Comparisons pre and post MRWO well performance indicate that the swell packer improved the productivity of wells. This paper shows how the swell packer completions have helped to reduce unwanted fluids and enhanced the oil production capability of the wells. It will describe the selection process for packer placement, and the success rate of these packers. The paper also covers the evolution of the coiled tubing procedures that helped to make the conformance control program a success.