Integrated Gas Lift Completion String for Ultra-Deep Reservoir

Kenjiyak Oilfield, in Kazakhstan, is an ultra-deep oil reservoir of low porosity and ultra-low permeability, causing a myriad of technical problems when produced with conventional gas lift string. To address these problems, an integrated gas lift completion string has been developed. The completion string integrates fracturing, drainage and gas lift processes, and is capable of accomplishing multiple operations of zonal fracturing, quick flowback, reservoir protection, retrieving and gas lift production, etc., in one trip. This paper introduces the structure and working principles of this string, structural and performance characteristics of the key supporting tools. Meanwhile, it analyses the retrievable gas lift mandrel and drillable-retrievable packer. 47 wells' field application showed this completion string's maximum application was 4,287.63m, the maximum working pressure was 68MPa, the maximum single well daily yield was about 130t and the average drainage duration was 3 days, presenting significant operation performances. The integrated gas lift completion string is expected to provide strong technical support for oil production with low cost and high efficiency, thereby accelerating the development of overseas oilfields.