Successful Gas Shut Off Operation using a Coiled Tubing Telemetry System: A Case History

Abstract

Abstract In a deviated well in Caspian Sea gas oil ratio (GOR) increased rapidly in 2017. The result was an oil rate decline with several choke backs to manage GOR build-up. After performing two production-logging jobs, it was confirm that 76% of the gas production was coming from four upper perforations. The main objective was to perform a Gas Shut off (GSO) treatment in two stages to reduce gas production by squeezing polymer into the formation and setting packers at 59° deviation inside 9-5/8 in. casing for temporarily isolation of middle and lower production sands. Fifteen runs were perform with a tube wire-enabled CT telemetry (CTT) system which consists of a customized bottomhole assembly (BHA) that instantaneously transmits differential pressure, temperature, depth data to surface through a non-intrusive tube wire installed inside the CT. For the first time in the region, a tension, compression and torque (TCT) sub-assembly was deploy to control the entire set/retrieve process with accurate downhole upward/downward forces. CTT technology was a key element to successfully set two Thru Tubing Inflatable Retrievable Packers (TTIRP) by doing casing collar locator (CCL) correlations at tubing end which was 133 m and 228 m (MD) shallower from setting depths. In addition, during second GSO operation, polymer crosslink time was modify based on actual bottomhole temperature recorded with CTT system. Finally, during third GSO treatment placement was improve spotting more GSO system in casing section avoiding further treatments. After successful placement of the GSO system, a drop from 15.5 to 4.5 MMscf/day in gas production was observed along with GOR reduction from 11,000 to 750 MMscf/bbl and oil rate increment from 1.4 to 6.04 Mbpd. Furthermore, after gas reduction operator was able to produce between 1.5 to 2.0 Mbpd from other wells that were choke back based on gas handling capabilities limitations The novelty of using the CTT system and TCT sub-assembly for real-time monitoring of BHA data was proven for not only positioning two TTIRP, modifying polymers crosslink design, placing polymer precisely across target intervals and retrieve two TTIRP that at the end provide direct and positive financial impact for the operator.