This paper discusses the planning and execution of the first successful gas shut-off (GSO) operation in a highly deviated well in the ACG Field using a polymer technology inside an open hole gravel pack (OHGP) completion, deployed with coiled tubing. This operation is also a first for the region.

The Azeri-Chirag-Gunashli (ACG) Field, a massive field located in the Caspian Sea, features multilayered sandstone and weakly consolidated reservoir zones, where open hole gravel pack (OHGP) completions have become the standard design for producing wells. The typical OHGP length is around 500 meters. As the field has started to mature and increased depletion, gas breakthrough has become increasingly common, impacting oil production. The primary challenges in shutting off gas in wells completed with a gravel pack are the presence of highly permeable annular flow paths between base pipe and wire-wraps and the pressure differences between producing zones.

An effort to shut off gas using polymer treatment was trialed in an OHGP well with a high gas-oil ratio (GOR). This well was completed in 2017, and GOR had been rising steadily to 4500 scf/stb. Production logging confirmed the main gas contribution zone. Due to its high effectiveness and capability of penetrating the near-wellbore matrix, a polyacrylamide-based gel treatment was chosen to isolate the gas-producing layer and increase offtake from different layers. To prevent the treatment from blocking other producing zones, the bottom zone was isolated by pumping a temporary viscoelastic surfactant. A bridge plug was then installed at the base of the target zone on top of the spotted temporary chemical and was successfully retrieved at the end of the operation. To prevent gel migration to the zone above, a thru-tubing inflatable packer was set at ~43meters above the target zone inside the 5" OHGP screen. Coiled tubing with telemetry was used for precise real-time reading of downhole conditions, and a total of 58 barrels of the polymer was pumped through coiled tubing to achieve 1.5 feet of penetration.

The first polymer gas shut-off inside an OHGP well was successfully performed without any issues. The treatment resulted in an increase in oil production by 700 barrels per day (bpd) and a ~68% reduction in gas production from 20 mmscfd to 6 mmscfd. The polyacrylamide-based gel treatment proved to be highly effective for gas shut-off in OHGP wells and did not restrict the wellbore compared to the tubing patch technique previously trialed in ACG. This successful result opens the opportunity to apply the same technique to other wells in ACG encountering similar problems.

This is the first successful application of polyacrylamide-based gel treatment in OHGP completion in the bp Azerbaijan region. The system can be replicated in the industry utilizing similar techniques, providing a reliable solution for managing gas shut-off and enhancing oil production in mature fields.