Noelle Trotter and Mickey Bohn
Oxy
The Oxy Texas Delaware North Business Unit (TXDN) experiences frequent premature failures from severe downhole corrosion due to reservoir conditions and chemical undertreatment in wells with <1yr operating life. Typical damage occurs on undertreated annular gas lift wells near cap-string clamps/bands. Turbulent flow occurs on these components from high velocity flowrates, stripping chemical protection for corrosion to develop. From Jan 2022 to May 2025, ~28% of rig work addressed corrosion-induced tubing failures, costing $63.7MM cumulatively. In TXDN, ~15% of wells are chemically undertreated, decreasing runtimes and increasing failures.
TXDN is trialing three solutions to mitigate downhole tubing corrosion: 1) Externally coated tubing, 2) Internal capillary strings for chemical injection, and 3) Automated chemical injection. Since Oct 2024, 13 resin-coated tubing strings from BondCoat have been ran without failure at an economically incremental cost $6/ft. Since Nov 2024, two internal cap strings have been installed successfully for $13M per install incrementally. Both methods eliminate external clamps/bands--the main corrosion induced failure locations. To address undertreatment, TXDN implemented automated injection logic using NEXUS well test data, enabling daily rate adjustments and real-time monitoring, reducing reliance on weekly vendor changes, and keeping chemical treatments consistently on target.
While still in the trial stages, TXDN has successfully implemented automated chemical injection logic, external tubing coatings and internal capillary strings as methods for corrosion prevention. The measure of success will be if the tubing strings can last long enough for the wells to require conversion from annular flow to tubing flow gas lift, indicating the elimination of a premature failure and costly workover. This would deliver approximately $18.6MM/year in savings due to unnecessary workovers being eliminated. Measuring treatment targets from automated chemical injection is done in real time through Cygnet and Pi trends. With the automated chemical trials scaled up, the team is projecting a discounted cash flow of ~$610M across new drills for EOY 2025 through 2026.
Looking forward, automated chemical logic is in the process of scaling up all existing wells with DC3 controllers and installed for all future wedge wells. Cygnet and Pi screen surveillance are being built out in tandem to controller logic implementation.
The internal cap string tool has been redesigned so that it can accommodate 2-3/8", 2-7/8", and 3-1/2", tubing and trials for 2-3/8" tubing during first lift installs will begin in Aug 2025. Along with externally coating tubing, these technologies will be considered for TXDN "One Lift" Trials including Hybrid and/or EC Mandrel gas lift designs.