Successful Completion of CO2-Foamed Hydraulic Acid Fracturing Pilot Campaign in Jurassic Gas Wells in Kuwait

Abstract

Jurassic Gas Field Development Group (GFDJ) of Kuwait Oil Company (KOC) completed the first ever CO2 foamed acid frac pilot campaign in four Jurassic sour HTHP wells. This innovative technology was utilized for the first time in KOC's history safely and effectively with exemplary well performance. GFDJ had been pursuing the CO2-foamed acid fracturing technology since 2019 with the objective of improving the stimulation and hydraulic fracturing efficiency in the Jurassic Middle Marrat formation. CO2-foamed acid fracs have several advantages over other stimulation techniques: CO2 is a miscible and non-damaging fluid which blends in water and also mixes with hydrocarbons. Pumped as a liquid and slightly heavier than water, leading to lower treating pressures due to heavier hydrostatic head. Effective in treating lower-pressured/partially-depleted, good K.H (permeability-height function) carbonate reservoirs. Reduces water-based gels and overall frac-load volume by the percentage of CO2 pumped in the frac fluid system (40% by volume is utilized in this pilot). Energizes the frac fluid and stays in solution until it heats up to gas. This property ensures the frac load recovery is achieved throughout the flowback. Eliminates the need to activate the well after the frac with CT/N2 applications potentially saving time and money to KOC. Has potential to lighten up the heavier ends of the hydrocarbons due to its miscible properties, hence may help with better hydrocarbon inflow. Creates stable foam structure with the frac fluid, increasing the frac fluid viscosity hence has the potential to generate better frac geometry and larger stimulated rock volume (SRV). A four-well campaign was completed within 12 months period. Three different monobore completion wells and one 3-1/2″ tubing with 5″ liner completion well were fracture-treated using an average of 40% downhole quality CO2-foam pumped at an average rate of 30 bpm. Different service companies and their fluid systems, as well as their operational capabilities were utilized in operations with exemplary clean up and production test results that surpassed the expectations of the asset. Additionally, pumping cryogenic CO2 at high ambient desert temperatures of September in Kuwait, safely, and operationally effectively is a major milestone and achievement in itself. This paper summarizes the design, operational, well clean-up and production performance details of the CO2 campaign. Learnings of the GFDJ asset will be shared in order to benefit from the learning curve that KOC went through in implementing this strategic application. Success of novel CO2 stimulation technique is critical for the GFDJ asset to continue expanding its production capacity in next 2-3 years while maintaining the strong production plateau achieved in 2021. Future plans of the assets will also be discussed to ensure cross-boundary opportunity realization will be possible in the industry for the region.