Abstract The Ahmadi field located in South-East Kuwait has a prolific low matrix permeability carbonate formation with moderate to high oil viscosity. During the initial field development phase, the field started suffering from significant production decline and rapid reservoir pressure depletion. These challenges led to stimulating these wells, further driven by multiple factors—the desire to connect the natural fractures, to fully drain formation and to increase the Estimated ultimate recovery (EUR) of the well through achieving additional stimulated reservoir. This paper presents the entire process of identification of a potential candidate including operational preparations, execution, and analysis of post-treatment results. After the well candidate selection, developing a solution phase that will accomplish the treatment's goal and addressing reservoir challenges such as stimulation of depletion, high fluid leak-off tendency is one of the most important challenges. The well was treated using High quality Nitrogen (N2) foam with High Viscosity Friction Reducer (HVFR) PAD fluid and modified single phase retarded acid system (mSPRAS) to ensure deep and branched ramifications. The Nitrogen (N2) Foam acid selected, is a finely dispersed mixture of nitrogen gas bubbles within hydrochloric acid liquid which increases the volume of the active acid, improves penetration, and diverts fluid from high permeability zones into low permeability zones. Holistic design diagnostics with memory gauge data, Diagnostic fracture injection test (DFIT) analysis and swift temperature log analysis for frac height computation was conducted, to ensure revalidation of fracture simulations and to tune the "Tailor-Fit" fracturing design rather than conventional cookie cutter method. Energized acidfracs helped in reducing fluid usage and promoting higher length growth with improved fracture width relative to low viscosity fluids- resulting in an optimum fracture geometry and superior conductivity enhancement. Based on the comparative valuation completed on nearby wells, the use of energized fracs is shown to create significantly improved performance over those wells fractured with non-energized fluids. Temperature logs, bottom-hole data frac analysis, sonic log data confirmed that the fracture remains within this layer with an average half-length of 370 ft. The presence of existing natural fractures was inferred through a significant permeability increase observed, reaching up to 1.2 Darcy, likely attributable to substantial fracture apertures. Analysis of diagnostic ISIP, closure pressure, and temporal changes indicated a well-connected fracture network extending away from the wellbore. Post treatment production increased 6 folds per day. This paper summarizes the candidate selection criteria, application of this unique stimulation design in Kuwait, operational procedures, diagnostics tools, well clean-up and production performance aspects of this treatment. Success of this technique is crucial for the Ahmadi field to overcome production decline and reservoir pressure depletion and effectively stimulate this prolific carbonate formation, increasing the stimulated reservoir volume to continue rising field production capacity. The learnings presented can be utilized for similar challenges in other fields.
Al-Kandari et al. (Tue,) studied this question.
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