Deciphering the Makhul Formation: Overcoming Geological and Geomechanical Challenges to Unlock Reservoir Potential

Abstract The unconventional Makhul Formation in Minagish field west Kuwait was evaluated and stimulated for the first time, requiring an integrated geological, geomechanical and stimulation approach to optimize well placement and acid fracturing performance. The formation is characterized by a high-stress strike-slip to reverse fault regime, carbonate heterogeneity, and low permeability (0.1–1 mD). This study aims to assess acid fracturing effectiveness, near-wellbore behavior, and fracture-reservoir connectivity using geomechanical modeling, advanced fluid systems, and data-driven stimulation analysis for future field development in west Kuwait. A comprehensive geomechanical evaluation was conducted, incorporating rock mechanics testing, stress analysis, and 1D mechanical earth modeling (MEM). The stimulation workflow involved 12 open-hole multistage completion (OHMSC), deploying Single-Phase Retarded Acid System (SPRAS) as the primary extended-contact acid system for deep wormhole penetration and fracture conductivity enhancement. Pressure decline diagnostics in Data Frac analysis provided insights into fracture behavior, fluid leak-off, and reservoir pressure response. The treatments were executed at 30 barrel per minute (bpm), maintaining surface treating pressures below 12,000 psi, ensuring efficient fracture propagation and maximizing reservoir contact across the Makhul Formation. Ten out of twelve planned acid fracturing stages were successfully completed, covering most of the Makhul Formation and demonstrating good hydraulic fracture connectivity with the reservoir. Post-stimulation coiled tubing milling confirmed full-bore access, followed by nitrogen lifting, which yielded unprecedented production results from the formation. Geomechanical analysis confirmed high stress anisotropy, with an estimated closure pressure of 11,034 psi and a reservoir pressure of 7,400 psi. The low fracture fluid efficiency of 36% indicated significant fluid loss to natural fractures, necessitating advanced fluid control strategies in future treatments. The fracture compliance effect was observed during pressure decline analysis, suggesting partial fracture closure and width changes post-treatment. The SPRAS exhibited high dissolution capacity and effective viscous fingering, creating deep conductive fractures, making it suitable for future acid fracturing campaigns in the field. This study establishes a proven workflow for optimizing acid fracturing in highly stressed carbonate formations, enabling the development of the Makhul reservoir as a new production target in west Kuwait's Minagish Field. This case study represents the first-ever stimulation of the Makhul Formation, integrating geomechanical modeling, acid fracturing, and data-driven analysis to overcome reservoir challenges. The findings provide key insights into fluid behavior, stress anisotropy, and fracture propagation, offering a validated methodology for unlocking unconventional carbonate reservoirs. The success of this treatment sets a benchmark for future acid fracturing strategies and field development in Kuwait's deep, highly stressed formations.