Integrated Approach for Multi-Stage Fracturing MSF Completion Deployment in Deep Carbonate Reservoirs Improved Efficiency, Saved 2 Days Per Well With 100% Success Rate

Abstract

In the past decades, new innovations increased the efficiency and economic feasibility of Hydraulic fracturing in the United States. That has opened untapped unconventional shale gas reservoirs and turned the U.S. into one of the world’s largest gas producers. These results eventually led to a global increase in the popularity of Multi-Stage Fracturing (MSF) completion systems. In the middle east, this type of completion is now run in vertical and horizontal holes, with laterals extending up to 7000 ft and with a pressure over balance as high as 3000 psi. These laterals are typically drilled in deep conventional oil and gas reservoirs with significantly higher differential and mechanical sticking risks compared to the impermeable shale reservoirs. This has called for an integrated strategy that prevents and mitigates these catastrophic risks. Tackling these risks starts in the planning phase by evaluating the offset wells, formation characteristics, overbalance, stress direction the well is drilled in and the stress regime in the area. This is done through a comprehensive geomechanical study that produces a Mechanical Earth Model (MEM). Its results are used to reach an optimum design for the drilling fluid and bridging plan that balances the "stable mud window" with the risk of differential sticking. A completely new approach has been taken for entire completion phase of the well, with an emphasis on reducing the open hole exposure time and reducing formation fatigue caused by the fluctuations in downhole equivalent circulating density (ECD). Prior to deploying the Multi-Stage Fracturing (MSF) completion string, its final design is simulated with specific software for an optimized centralization plan that gives the best possible standoff. Finally, during the deployment of the completion string, the Torque and drag measure are taken and any signs of differential or mechanical sticking are dealt with before they evolve into a stuck pipe situation. This paper describes the whole integrated approach together with the results of the implementation carried out in several wells with different subsurface conditions, detailing the steps taken including the risk assessment and the recommendations implemented.