Pillar Frac Strategy in BP Oman: Case Studies of Implementation in Barik and Forecasted Challenges in Miqrat

Abstract Hydraulic fracturing has been successfully utilized for several decades to develop tight gas and, more recently, unconventional plays, resulting in improved well productivity and economics. This is achieved by increasing the reservoir surface area exposed to production and the resulting rate acceleration. The Khazzan field, located in central Oman, is a tight gas play developed on two main reservoirs: Miqrat and Barik. The Barik sandstone is further divided into three zones: Upper (UB), Middle (MB, and Lower Barik (LB). The UB and LB zones have poorer reservoir quality, characterized by lower average permeability, thinner sandstone layers, and more frequent interbedded mudstones, often leading to early termination of frac treatments. The Middle Barik sandstone does not present major execution difficulties, but several studies have indicated that increased frac length and better frac conductivity are the two main components needed to improve frac and well performance. To address these surface and subsurface challenges, the industry has developed and implemented various methodologies with varying success rates. One of these techniques, chosen for the trials described in this paper, is Channel Fracturing (CF). CF utilizes proppant mixed with fibers in combination with a surface pulse pumping methodology, alternating short bursts of proppant slurry with clean fluid. CF aims to create proppant pillars to hold the fracture open. The pulsing results in infinite conductive channels inside the formation, instead of the conventional continuous proppant pack. CF, with its pulses and better proppant transport from fibers, also results in lower chances of screen out and lower injection pressures. The lower injection pressure could potentially aid in better containment as the net pressure inside the frac is reduced compared to a conventional design. Once the channels and pillars are created during the treatment injection, the fibers dissolve during the shut-in period as the temperature rises, creating highly conductive channels between the pillars. The results of a high-resolution and advanced simulator incorporating all the physical laws interacting during a fracture treatment were used to optimize the designs for the Upper, Middle, and LB formations. This paper describes the details of four CF trials implemented in the Khazzan field and how the technology successfully achieved the objectives of the trial. The proppant pulsing methodology minimized proppant entry largely due to the narrow fracture width and near-wellbore fracture complexity typical of the Upper and LB. The higher volume of fluids associated with CF created larger frac geometry, and the successful placement of the designed frac size resulted in better well productivity. The paper discusses observations in wells with CF applied in some zones, insights from the findings after implementing CF, and the way forward in terms of operationalizing CF to unlock hydrocarbon resources from tighter rocks. This work offers an example of the workflow utilized to plan and implement CF technology and how this technology could potentially represent a critical component to enable high-density frac in horizontal wells while minimizing screen out occurrences and maximizing frac conductivity. This is achieved by shifting the conductivity from a continuous high-quality proppant pack to a channel and pillar environment where proppant requirements could be reduced without impacting overall frac conductivity. All these factors can reduce the economic impact of contingencies and proppant requirements.