UAE which has traditionally been an oil producing country is reassessing the nation's energy production strategy and are appraising alternate energy sources. A part of this strategy includes exploring and assessing the potential of their unconventional and tight gas reservoirs. In order produce gas at economic rates from these deep unconventional reservoirs hydraulic fracturing is a vital technology to unlock the reservoir potential and enable hydrocarbon flow to surface. The first onshore hydraulic fracturing treatment in UAE was a challenging operation since the target formation was never successfully fractured previously. The expected breakdown pressure, insitu stresses and pore pressure regimes were unknown. A robust workflow was put into place using global and regional experience. An integrated formation evaluation was conducted during drilling and logging the vertical wellbore in order to select target zones and perforating intervals. Triaxial testing and ultrasonic measurements were conducted on core samples from the treatment well to calibrate the Geomechanical model before the hydraulic fracture treatment execution. Detailed lab testing was carried out to assist fracturing fluid and proppant selection. Multiple hydraulic fracturing simulations were conducted to define the final stimulation treatment program. Evaluation of the target UAE unconventional gas reservoir during the drilling and evaluation phase indicated the formation possessed high static stiffness, highly laminated depositional environment, significant overpressure and high insitu horizontal stresses. These formation characteristics posed some challenges during the hydraulic fracturing design and execution. High fracturing treatment pressures and propellant based perforation charges were required to effectively breakdown the formation in order to place the proppant into the fracture during execution. The stimulated target zone showed good initial gas production post treatment execution, which met the primary objective of proving recoverable gas in place. The hydraulic fracturing lessons learned from this first onshore unconventional well will be applied to future exploration and appraisal wells to ensure stimulation success and hydrocarbon deliverability. Unlocking the large quantity of gas from these organic rich carbonate reservoirs will play a significant role in UAE hydrocarbon production strategy.

This paper covers four case histories of refracturing technology applied to under-stimulated wells, along with the benefits and well economics of returning these older wells to profitable production. Refracturing candidate selection criteria, operational execution, and well results for the four full-lateral refracturing projects are discussed. Refracturing candidate selection criteria were developed based on several parameters tied to improved production and project economics. Liner refrac methods were evaluated to select wells and field trials were performed to verify each method provided both ease of execution and isolation. Cemented liners and several expandable liner systems were evaluated. With effective mechanical isolation, highly effective modern frac designs can be applied successfully to refracs. The refracturing candidate wells outperformed the expected type curve and yielded positive economics. One cemented liner refrac showed poor isolation during treatment. Expandable liners showed good isolation, but some expandable technologies were better than others were. Rigorous planning and engineering were considered crucial to ensure trouble-free operational execution and to deliver an optimum wellbore for refracturing purposes. The criteria for refracs included in this paper are directly applicable for evaluating refrac candidates. The experience with isolation methods enables engineers to select the proper technology to seal old perforations.