Abstract
Economic recovery and production of non-associated gas from the tight clastic reservoirs in Saudi Arabia faces some challenges resulting from high bottomhole temperature, high in-situ stress, low permeability, and high Young's modulus and rock compressive strength. Hydraulic fracturing, a necessary means to exploit the tight reservoirs, encounters constrains such as high fracture initiation and treating pressure, risk of pre-mature screen-out, and conductivity degradation with time. A conventional fracturing treatment in such challenging environment necessitates increased polymer loading in fracturing fluids to stabilize fluid viscosity and using smaller size proppant at low concentrations to ensure proppant placement. This results in shorter effective fracture half-length and low fracture conductivity. Reduced contact area decreases production potential. Additionally, high polymer loading is not easily breakable and may create major damage to the proppant pack, thereby substantially reducing fracture conductivity. The challenges compound when the reservoir is relatively tight and often cannot generate enough energy to clean up the injected fracturing fluids. To overcome these challenges, channel fracturing was introduced where proppants are added in pulses in fracturing fluids along with dissolvable fibers creating stacks of pillar-like structure inside the fracture. These proppant pillars stay suspended and are held by the fibers during the treatment. Once the pumping is stopped, the fracture closes on the pillars and the fibers degrade under formation temperature. These pillars hold the fracture open and act as columns; the void surrounding them are essentially stable channels along the entire geometry of the fracture that provide open pathway for hydrocarbons to flow in a near-infinite conductivity environment. The technology also reduces the amount of proppant pumped compared to a conventional treatment, and pulsation of proppant during pumping reduces the risk of an early screen-out.
