Difficulties of hydrofracturing in sandstone – experimental study

Hydrofracturing in sandstone is not an easy task. Sandstone is porous; fluid dissipation is common hence unable to obtain breakdown pressures in certain flow rates (0.0000005–0.0001 m3/s). The higher flow rate (0.00025 m3/s) is ascertained to determine the fracturing pressures. Due to this, fracture propagation and delineation are observed 1. To enhance, an experimental method is adopted by carrying out 6 Hydrofracturing tests in a borehole comprising sandstone. A high flow rate of 0.00025 m3/s and viscosity 0.001 Pascal second is applied. Later, the fracture simulation was run on 12 core samples collected from the same depths in a lab. The fluid flow rates of 0.0000005–0.0000015 m3/s, viscosity 0.27 Pascal-second, pore pressure of 4 MPa, confining pressures in vertical-12 MPa and horizontal 6, 18, 24, 30 MPa is applied. The fracture traces and the stress results exhibit a difference of 80 to 300 observed in both cases. The major principle stress orientation obtained in the borehole is 20 and 40. In lab tests with confining horizontal pressures at 6 and 18 MPa, it is 120 and 130, and at 24 and 30 MPa is 20. This indicated that there is fracture delineation occurred. It is observed in the higher flow rate and confining pressures.