INTERPRETATION OF PRESSURE TESTS IN UNIFORM-FLUX FRACTURED VERTICAL WELLS WITH THRESHOLD PRESSURE GRADIENT IN LOW PERMEABILITY RESERVOIRS

The level of pressure gradient needed to enable fluid to overcome the viscous forces and start flowing is referred to as the threshold pressure gradient, TPG, or minimum pressure gradient required for fluid flow. While it has been observed that TPG has an important effect on the pseudorradial flow regime of a fractured vertical well, the early linear flow regime caused by the fracture is not impacted by TPG. In this work, TDS methodology is implemented for interpretation of pressure tests in uniform-flux fractured vertical wells of low permeability reservoirs affected by TPG. Two governing equations of the TPG effect on pressure response were developed, in addition to two correlations, which were all tested and validated in a synthetic case.