Well test analysis of naturally fractured gas condensate reservoirs

Approximate equations are presented for evaluation of naturally fractured g as condensate reservoirs represented by dual-porosity models in radial syst ems. The reader is cautioned that this work is in progress. Additional rese arch will help to corroborate and refine these techniques. The solutions ha ve not been published previously in the petroleum engineering literature. The solutions are presented for drawdown and buildup tests. The model assum es flow of gas condensate from a tight matrix into permeable natural fractu res. The fractures conduct the fluids to the wellbore. Preliminary work shows that a conventional crossplot of m(p) vs. time on se milogarithmic coordinates results in approximately two parallel straight li nes with a separation that is related to the storativity ratio between frac tures and matrix. This plot allows determination of key parameters such as absolute permeability, effective permeabilities to oil and gas, skin, stora tivity ratio (omega), fracture porosity (phi(2)), average distance between natural fractures (h(m)), radius of investigation, and extrapolated pressur e (p(i) or p*). In addition the method permits generating a liquid saturati on profile and a general composition profile around the wellbore at shut-in .