A Novel Numerical Pressure Transient Model of the Multi-Fractured Horizontal Well with Nonuniform Gas Production Profile

Nonuniform gas production profile has been observed due to reservoir heterogeneity, different fracturing scale and nonuniform distribution of fractures along horizontal wellbore. Different hydraulic fractures yield unequal contribution to total production rates, and the production rates of some fractures even tend to be zero. The current pressure transient analysis (PTA) methods are hard to solve the above problems. Thus, a numerical PTA model for the multi-fractured horizontal well (MFHW) is developed to characterize the nonuniform gas production profile along horizontal wellbore by considering the reservoir heterogeneity, nonuniform fracture networks, nonuniform fracture aperture, and non-planar fractures. The accuracy and advantages of the new model are verified compared with commercial software (Saphir) and other models. The impact of formation heterogeneity, nonuniform fracture aperture, uneven distribution of fracture conductivity, and nonuniform distribution of fractures on pressure transient behavior are investigated. Results show that pseudo-pressure and its derivative curves move down with the increase of formation permeability near hydraulic fractures compared with homogeneous formation. Flow regimes including fracture linear flow, radial flow, elliptical flow, boundary-dominated flow are significantly influenced by formation heterogeneity. Nonuniform fracture aperture mainly affects the fracture linear flow and radial flow. The pseudo-pressure and its derivative will decrease with the increase of the average fracture aperture. The new model extends the PTA method to estimate gas production profile and provides a new insight for gas production profile identification of the MFHW with low risk and low cost in tight gas reservoirs.