Distinctive Flow Regions in Crossform Fracture Model in Shale Gas Reservoir Using Numerical Density Derivative Part 3

Pressure transient analysis (PTA) is the industry’s most recognized and acceptable method for assessing well deliverability, skin, nearwellbore permeability and characterize reservoir heterogeneities for hydraulically fractured wells. For these wells, several flowing regions may occur in or around due to the 3D nature of formations flow geometry for which the radial flow symmetry do not often exists. These flow regions are difficult to define by basis of pressure transient data because of near wellbore and formation factors, such as penetration ratio (the ratio of the fractures height to the formation height), inclination angle from the vertical direction, the spacing between fractures, heterogeneities such as vertical and horizontal permeability’s and anisotropy. These parameters influence the well sand face pressure and derivative response.

Since early seventies, PTA industry’s experts and researchers have developed several models considering different well, reservoir and boundaries conditions to describe the pressure transient behavior with or without hydraulic fractures in vertical or horizontal wells. These models were developed based on the source solution and Green’s function to solve unsteady-state flow problem in the reservoir which was presented by Gringarten and Ramey. Also, the Newman product method and source function have been used for solving transient flow problem interpreting pressure behaviors.

Cinco-Ley et al. developed the concept of finite flow capacity and applied semi analytical approach to illustrate the importance of finite fracture when the FCD<300 which is similar to long fractures and low capacity fractures. Their idea facilitated the evaluation of massive hydraulic fracturing programs, although with limitation applicable to systems with small, constant compressibility. Also, their type curve is presently the reference for data analysis from a constant-rate flow test or a pressure-build-up test, depicting vertical hydraulic fracture model in an infinite-acting reservoir. In their study, they introduced a relationship between dimensionless time and pressure behavior which depends on time, and dimensionless fracture conductivity, FCD: