Interpretation of Well Test Analysis Into Reservoir Simulator For a Dual Porosity Model
Most of geothermal reservoirs are observed to be fracture dominated. The fractured systems are usually modeled by means of a dual porosity, where fluids exchange between the high porous matrix blocks and high permeable fracture systems is governed by transfer function. Understanding of the unique reservoir behavior of naturally fractured reservoirs is required. Several paths are available for describing this behavior, this study is focused on well testing as a tool to better understand and describe these types of reservoirs. The goal is to correctly characterize the reservoir properties e.g., the permeability, storativity and interporosity flow.
In well testing, Warren and Root defined a dimensionless storage coefficient or well known as the storativity ratio, ω. Is the ratio of fracture storage to total storage of the formation. If the matrix and fracture compressibilities are assumed equal, then the storativity ratio parameter is a function of the porosity ratio. A second well test parameter derived by Warren and Root is called the matrix to fracture transfer rate referred to as the interporosity flow parameter , λ. It is a measure of the mass transfer rate from the matrix to the fracture network. The interporosity flow parameter is a function of the permeability ratio between the matrix and fracture. Both the dimensionless storativity ratio and interporosity flow parameter are key parameter evaluated by well test. These parameters provide useful information from interpretation of pressure data. The information gained from well testing analysis will influence reservoir simulation.