Streamline Tracing and Sensitivity Calculation in Fractured Reservoir with Complex Geometry: Field Application to History Matching and Flood Optimization
The popularity of streamline application mainly depends on two aspects: efficient tracing algorithm to generate streamline, and effective flow and transport analysis along streamline. Previous studies proved its applicability for conventional resources such as waterflood in single and dual porosity models. Streamline technology has limited success in extension to fractured reservoir with discrete fracture networks due to lack of efficient tracing method in the complex porous media geometry. Streamline based application such as history matching and rate optimization also has limitation to gas reservoir depletion or fractured reservoir waterflood due to lack of effective streamline-based flow and transport analysis for highly compressible fluid and highly contrasted porous media.
In this study, we first develop streamline tracing method in complex geometry such as faults and discrete fractures. The discrete fractures here are depicted by embedded discrete fracture model (EDFM). We are going to propose novel methods to construct boundary layers for fault non-neighbor connections and EDFM non-neighbor connections. The novel methods reduce the treatment of complex grid geometry to a minimum level and honor the flux of each connection. The utility and validity of this proposed approach is demonstrated using both 2D and 3D examples.
Second, we propose an amended streamline-based travel time sensitivity formulation. This novel sensitivity formulation has improved accuracy than the legacy one when compared to numerical perturbed sensitivity, thus results in faster data misfit reduction. We also develop general streamline-based bottom hole pressure sensitivity
calculation method suitable for highly compressible fluids or complex geometry caused by non-neighbor connections. The bottom hole pressure sensitivity calculation is validated by a successful history matching application to a high pressure high temperature gas reservoir.
Finally, we develop a rate allocation optimization method based on fast estimation of oil recovery, which also applies to fractured reservoirs. The oil recovery is estimated along streamline within the drainage volume by the end of optimization period. The injection/production rates are updated to maximize the field oil recovery. The novel optimization method results in better performance than equalizing well pair injection efficiency or equalizing well pair time of flight when applying to a waterflood case in fractured reservoir. Its validation is further established by the waterflood optimization application to a field scale EDFM reservoir.
We concluded that our proposed approach of streamline tracing, inversion and optimization algorithm extends streamline technology application to fractured media represented by discrete fracture networks and highly compressible fluid, leading to a highly effective reservoir management tool
