Use of Corner Point Geometry in Reservoir Simulation

1995 ◽  
Author(s):  
Y. Ding ◽  
P. Lemonnier
Keyword(s):  
Reservoir Simulation ◽  
Corner Point

Development of an Embedded Discrete Fracture Model for Field-Scale Reservoir Simulation With Complex Corner-Point Grids

SPE Journal ◽  
2019 ◽  
Vol 24 (04) ◽  
pp. 1552-1575 ◽  
Author(s):  
Yifei Xu ◽  
Kamy Sepehrnoori
Keyword(s):  
Case Studies ◽  
Reservoir Simulation ◽  
Corner Point ◽  
Slight Modification ◽  
Fracture Model ◽  
Hydraulic Fractures ◽  
Field Scale ◽  
Discrete Fracture Model ◽  
Model Complex ◽  
Discrete Fracture

Summary Corner-point grids have the capability to model complex geological features, such as faults and irregular reservoir boundaries. As an industry standard, they are widely used to simulate different types of reservoirs, including conventional and unconventional reservoirs. It is necessary to effectively simulate natural or hydraulic fractures in such reservoirs. In this work, a discrete fracture model is developed to conveniently simulate fractures in geologically complex reservoirs represented by corner-point grids. The method is an extension of the embedded discrete fracture model (EDFM). We first present the difficulties in terms of geometrical calculations pertaining to corner-point grids, including the irregularity and degeneracy of block geometry and irregular connections between fracture segments. A general-purpose geometrical algorithm is developed to find the intersections between the matrix and fractures in corner-point grids. This algorithm properly handles the intersection between a general polyhedron and a general polygon, in which both the polyhedron and the polygon can be convex or concave. Transmissibility-factor formulations are also further developed for connections and intersections between fractures. The calculation of effective well indices in different situations is also discussed in detail. Several case studies are presented to illustrate the accuracy and applicability of the developed model in standard black-oil or compositional simulators. The accuracy of the developed model is demonstrated by comparing its simulation results with those of local-grid-refinement (LGR) models. It is also found that the accuracy of the EDFM is not sensitive to matrix gridding when the average size of gridblocks is similar. Field-scale studies using synthetic and realistic reservoir models are presented to illustrate the significance of fractures during secondary recovery. Existing simulators can directly be used in conjunction with the proposed approach with slight modification in simulation input, if the simulators have nonneighboring-connection (NNC) functionality. Through the case studies, the algorithms and methodology developed in this work are shown to be highly effective for the modeling of fractures in field-scale reservoir-simulation studies with complex corner-point grids.

Embedded discrete fracture modeling for compositional reservoir simulation using corner-point grids

2019 ◽  
Vol 177 ◽  
pp. 41-52 ◽  
Author(s):  
Yifei Xu ◽  
Bruno Ramon Batista Fernandes ◽  
Francisco Marcondes ◽  
Kamy Sepehrnoori
Keyword(s):  
Reservoir Simulation ◽  
Corner Point ◽  
Fracture Modeling ◽  
Discrete Fracture

scholarly journals Waterflood Management Using Hybrid Approach of Streamline-Based Interwell Flux Information and Finite Volume Reservoir Simulation

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Zhouyuan Zhu ◽  
Zhengdong Lei ◽  
Zhangxin Chen
Keyword(s):  
Finite Volume ◽  
Oil Recovery ◽  
Reservoir Simulation ◽  
Corner Point ◽  
Hybrid Approach ◽  
Management Program ◽  
Diagnostic Tools ◽  
Streamline Tracing ◽  
Reservoir Simulator ◽  
Injection Rates

In this work, we implement new software for improved waterflood management by combining classical finite volume reservoir simulation together with streamline tracing and corresponding interwell flux evaluations to optimize waterflood performance. We have introduced two basic modules here: a commercial reservoir simulator and our own streamline tracing and waterflood management program. Waterflood simulation is performed for a certain time span until simulation is paused, and the streamline tracing program is called to calculate interwell fluxes and adjust new well rates for better waterflood performance. The simulation continues afterwards until the next tracing and adjustment point is reached. The two modules work iteratively. The streamline tracing program is designed to trace streamlines on a compressible velocity field and a general corner point grid system with nonneighboring connections. The new injection rates are adjusted according to each well's injection efficiency calculated from interwell multi-phase fluxes. Streamline tracing is performed successfully not only on simple geometry corner point grid cases, but also on heavily faulted realistic reservoirs under waterflood. After readjusting injection rates multiple times during the simulation, we typically observe a reduction in field water cut of up to 5% and an increase in oil recovery in our test cases. Interwell flux information serves as effective diagnostic tools to identify injector-producer pairs with large amount of water cycling. All simulations conducted here are rigorously finite volume based, which takes into account the full physics of nonadvective processes such as gravity and capillary effects. In conclusion, we have implemented a streamline‐based waterflood management program which works iteratively and cooperatively with a commercial reservoir simulator, without switching to streamline simulation. It provides an effective solution for improving oil recovery in brown fields by combining the rigorous mathematical nature of finite volume simulation and the power of streamline-based flood management.

COMPARISON OF STRUCTURED CORNER POINT AND UNSTRUCTURED GRIDS FOR COMPOSITIONAL RESERVOIR SIMULATION

2019 ◽  
Author(s):  
Marcelo Menezes Farias ◽  
Thiago Fraxe ◽  
Joaquim Bento Cavalcante Neto ◽  
Francisco Marcondes ◽  
Kamy Sepehrnoori
Keyword(s):  
Reservoir Simulation ◽  
Corner Point ◽  
Unstructured Grids

scholarly journals Dynamic effects of fault modeling on stair-step and corner-point grids

2021 ◽  
Vol 11 (3) ◽  
pp. 1323-1338
Author(s):  
Faruk O. Alpak ◽  
Tianhong Chen
Keyword(s):  
Reservoir Simulation ◽  
Corner Point ◽  
Flow Simulation ◽  
Fault Modeling ◽  
Added Value ◽  
Dynamic Effects ◽  
Flux Approximation ◽  
Grid Convergence ◽  
Simulation Results ◽  
Similar Accuracy

AbstractFault modeling has become an integral element of reservoir simulation for structurally complex reservoirs. Modeling of faults in general has major implications for the simulation grid. In turn, the grid quality control is very important in order to attain accurate simulation results. We investigate the dynamic effects of using stair-step grid (SSG) and corner-point grid (CPG) approaches for fault modeling from the perspective of dynamic reservoir performance forecasting. We have performed a number of grid convergence and grid-type sensitivity studies for a variety of simple, yet intuitive faulted flow simulation problems with gradually increasing complexity. We have also explored the added value of the multipoint flux approximation (MPFA) method over the conventional two-point flux approximation (TPFA) to increase the accuracy of reservoir simulation results obtained on CPGs. Effects of fault seal modeling on grid-resolution convergence and grid-type sensitivity have also been briefly examined. For simple geometries, both SSG and CPG can be used for fault modeling with similar accuracy in conjunction with the pillar-grid approach. This is evidenced by the fact that simulation results from SSG and CPG converge to identical solutions. SSG and CPG yield different results for more complex geometries. Simulation results approach to a converged solution for relatively fine SSGs. However, a SSG only provides an approximation to the fault geometry and reservoir volumes when the grid is coarse. On the other hand, non-orthogonality errors are increasingly evident in relatively more complex faulted models on CPGs and such errors cannot be addressed by grid refinement. It has been observed that MPFA partially addresses the discretization errors on non-orthogonal grids but only from the total flux accuracy perspective. However, transport related errors are still evident. Grid convergence behaviors and grid effects are quite similar with or without fault seal modeling (i.e., dedicated fault-zone modeling by use of scaled-up seal factors) for simple geometries. However, in more complex test cases, we have observed that it is more difficult to achieve converged results in conjunction with fault seal modeling due to increased heterogeneity of the underlying problem.

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