A Scalable Massively Parallel Dual-Porosity Dual-Permeability Simulator for Fractured Reservoirs with Super-K Permeability

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractModeling Middle East giant carbonate reservoirs with fractures and super-k conductivity present unique challenges to conventional simulation approaches. Fractures in these giant oil fields can exist as fracture swamp neighboring fault zones. These regional/local fractures can interact with Super-K layers (high permeability stratiform) which form extremely high conductivity to fluid flow. Typically, meaningful simulation for such an oil field requires the use of millions of grid cells involving thousands of wells. These reservoirs are not the classical dual porosity where matrix permeability is poor and does not form a part of the global flow path. Dual porosity dual permeability (DPDP) formulation allowing a flexible regional representation of both single porosity and dual porosity behavior on a cell by cell basis is more suitable.A parallel dual porosity dual permeability simulator has been developed to efficiently solve multi-million grid cell fractured reservoirs problems with super-k fracture permeability. To be effective, the simulator has to engage tens to hundreds of processors in a highly scalable manner. This paper discusses the formulation, the data design and solution procedures involved in this development.The parallelization paradigm is the mixed approach with MPI (Message Passing Interface) and OpenMP (Open Message Passing). These parallelization approaches are open standards supported by most major hardware vendors. This allows for easy portability among various hardware architectures. However, the data design and solution methods discussed herein are amenable to MPI only or other parallelization approaches as well. The mixed paradigm approach is flexible and allows various combination and permutation of MPI processes and OpenMP threads to be used to solve a problem.Results are presented for a multi-million cell fractured reservoir simulation with super-k involving thousands of wells and over 60 years of history match. We present simulation results, computational efficiency and parallel scalability on the IBM Nighthawk II, as well as on the PC Xeon Linux cluster hardware.

Development of a multi-mechanistic, dual-porosity, dual-permeability, numerical flow model for coalbed methane reservoirs

“…Porosity and permeability characteristics of the coal matrix are different from those of the fracture network. This dual-porosity, dual-permeability representation has been implemented in the more recent models of fractured systems (Al-Shaalan et al, 2003;Ayala et al, 2005;Fung and AlShaalan, 2005;Gong et al, 2006) and CBM systems (Reeves and Pekot, 2001;Cicek, 2003). In addition, both the coal matrix and the fracture systems require different relative permeability curves in dual-porosity, dual-permeability coalbed methane modeling.…”

Simulation of Naturally Fractured Reservoirs. State of the Art

“…Recent developments in fractured reservoir simulation concern the possible impact of geomechanical parameters on the fracture flow properties, porosity and permeability (Chen and Teufel, 2000;Bagheri and Settari, 2008), the need of high-performance simulators with the use of parallelization techniques for giant fractured field simulation (Al-Shaalan et al, 2003) and the use of streamlines for waterflood simulations with three forms of the transfer function (Di Donato et al, 2003), and also the implementation of PEBI grids in order to keep a better track of the actual/geological fault/fracture network than conventional dual-porosity models (von Pattay and Ganzer, 2001). …”

The Optimal Design of Hydraulic Fracture Parameters in Fractured Gas Reservoirs with Low Porosity

“…Dual porosity (DP) models/ dual porosity and dual permeability (DPDK) models [1][2][3][4][5][6][7] , single porosity models [8] , and discrete models [9][10][11] are the most commonly used methods for naturally fractured reservoirs. Single porosity models cannot represent the interaction between the fracture and the matrix, and discrete models are time-consuming in setting up hydraulic and natural fractures and of high computational cost.…”