Numerical Reservoir Simulation to Optimize Waterflooding in Naturally Fractured Reservoirs
Restricted (Penn State Only)
- Author:
- Alzaabi, Abdulla Saleh
- Graduate Program:
- Energy and Mineral Engineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- September 30, 2024
- Committee Members:
- Shimin Liu, Program Head/Chair
Gregory King, Chair & Dissertation Advisor
Julio Urbina, Outside Unit & Field Member
Eugene Morgan, Major Field Member
John Wang, Major Field Member - Keywords:
- Numerical Reservoir Simulation
Dual-porosity
Naturally Fractured Reservoirs
Waterflood
Well Model - Abstract:
- This research presents the development of a series of Naturally Fractured Reservoir Simulation (NFRS) tools including Dual-Porosity, Single-Permeability (DPSK) with pseudo-steady state inter-porosity fluid transfer, Dual-Porosity, Dual-Permeability (DPDK) with pseudo-steady state inter-porosity fluid transfer, Embedded Discrete Fracture Modeling (EDFM) with Single-Porosity, Single-Permeability (SPSK), DPSK, or DPDK background grids. These represent a wide array of NFRS tools, which among others include: • The DPSK pseudo-steady state formulation (i.e., the classic Warren & Root (1963) idealization.) • The DPDK pseudo-steady state formulation. • EDFM formulation with various background grids. The selection of EDFM with a given background grid can be used for fully transient DPDK, and fully transient Triple-Porosity, Triple-Permeability (TPTK) models. • Horizontal well modeling (Peaceman) with single horizontal or multiple horizontal hydraulic fractures. For the pseudo-steady state DPSK and DPDK formulations, we developed a physics-based well model which is an improvement over the conventional well models used for most NFR simulators. The conventional well models used in all published pseudo-steady state (DPSK/DPDK) are identical to the well models used in SPSK simulators (e.g., Peaceman (1978), Abou-Kassem and Aziz (1985), Babu and Odeh (1989)). The well model developed in this work uses a local triple-porosity simulation grid cell in a global dual-porosity grid to allow for the perforated matrix blocks, non-perforated matrix blocks and fractures, the three porosity systems encountered in perforated simulated blocks in DPSK/DPDK models. The conventional well models consider the entire matrix volume as perforated, while the physics-based well model retains the unique mechanisms of the perforated and non-perforated matrix blocks. For example, the perforated matrix blocks are subject to strong viscous forces due to the presence of the well perforations; while the non-perforated matrix blocks are subject to minimal viscous forces in the absence of these perforations and are dominated by spontaneous imbibition and/or gravity drainage. The conventional well model ignores these differences while the proposed well model retains all relevant physics where they occur. We also use the combined SPSK + EDFM formulation to analyze the fully transient DPDK behavior of conventional and pulsed waterfloods in idealized and non-idealized quarter five-spot patterns. Several alternative pulsed waterflooding scenarios were evaluated. Sensitivity analysis was then performed on the capillary pressure curves, matrix-fracture surface area, matrix rock properties, and fluid properties to determine the mechanisms of improved oil recovery using pulsed waterflooding. We found that incremental oil could be recovered from pulsed waterflooding in fractured reservoirs. The mechanisms for incremental oil recovery in fractured reservoirs were observed to be the longer soak times for capillary imbibition during the injection pulsing and the activation of fractures not in the direct injector-producer path. The longer soak times resulted in additional water entering the rock matrix resulting in slower breakthrough times through the fracture dominated system. In addition, oil entered the fractures from the rock matrix through counter-current flow resulting in higher oil cuts in the fracture system.