Shape Factors for Irregularly Shaped Matrix Blocks

Wuthicharn, Katha; Zimmerman, Robert W.

doi:10.2118/148060-ms

Cited by 8 publications

(1 citation statement)

References 19 publications

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“…(16) is not applied to the outermost sub-cells, where iso-potential lines at early-time are close to rectangles. The shape factor has been greatly discussed in the literature (see, for example, Wuthicharn and Zimmerman, 2011), and many choices are possible. (15) is still applied to outermost sub-cells.…”

Section: Matrix-fracture Exchangementioning

confidence: 99%

Numerical Simulation of Low Permeability Unconventional Gas Reservoirs

Ding

Farah

et al. 2014

Day 2 Wed, February 26, 2014

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Unconventional gas resources from tight sand and shale gas reservoirs have received great attention in the past decade and become the focus of the petroleum industry as well as energy resources worldwide, because of their large reserves as well as technical advances in developing unconventional resources. Compared to conventional reservoirs, gas production in ultra-lowpermeability unconventional reservoirs is driven by highly non-linear flow equations and involves many coexisting processes due to the presence of multi-scale fracture networks, and to the heterogeneous nature of a porous/fractured and stress-sensitive rock. Therefore, quantifying flow in unconventional gas reservoirs remains a significant challenge.In this paper, we discuss a mathematical model and a numerical approach for simulating the production of unconventional gas reservoirs, in order to assess well performance and understand the critical parameters that affect gas recovery. Specifically, we consider the flow behavior in a stimulated reservoir volume (SRV) including a tight matrix and multi-scale fracture networks, namely primary hydraulic fractures, induced secondary fractures and micro-fractures. The feasibility and the limits in the use of single-porosity or dual-porosity reservoir models to simulate gas flow in such a system are discussed, and a multiporosity approach is evaluated. The impacts of various physics related to unconventional gas reservoirs, such as adsorption/desorption, Klinkenberg and geomechanical effects, are quantified.This work helps to improve simulation technologies for low-permeability unconventional gas reservoirs. An appropriate modeling approach actually underlies effective simulation tools for quantitative studies of unconventional reservoir dynamics and performance, taking into account multi-scale fracture impacts on gas production, well and stimulation design, and optimal production schedules in field development.

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Section: Matrix-fracture Exchangementioning

confidence: 99%

Numerical Simulation of Low Permeability Unconventional Gas Reservoirs

Ding

Farah

et al. 2014

Day 2 Wed, February 26, 2014

View full text Add to dashboard Cite

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Transient transfer shape factor for fractured tight reservoirs: Effect of the dynamic threshold pressure gradient in unsteady flow

Yin

2020

Energy Science & Engineering

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In fractured tight reservoirs, the seepage capacity of the matrix is poor, and fluid migration mainly depends on matrix/fracture transfer. An accurate understanding of the matrix/fracture flow is the basis of well tests and numerical simulations for tight reservoirs. In this paper, the unsteady flow equation for tight reservoirs is deduced based on the boundary layer theory, which can reflect the effect of the dynamic threshold pressure gradient, and the theoretical flow equation is verified by seepage experiments. Based on the study of the flow equation, the approximate semi‐analytical solution of the matrix/fracture unsteady transfer shape factor and the transfer function for tight reservoirs are established considering the early stage of matrix/fracture transfer (pressure does not propagate to the matrix center) and the late stage of matrix/fracture transfer (pseudo‐steady state). The results show that the shape factor of the tight reservoir is mainly affected by three factors (minimum threshold pressure gradient, static boundary layer thickness, and sensitivity coefficient of the fluid boundary layer), and the theoretical curves show that the intermediate transfer enters the pseudo‐steady state when the dimensionless time reaches approximately 0.14. The higher the minimum threshold pressure gradient is, the larger the transfer shape factor. The larger the static boundary layer thickness is, the larger the transfer shape factor; additionally, the larger the sensitivity coefficient of the fluid boundary layer is, the faster the change rate of the shape factor. Finally, the transfer shape factor is applied to a well test interpretation. Examples prove that the fitting accuracy of the new curve type is improved by 34.2% compared with the curve type for the conventional well test interpretation method.

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