Simulation of Gas Desorption and Geomechanics Effects for Unconventional Gas Reservoirs

Yu, Wei; Sepehrnoori, Kamy

doi:10.2118/165377-ms

Cited by 30 publications

(12 citation statements)

References 28 publications

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“…They are in reasonable ranges according to [2]. It is noted that this study did not investigate other parameters such as bottom-hole pressure, in-situ stress, and gas adsorption parameters, although these parameters are very important to gas production [2,39,40]. This optimization process indicated that the optimization room is relatively small, but sensitivity analysis reveals that matrix diffusion plays an incomparable role in gas production.…”

Section: Optimization Resultsmentioning

confidence: 94%

A Multi-Parameter Optimization Model for the Evaluation of Shale Gas Recovery Enhancement

et al. 2018

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Although a multi-stage hydraulically fractured horizontal well in a shale reservoir initially produces gas at a high production rate, this production rate declines rapidly within a short period and the cumulative gas production is only a small fraction (20-30%) of the estimated gas in place. In order to maximize the gas recovery rate (GRR), this study proposes a multi-parameter optimization model for a typical multi-stage hydraulically fractured shale gas horizontal well. This is achieved by combining the response surface methodology (RSM) for the optimization of objective function with a fully coupled hydro-mechanical FEC-DPM for forward computation. The objective function is constructed with seven uncertain parameters ranging from matrix to hydraulic fracture. These parameters are optimized to achieve the GRR maximization in short-term and long-term gas productions, respectively. The key influential factors among these parameters are identified. It is established that the gas recovery rate can be enhanced by 10% in the short-term production and by 60% in the long-term production if the optimized parameters are used. Therefore, combining hydraulic fracturing with an auxiliary method to enhance the gas diffusion in matrix may be an effective alternative method for the economic development of shale gas.

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Section: Optimization Resultsmentioning

confidence: 94%

A Multi-Parameter Optimization Model for the Evaluation of Shale Gas Recovery Enhancement

et al. 2018

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“…Extending from a set of diffusivity and displacement based equations [22], the basic fluid flow and geomechanics formulation in this study is shown in Equations (1)-(3). Equation (1) is based on the Darcy's equation as it is used to describe the fluid transport problem in shale reservoirs [23,24]. Equation (2) represents the gas phase pressure This irreversible permeability damage is the hysteresis phenomenon for stress-sensitive permeability.…”

Section: Numerical Solution To the Coupled Flow And Geomechanics Problemmentioning

confidence: 99%

A Study of Nonlinear Elasticity Effects on Permeability of Stress Sensitive Shale Rocks Using an Improved Coupled Flow and Geomechanics Model: A Case Study of the Longmaxi Shale in China

Wei

Wang²,

et al. 2018

Energies

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Gas transport in shale gas reservoirs is largely affected by rock properties such as permeability. These properties are often sensitive to the in-situ stress state changes. Accurate modeling of shale gas transport in shale reservoir rocks considering the stress sensitive effects on rock petrophysical properties is important for successful shale gas extraction. Nonlinear elasticity in stress sensitive reservoir rocks depicts the nonlinear stress-strain relationship, yet it is not thoroughly studied in previous reservoir modeling works. In this study, an improved coupled flow and geomechanics model that considers nonlinear elasticity is proposed. The model is based on finite element methods, and the nonlinear elasticity in the model is validated with experimental data on shale samples selected from the Longmaxi Formation in Sichuan Basin China. Numerical results indicate that, in stress sensitive shale rocks, nonlinear elasticity affects shale permeability, shale porosity, and distributions of effective stress and pore pressure. Elastic modulus change is dependent on not only in-situ stress state but also stress history path. Without considering nonlinear elasticity, the modeling of shale rock permeability in Longmaxi Formation can overestimate permeability values by 1.6 to 53 times.

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“…The shale gas can be adsorbed on the organic matter, and thus the desorption may be crucial for the ultimate gas recovery in shale formation if the organic content in the shale matrix is high [3]. The desorbed gas combined with free gas in intergranular pores needs to transport through the dominant nanopores in the shale matrix.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Influencing Factors on the Well Performance in Shale Gas Reservoir

Dai¹,

Xue²,

Wang³

et al. 2017

Geofluids

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Due to the ultralow permeability of shale gas reservoirs, stimulating the reservoir formation by using hydraulic fracturing technique and horizontal well is required to create the pathway of gas flow so that the shale gas can be recovered in an economically viable manner. The hydraulic fractured formations can be divided into two regions, stimulated reservoir volume (SRV) region and non-SRV region, and the produced shale gas may exist as free gas or adsorbed gas under the initial formation condition. Investigating the recovery factor of different types of shale gas in different region may assist us to make more reasonable development strategies. In this paper, we build a numerical simulation model, which has the ability to take the unique shale gas flow mechanisms into account, to quantitatively describe the gas production characteristics in each region based on the field data collected from a shale gas reservoir in Sichuan Basin in China. The contribution of the free gas and adsorbed gas to the total production is analyzed dynamically through the entire life of the shale gas production by adopting a component subdivision method. The effects of the key reservoir properties, such as shale matrix, secondary natural fracture network, and primary hydraulic fractures, on the recovery factor are also investigated.

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Simulation of Gas Desorption and Geomechanics Effects for Unconventional Gas Reservoirs

Cited by 30 publications

References 28 publications

A Multi-Parameter Optimization Model for the Evaluation of Shale Gas Recovery Enhancement

A Multi-Parameter Optimization Model for the Evaluation of Shale Gas Recovery Enhancement

A Study of Nonlinear Elasticity Effects on Permeability of Stress Sensitive Shale Rocks Using an Improved Coupled Flow and Geomechanics Model: A Case Study of the Longmaxi Shale in China

Analysis of the Influencing Factors on the Well Performance in Shale Gas Reservoir

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