An upscaled transport model for shale gas considering multiple mechanisms and heterogeneity based on homogenization theory

Fan, Weipeng; Sun, Hai; Ye, Jun; Fan, Dongyan; Yang, Yongfei

doi:10.1016/j.petrol.2019.106392

Cited by 10 publications

(11 citation statements)

References 60 publications

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“…With the huge increasing demand of energy, tight oil and gas resources have been playing critical roles in the petroleum industry, especially in China where the tight oil and gas reservoirs make up of more than two thirds of the newly proved reserves 1‐4 . According to the national standard of China (GB/T 34906‐2017 Geological evaluating methods for tight oil), the general definition for tight oil is the petroleum reserved in tight sandstones or carbonates with gas permeability less than 1 × 10 −3 μm 2 (or in situ matrix permeability less than 0.1 × 10 −3 μm 2 ) 5‐7 .…”

Section: Introductionmentioning

confidence: 99%

Accurate characterization of full pore size distribution of tight sandstones by low‐temperature nitrogen gas adsorption and high‐pressure mercury intrusion combination method

Fang

et al. 2020

Energy Science & Engineering

104

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The full pore size distribution represents the integrated characteristics of micro‐nano pore‐throat systems in tight reservoirs. And it involves experiments of different scales to fully analyze the microscope properties. In this paper, we established a new approach for full pore size characterization through conducting the high‐pressure mercury intrusion (HPMI) experiments and low‐temperature nitrogen gas adsorption (LTN2GA) experiments. Meanwhile, we studied the petrology feature of the tight sandstones through X‐ray diffraction (X‐rD) and TESCAN Integrated Mineral Analyzer (TIMA). Then, we investigated the HPMI capillary pressure curves and pore size distribution characteristics, as well as the adsorption‐desorption isotherms features and BET‐specific surface area. Finally, the BJH, non‐local density functional theory (NLDFT) and the quenched solid density functional theory (QSDFT) are contrasted for analyzing the adsorption and pore size distribution characteristics. The HPMI method characterizes the macropores distribution accurately, and the micro/mesopores take up of 14.47% of the total pore spaces. The physisorption isotherms take on the combining shape of type II and IV(a), and the hysteresis loops are like type H3 combined with H4. The BET‐specific surface area is inversely proportional to permeability, and the constant of adsorption heat shows consistence with the analysis results of mineral content. QSDFT can characterize the pore size distribution of micro/mesopores more accurately than the BJH, HPMI, and NLDFT method. By combining the pores narrower than 34 nm calculated from QSDFT method and pores larger than 34 nm calculated from HPMI data with mercury intrusion pressure lower than 42.65 MPa, the full pore size distribution features of tight sandstones are accurately characterized. The micro/mesopores from the new combination method are 3.72% more than that calculated from the HPMI data, and it is of great significance for the accurate pore distribution evaluation and development of tight reservoirs.

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Section: Introductionmentioning

confidence: 99%

Accurate characterization of full pore size distribution of tight sandstones by low‐temperature nitrogen gas adsorption and high‐pressure mercury intrusion combination method

Fang

et al. 2020

Energy Science & Engineering

104

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“…With the increase in energy demand and the decrease in conventional resources, shale gas has recently drawn great attention worldwide. − The economical production of shale gas has been partially realized through horizontal drilling , and hydraulic fracturing. − After hydraulic fracturing, shale gas reservoirs usually possess a multiscale pore structure − (i.e., microscale inorganic matter and kerogen, mesoscale natural fractures, and macroscale hydraulic fractures) and become highly heterogeneous and stress-sensitive . In addition, the gas transport in shale reservoirs is further complicated by some coexisting nonlinear mechanisms, − namely, surface diffusion, Knudsen diffusion, viscous flow, adsorption/desorption, and matrix/fracture deformations due to stress change.…”

Section: Introductionmentioning

confidence: 99%

“…Different from conventional reservoirs, Darcy’s law, which considers only viscous flow, cannot adequately describe the gas flow in the shale matrix because of its extremely small pore size . To quantify the gas-flow mechanisms in micronanopores, various apparent permeability models have been incorporated into Darcy’s equation, such as the Civan model, − the Javadpour model, − and the Dusty-Gas model. − On the contrary, gas transport and storage in kerogen are different from those in inorganic matter, and the local spatial heterogeneity of kerogen further adds complexities to gas transport in shale matrix. − In this context, some upscaling methods have been used to develop the apparent permeability model, in which the local spatial heterogeneity of kerogen and different gas-flow mechanisms in kerogen and inorganic matter are incorporated.…”

Section: Introductionmentioning

confidence: 99%

Hierarchical Modeling of Hydromechanical Coupling in Fractured Shale Gas Reservoirs with Multiple Porosity Scales

et al. 2021

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The simulation of gas flow in shale formation has been a major challenge in the oil and gas industry due to related multiscale pore structure and nonlinear coupled processes such as rock deformation. In this Article, we present a new hierarchical approach for simulating hydromechanical (HM) coupling in fractured shale gas reservoirs with multiple porosity scales, which include microscale inorganic matter and organic matter (kerogen), mesoscale natural fractures, and macroscale hydraulic fractures. Specifically, an equivalent mesoscopic model is developed to represent the inorganic matter and kerogen by using the homogenization method; then, we combine this model with natural fractures and further homogenize them to form the equivalent macroscopic model. In other words, kerogen, inorganic matter, and natural fractures are represented implicitly through the equivalent continuum model, which is developed by using two-level homogenization. On the contrary, we apply the embedded discrete fracture model to explicitly consider hydraulic fractures. After that, the mimetic finite difference method and the stabilized extended finite element method are adopted for the discretization of flow and geomechanics models. Then, the HM coupling model is solved by using a sequential implicit method. Finally, we test the proposed approach by means of some numerical examples and then apply this hierarchical approach to study the effects of inorganic matter, kerogen, natural fractures, and hydraulic fractures on gas production in 3D fractured shale reservoirs.

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“…Compared with conventional reservoirs, tight oil reservoirs are characterized by more heterogeneous matrix, more complicated pore structures, much lower porosity and permeability [3,4]. Thus, conventional flow mathematics models based on Darcy's law are no longer valid [5,6]. The microscopic pore structure of a tight reservoir determines its macroscopic properties and flow law and it has typical multi-scale characteristics [7].…”

Section: Introductionmentioning

confidence: 99%

The Influence of Micro-Fractures on the Flow in Tight Oil Reservoirs Based on Pore-Network Models

et al. 2019

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In this paper, the influence of micro-fractures on the flow of tight reservoirs is studied on the microscopic scale. Three-dimensional digital cores of fractured tight sandstone with varying fracture apertures, lengths, and dip angles are constructed using computed tomography (CT) scans. Pore-network models are built using the three-dimensional digital cores to simulate the flow in tight oil reservoirs. The effects of the micro-fracture aperture, length and dip angle on the pore-throat structure, single-phase flow, and two-phase flow for fracture surfaces with/without roughness are studied. The study demonstrates different influences of micro-fracture characteristics on the flow, and the fracture aperture has the most critical effect. Meanwhile, the roughness of the micro-fracture makes a difference in addition to the three factors of micro-fractures. This paper provides a theoretical basis for the effective development of tight sandstone reservoirs.

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An upscaled transport model for shale gas considering multiple mechanisms and heterogeneity based on homogenization theory

Cited by 10 publications

References 60 publications

Accurate characterization of full pore size distribution of tight sandstones by low‐temperature nitrogen gas adsorption and high‐pressure mercury intrusion combination method

Accurate characterization of full pore size distribution of tight sandstones by low‐temperature nitrogen gas adsorption and high‐pressure mercury intrusion combination method

Hierarchical Modeling of Hydromechanical Coupling in Fractured Shale Gas Reservoirs with Multiple Porosity Scales

The Influence of Micro-Fractures on the Flow in Tight Oil Reservoirs Based on Pore-Network Models

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