A multi-continuum multiple flow mechanism simulator for unconventional oil and gas recovery

Li, Xiang; Zhang, Dongxiao; Li, Sanbai

doi:10.1016/j.jngse.2015.07.005

Cited by 53 publications

(33 citation statements)

References 62 publications

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“…Based on the ternary component models of shale solid, numerical simulations are performed with the Unconventional Oil and Gas Simulator (UNCONG) [ Li et al ., ]. The gas pressure gradient is set to 10 Pa/µm along the target direction.…”

Section: Multiscale Gas Transport Simulationmentioning

confidence: 96%

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Multiscale pore structure and its effect on gas transport in organic‐rich shale

Zhao

et al. 2017

Water Resources Research

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A systematic investigation of multiscale pore structure in organic‐rich shale by means of the combination of various imaging techniques is presented, including the state‐of‐the‐art Helium‐Ion‐Microscope (HIM). The study achieves insight into the major features at each scale and suggests the affordable techniques for specific objectives from the aspects of resolution, dimension, and cost. The pores, which appear to be isolated, are connected by smaller pores resolved by higher‐resolution imaging. This observation provides valuable information, from the microscopic perspective of pore structure, for understanding how gas accumulates and transports from where it is generated. A comprehensive workflow is proposed based on the characteristics acquired from the multiscale pore structure analysis to simulate the gas transport process. The simulations are completed with three levels: the microscopic mechanisms should be taken into consideration at level I; the spatial distribution features of organic matter, inorganic matter, and macropores constitute the major issue at level II; and the microfracture orientation and topological structure are dominant factors at level III. The results of apparent permeability from simulations agree well with the values acquired from experiments. By means of the workflow, the impact of various gas transport mechanisms at different scales can be investigated more individually and precisely than conventional experiments.

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Section: Multiscale Gas Transport Simulationmentioning

confidence: 96%

“…The average pressure is kept consistent with the cases at level II. The simulations are carried out with the embedded discrete fracture model (EDFM) in UNCONG [ Li et al ., ]. The results are presented in Figure .…”

Section: Multiscale Gas Transport Simulationmentioning

confidence: 99%

Multiscale pore structure and its effect on gas transport in organic‐rich shale

Zhao

et al. 2017

Water Resources Research

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“…These productive marine shale formations are mainly lower Silurian Longmaxi and Ordovician Wufeng with the burial depth of 2,500 meters and formation temperature of 85 ∘ C. Almost all the wells are hydraulically fractured horizontal wells with multiple transverse fractures. Here, we built a single-well model by using the simulation code UNCONG developed by Li et al [24] as shown in Figure 1, and the key shale reservoir properties are listed in Table 1 for the base model used in the following analyses. All the main formation properties used in this study are collected from well logging and lab experiments in the Fuling shale gas play.…”

Section: Numerical Model Of the Shale Gas Reservoirmentioning

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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“…During the simulation, the pressure gradient is calculated using the pressure variables at the centroids of the matrix grid and the fracture grid. The EDFM loses some accuracy around the fractures because the matrix grid size near the fractures is much larger than the size in DFMs, but the overall simulation results are acceptable compared with results obtained from DFMs (Li et al, ; Moinfar et al, ). Therefore, the EDFM can simulate detailed flow behavior in fractured reservoirs while maintaining computational efficiency, which makes the EDFM one of the most promising fracture models.…”

Section: Introductionmentioning

confidence: 95%

“…The necessity of regridding makes the DFMs even more burdensome in inverse modeling, especially for ensemble based methods, in which a group of realizations are simultaneously updated. Recently, the embedded discrete fracture model (EDFM; Lee et al, ; Li et al, ; Li & Lee, ; Moinfar et al, ) has been proposed and attracted considerable attention. This method models fractures as quadrilateral plates, which are inserted into a structured gridding system representing the matrix.…”

Section: Introductionmentioning

confidence: 99%

Tuning Fractures With Dynamic Data

Yao

Chang

et al. 2018

Water Resources Research

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Flow in fractured porous media is crucial for production of oil/gas reservoirs and exploitation of geothermal energy. Flow behaviors in such media are mainly dictated by the distribution of fractures. Measuring and inferring the distribution of fractures is subject to large uncertainty, which, in turn, leads to great uncertainty in the prediction of flow behaviors. Inverse modeling with dynamic data may assist to constrain fracture distributions, thus reducing the uncertainty of flow prediction. However, inverse modeling for flow in fractured reservoirs is challenging, owing to the discrete and non‐Gaussian distribution of fractures, as well as strong nonlinearity in the relationship between flow responses and model parameters. In this work, building upon a series of recent advances, an inverse modeling approach is proposed to efficiently update the flow model to match the dynamic data while retaining geological realism in the distribution of fractures. In the approach, the Hough‐transform method is employed to parameterize non‐Gaussian fracture fields with continuous parameter fields, thus rendering desirable properties required by many inverse modeling methods. In addition, a recently developed forward simulation method, the embedded discrete fracture method (EDFM), is utilized to model the fractures. The EDFM maintains computational efficiency while preserving the ability to capture the geometrical details of fractures because the matrix is discretized as structured grid, while the fractures being handled as planes are inserted into the matrix grids. The combination of Hough representation of fractures with the EDFM makes it possible to tune the fractures (through updating their existence, location, orientation, length, and other properties) without requiring either unstructured grids or regridding during updating. Such a treatment is amenable to numerous inverse modeling approaches, such as the iterative inverse modeling method employed in this study, which is capable of dealing with strongly nonlinear problems. A series of numerical case studies with increasing complexity are set up to examine the performance of the proposed approach.

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A multi-continuum multiple flow mechanism simulator for unconventional oil and gas recovery

Cited by 53 publications

References 62 publications

Multiscale pore structure and its effect on gas transport in organic‐rich shale

Multiscale pore structure and its effect on gas transport in organic‐rich shale

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

Tuning Fractures With Dynamic Data

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