An integrated approach of measuring permeability of naturally fractured shale

Jia, Bao; Jin, Lu; Mibeck, Blaise A.F.; Smith, Steven A.; Sorensen, James A.

doi:10.1016/j.petrol.2019.106716

Cited by 14 publications

(8 citation statements)

References 16 publications

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“…Data Processing. In this paper, the method of measuring permeability is the steady-state method to record the pressure difference between the two ends of the coal sample at a constant flow rate [31]. The permeability of coal sample fractures is calculated using Darcy's law.…”

Section: Resultsmentioning

confidence: 99%

Experimental Study on the Damage of Artificial Fracture Permeability in Coal during the Flow Back of Guar-Based Fracturing Fluid

et al. 2020

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After the completion of fracturing operation in coalbed methane (CBM), the fracturing fluid needs to flow back to the ground in time to reduce the damage to the coal reservoir. The damage of guar-based fracturing fluid to the coal reservoir has an adverse effect on the fracturing stimulation. A series of flow experiments were carried out with the unconventional natural gas reservoir damage evaluation equipment. This paper investigates the evolution of fracture permeability in coal samples during the process of hydroxypropyl guar (HPG) fracturing fluid flow back. The experimental results show that the fracturing fluid concentration, proppant type, proppant particle size, and proppant concentration all affect fracture permeability. The high concentration of fracturing fluid caused irreversible damage to fracture permeability of coal samples. With the increase of fracturing fluid concentration, the permeability damage rate increased from 65.31% to 84.57%, and the damage degree was strong. KCL brine flushing can only decrease the damage rate of coal sample fracture permeability within a certain range. The proppant embedment and the generation of pulverized coal exacerbated the damage of fracture permeability. The research results can be beneficial for optimizing the type and performance of fracturing fluid for hydraulic fracturing in CBM reservoir.

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Section: Resultsmentioning

confidence: 99%

Experimental Study on the Damage of Artificial Fracture Permeability in Coal during the Flow Back of Guar-Based Fracturing Fluid

et al. 2020

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“…To ensure that the permeability is measured in fractured shale, the extremely tight shale samples should be processed, prior to the permeability measurement, to artificially create fractures inside the samples. Previous studies often used a single pseudo-fracture by splitting the shale sample to measure the permeability, which leads to several questionable issues [ 19 , 20 ]. For example, the shale sample after splitting is no longer an intact rock, and the real micro-fractures after hydraulic fracturing should be randomly distributed with numerous secondary fractures.…”

Section: Sample Characterization and Methodsmentioning

confidence: 99%

Triaxial testing on water permeability evolution of fractured shale

Wang¹,

Zhang

2021

R. Soc. open sci.

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A sound understanding of the water permeability evolution in fractured shale is essential to the optimal hydraulic fracturing (reservoir stimulation) strategies. We have measured the water permeability of six fractured shale samples from Qiongzhusi Formation in southwest China at various pressure and stress conditions. Results showed that the average uniaxial compressive strength (UCS) and average tensile strength of the Qiongzhusi shale samples were 106.3 and 10.131 MPa, respectively. The nanometre-sized (tiny) pore structure is the dominant characteristic of the Qiongzhusi shale. Following this, we proposed a pre-stressing strategy for creating fractures in shale for permeability measurement and its validity was evaluated by CT scanning. Shale water permeability increased with pressure differential. While shale water permeability declined with increasing effective stress, such effect dropped significantly as the effective stress continues to increase. Interestingly, shale permeability increased with pressure when the pressure is relatively low (less than 4 MPa), which is inconsistent with the classic Darcy's theory. This is caused by the Bingham flow that often occurs in tiny pores. Most importantly, the proposed permeability model would fully capture the experimental data with reasonable accuracy in a wide range of stresses.

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“…Therefore, for helium as the testing fluid, the temperature change caused by the Joule‐Thomson effect will be small and will decline over several seconds if the setup is well thermostated (Hannon, 2020; Jia et al., 2020). To further eliminate the influence of the Joule‐Thomson effect, we only use the pressure data starting from 20 s after the application of the pressure pulse (i.e.,

{t}_{0}

≥ 20s).…”

Section: Physical and Mathematical Modelsmentioning

confidence: 99%

An Early‐Time Solution of Pulse‐Decay Method for Permeability Measurement of Tight Rocks

et al. 2021

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This contribution presents an early‐time solution for permeability evaluation in pulse‐decay tests. A nonlinear governing equation for gas transport in the sample is derived considering the pressure dependence of gas compressibility and Klinkenberg slippage effect, and the early‐time solution is obtained through the integral balance analysis. The permeability coefficient can be determined by the proposed solution through the pressure transients during the early‐time stage of the tests, that is, before the upstream pressure pulse penetrates through the core sample and reaches the downstream side. To test the proposed solution, measurements were performed on a core sample of the Cretaceous Eagle Ford shale, Texas, USA, under different pore and confining pressures. Helium was used as the testing fluid to minimize the Joule‐Thomson effect and adsorption. The experimental results show that the permeability coefficients obtained from this new solution agree well with those from the late‐time solution, and prove our solution accurate and efficient for permeability evaluation. The present approach provides a good supplement to the pulse‐decay method and is suitable for measurements of low‐permeable rocks.

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An integrated approach of measuring permeability of naturally fractured shale

Cited by 14 publications

References 16 publications

Experimental Study on the Damage of Artificial Fracture Permeability in Coal during the Flow Back of Guar-Based Fracturing Fluid

Experimental Study on the Damage of Artificial Fracture Permeability in Coal during the Flow Back of Guar-Based Fracturing Fluid

Triaxial testing on water permeability evolution of fractured shale

An Early‐Time Solution of Pulse‐Decay Method for Permeability Measurement of Tight Rocks

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