Laboratory-based mathematical modelling of graded proppant injection in CBM reservoirs

Keshavarz, Alireza; Yang, Yumeng; Badalyan, Alexander; Johnson, Raymond L.; Bedrikovetsky, Pavel

doi:10.1016/j.coal.2014.10.005

Cited by 83 publications

(24 citation statements)

References 37 publications

(45 reference statements)

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“…In addition, stress causes prolonged deformation due to creep effect -resulting in sustained variation in permeability (Zhu et al, 2011); (2) Gas adsorption/desorption -adsorption/desorption causes coal matrix to shrink/expand resulting in permeability variation (Pan and Connell, 2012;Zhou et al, 2013); (3) Salt and mineral dissolution and precipitation -the dissolution and precipitation of salts and minerals may alter the flow path to affect the permeability. Decrease in coal seam pressure during CSG production reduces the solubility of carbonate in water and results in the carbonate precipitation (Connell et al, 2008;Moghadasi et al, 2007); and (4) Fines migration -fines are mobilized during flow and may cause blockage of flow path resulting in permeability decrease (Gash, 1991;Keshavarz et al, 2014).…”

Section: Introductionmentioning

confidence: 97%

Permeability variation associated with fines production from anthracite coal during water injection

Guo

Hussain

Cinar

2015

International Journal of Coal Geology

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Section: Introductionmentioning

confidence: 97%

Permeability variation associated with fines production from anthracite coal during water injection

Guo

Hussain

Cinar

2015

International Journal of Coal Geology

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“…The method of natural cleat system stimulation by graded proppant injection has been proposed recently (Bedrikovetsky et al, 2012;Keshavarz et al, 2014a;Keshavarz et al, 2014b;Khanna et al, 2013). The purpose of the graded proppant injection into a natural cleat is keeping it open during the production, where the pore pressure declines with time.…”

Section: Introductionmentioning

confidence: 99%

A New Technique for Enhancing Hydraulic Fracturing Treatment in Unconventional Reservoirs

et al. 2015

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A physical model and experimental data supporting the technology and benefits of graded proppant injection into naturally fractured reservoirs to stimulate natural fracture permeability has been developed recently. In this study, the graded proppant injection has been coupled with hydraulic fracturing treatment for enhancing conductivity of micro-fractures and cleats around the hydraulically induced fractures in coal bed methane reservoirs. In this technique, placing ultra-fine proppant particles in natural fractures and cleats around hydraulically induced fractures at leak-off conditions keeps the coal cleats open during water-gas production and consequently increases the efficiency of hydraulic fracturing treatment.Experimental studies and mathematical modelling for stimulation of natural cleat system around the main hydraulic fracture are conducted. In the laboratory study, core flooding tests are performed to inject flow of suspended particles inside the natural fractures of a coal sample. By placing different particle sizes and evaluating concentration of placed particles, an experimental coefficient is found for optimum proppant placement in which the maximum permeability is achieved after proppant placement. In the mathematical modelling study, a laboratory based mathematical model for graded peroppant placement in naturally fractured rocks around a hydraulically induced fracture is proposed. Derivations of the model include exponential form of the pressure-permeability dependence and accounts for permeability variation in the non-stimulated zone. The explicit formulae are derived for well productivity index by including the experimentally found coefficient.Particle placement tests result in almost three times increase in coal permeability. The laboratory-based mathematical modelling as performed for the field conditions shows that the proposed method yields around 6-times increase in productivity index.

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“…A recently proposed technique for stimulation of natural fracture system is the graded proppant particle injection (Bedrikovetsky et al 2012, Khanna et al 2013, Keshavarz et al 2014a, Keshavarz et al 2014b. The purpose of the proppant injection into a natural cleat is keeping it open during the production, where the pore pressure declines with time.…”

Section: Introductionmentioning

confidence: 99%

Graded Proppant Injection into Coal Seam Gas and Shale Gas Reservoirs for Well Stimulation

et al. 2015

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Low productivity indices are observed in many moderate-to low-permeability coal bed methane (CBM) and shale gas (SG) reservoirs due to low aperture and poor connectivity of natural cleats.A method is proposed for injection of graded proppant particles into a cleat system below the fracturing pressure to keep coal cleats and shale fractures open during water-gas production. Graded proppant injection in CBM and SG reservoirs can: stimulate a stress sensitive cleat system below the fracturing pressure; enhance fracturing treatment by invading cleats, lowering fluid leak-off, and maintaining aperture during production; and provide a periodic or remedial treatment to counter effective stress on the cleats improving production by maintaining cleat aperture.Laboratory tests on bituminous coal core flooding with water under increasing pore pressure with graded proppant injection at the maximum pore pressure (minimum effective stress) have been carried out at different ionic strengths and high pH of the injected water. Proppant particles penetrate deeper into coal matrix at low ionic strength of injected water corresponding to electrostatic particle-particle and particlecoal repulsion. No particle agglomeration and formation of particle-formed cake at the entrance of coal cleats are observed at these conditions. Coal permeability increases by about 2.2 times as the result of a single-sized small particle injection. Followed injection of larger particles leads to a greater enhancement of coal core permeability. An overall increase of coal core permeability after graded proppant injection is about 2.7 times.The proposed method can significantly increase very low productivity index in stress sensitive coals and shales without hydraulic fracturing. It can be also used as a non-damaging leak-off additive during hydraulic fracturing stimulation treatments and to aid long-term conductivity.

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Laboratory-based mathematical modelling of graded proppant injection in CBM reservoirs

Cited by 83 publications

References 37 publications

Permeability variation associated with fines production from anthracite coal during water injection

Permeability variation associated with fines production from anthracite coal during water injection

A New Technique for Enhancing Hydraulic Fracturing Treatment in Unconventional Reservoirs

Graded Proppant Injection into Coal Seam Gas and Shale Gas Reservoirs for Well Stimulation

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