Brittleness of gas shale reservoirs: A case study from the north Perth basin, Australia

Gholami, Raoof; Rasouli, Vamegh; Sarmadivaleh, Mohammad; Minaeian, Vida; Fakhari, Nikoo

doi:10.1016/j.jngse.2016.03.013

Cited by 72 publications

(25 citation statements)

References 45 publications

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“…Second, each mineral is assigned the same weight coefficient, which means that every mineral has the same contribution to rock brittleness. This lacks a sufficient scientific basis because there are apparent mechanical differences for various minerals [22]. Third, this method does not take other affecting factors into account, such as rock porosity and rock texture.…”

Section: Brittleness Indices Attained From Rock Mineral Compositionsmentioning

confidence: 99%

Brittleness Evaluation in Shale Gas Reservoirs and Its Influence on Fracability

Tang

2020

Energies

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The brittleness index (BI) is a key parameter used to identify the desirable fracturing intervals of shale gas reservoirs. Its correlation with fracability is still controversial. There have been a variety of methods proposed that can estimate BI. The brittleness evaluation method based on stress-strain curves according to the energy-balanced law is the most suitable and reliable in this study. Triaxial compression test, optical microscopy and scanning electron microscopy (SEM) observation, and X-ray diffraction analysis (XRD) were performed on nine drill core samples from well SY3 located in the peripheral regions of Sichuan Basin, China. These tests further evaluated several commonly used methods (brittleness indices based on rock elastic parameters, rock mineral compositions) and determined the relationship between brittleness, rock elastic parameters, and the content of minerals. The results obtained indicate that for sedimentary rocks, a higher Young’s modulus reduces the brittleness of rock, and Poisson’s ratio weakly correlates with brittleness. Excessive amounts of quartz or carbonate minerals can increase the cohesiveness of rock, leading to poor brittleness. Furthermore, the most suitable fracturing layers possess a high brittleness index and low minimum horizontal stress.

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Section: Brittleness Indices Attained From Rock Mineral Compositionsmentioning

confidence: 99%

Brittleness Evaluation in Shale Gas Reservoirs and Its Influence on Fracability

Tang

2020

Energies

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“…In recent years, brittleness has become a key parameter in the field of rock mechanics research. [1][2][3][4][5][6][7] Brittleness is a vital component in hydraulic fracturing of unconventional oil and gas reservoirs, enhanced geothermal systems, coal mining, the stability of wellbore walls, and other applications. [8][9][10][11][12][13][14][15] Understanding the essential characteristics of rock brittleness has important academic value.…”

Section: Introductionmentioning

confidence: 99%

A brittleness evaluation method of rock constitutive relationship with Weibull distribution based on double‐body system theory

Zhang

Wang

Ruan

et al. 2020

Energy Science & Engineering

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Brittleness of rocks plays an important role in the evaluation of unconventional oil and gas reservoir network fracturing and many rock engineering application fields. However, there is still no commonly accepted definition of the concept of brittleness. In this study, the brittleness differences between rocks are understood as the differences of internal microunit strength cracking characteristics under an external load. Because rock ruptures are regarded as a fracturing problem of a double body system, the region where no cracking occurs during the uniaxial compression loading process is regarded as a body I system with elastic deformation characteristics; the region that breaks first and induces the integral fracture of the rock is regarded as a body II system in which the structural strength of the microunit follows the deformation characteristic of the Weibull distribution. An energy quasi‐static equilibrium equation for rock fractures of a double body system under an external load was established. A new index for evaluating brittleness was established based on the energy mutation process of the quasi‐static equilibrium equation of double body system. Sandstone, red sandstone, mudstone, sandy mudstone, shale, limestone, and granite were selected as the research objects, while the correlation curve between the new brittleness index, the Weibull distribution characteristic parameters, and the mutation break point was calculated. The brittleness index studied in this paper reveals the evolution process of integral fractures induced by the internal fractures of rocks, which is important for further understanding the essence of brittleness. These results can provide a new method for further studying the formation process of local fracture networks.

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“…As a key factor affecting the morphology of postfracturing network in the shale reservoir, the properties of its basic constituents, specifically the characteristics of brittle minerals, have always been a matter of discussion in the research community. Brittleness indices based on rock composition and the fraction of brittle mineral content were proposed by many researchers [22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Effect of Brittle Mineral Size on Hydraulic Fracture Propagation in Shale Gas Reservoir

Gao

Iqbal

et al. 2019

Geofluids

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The properties of brittle minerals have great effect on the morphology of postfracturing network in shale reservoirs in the southeastern Ordos Basin, China. In order to study the effect of brittle mineral size distributions on the fracture parameters, the concrete cubes of 300 mm × 300 mm × 300 mm in size with four distinct brittle mineral sizes of 2.36 mm, 0.425 mm, 0.15 mm, and 0.075 mm were investigated under large-sized triaxial hydraulic fracturing test. The effect mechanism of aggregate on the fracture properties of shale was studied using ultrasonic technique, photosensitive electron microscope, and numerical simulation. The test results obtained for each specimen (both disturbed and undisturbed conditions) indicate that brittle mineral size has significant effect on the fracture extension. The tensile strength, fracture toughness, and fracture pressure were found to decrease with a decrease in maximum brittle mineral size when the maximum brittle mineral size is smaller than 0.425 mm. In addition to this, the degree of attenuation difference also follows the similar trend. Observed fracture morphology reveals that with an increase in maximum size of brittle mineral specimen, the tortuous and complicated cracking path generation increases. These findings would be very helpful in order to better understand the behavior of shale under hydraulic fracturing test.

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Brittleness of gas shale reservoirs: A case study from the north Perth basin, Australia

Cited by 72 publications

References 45 publications

Brittleness Evaluation in Shale Gas Reservoirs and Its Influence on Fracability

Brittleness Evaluation in Shale Gas Reservoirs and Its Influence on Fracability

A brittleness evaluation method of rock constitutive relationship with Weibull distribution based on double‐body system theory

Effect of Brittle Mineral Size on Hydraulic Fracture Propagation in Shale Gas Reservoir

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