ISRM Suggested Method for Uniaxial-Strain Compressibility Testing for Reservoir Geomechanics

Dudley, J. W.; Brignoli, M.; Crawford, Brian; Ewy, Russell T.; Love, D. K.; McLennan, John; Ramos, Gustavo; Shafer, John; Sharf-Aldin, Munir; Siebrits, E.; Boyer, J.; Chertov, Maxim

doi:10.1007/s00603-016-1055-4

Cited by 40 publications

(21 citation statements)

References 9 publications

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“…In this test, the pore pressure is the controlling parameter. The compressibility terms calculated directly from the test include the bulk compressibility under changing pore‐pressure conditions ( C bp ) and pore compressibility under changing pore‐pressure conditions ( C pp ) 46 . Elastic moduli (Young's modulus and Poisson's ratio) can then be estimated as a function of the two the compressibility terms 46 .…”

Section: Geomechanical Modeling Resultsmentioning

confidence: 99%

The effect of Biot coefficient and elastic moduli stress–pore pressure dependency on poroelastic response to fluid injection: laboratory experiments and geomechanical modeling

2020

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Biot coefficient and elastic moduli are typically assumed to have a constant value for analyzing poroelastic effects of fluid injection. To investigate the stress-pore pressure dependency of Biot coefficient and elastic moduli, we conducted a series of laboratory experiments on a porous dolomite core sample from a reef in Michigan basin. We varied the confining stress as well as the pore pressure in the experiments. Then, modeling was performed using analytical poroelastic solutions and a coupled two-phase flow-geomechanical numerical simulation (for CO 2 injection). The modeling results show that the variability of Biot coefficient and elastic moduli should be included in the geomechanical modeling to accurately predict the poroelastic responses of injection (i.e., stress changes and surface uplift). Using a constant stress-independent Biot coefficient elastic moduli, which is the assumption in poroelastic modeling, leads to underestimation of the stress change and surface uplift due to injection compared to a realistic stress-pore pressure dependent Biot coefficient, which is updated at each time step of injection modeling. Modeling results indicate that decreasing elastic modulus combined with Biot coefficient increase due to the fluid injection could lead to a larger surface uplift and stress changes in the reservoir. In addition, the stress changes and uplift due to injection are a function of initial in situ stress due to Biot coefficient and elastic modulus stress-pore pressure dependency.

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Section: Geomechanical Modeling Resultsmentioning

confidence: 99%

The effect of Biot coefficient and elastic moduli stress–pore pressure dependency on poroelastic response to fluid injection: laboratory experiments and geomechanical modeling

2020

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“…In order to keep the initial state of the coal sample as far as possible, dry drilling, dry cutting and dry grinding under low velocity were used in the process of specimen preparation. There were ten specimens, which met the suggested method of International Society for Rock Mechanics (ISRM) [41,42] after eliminating the coal sample whose surface had evident microcrack. The sizes of the six specimens were both with a diameter of 50 mm and height of 100 mm.…”

Section: Raw Coal Specimensmentioning

confidence: 99%

“…Two standards, i.e., the preparation method of the coal sample (GB 474-2008) [43] and standard test methods for physical and mechanical properties of concrete (GBT2050081-2019) [44] provided reference for the sampling, crushing, screening, preparation and curing of shaped coal specimens. The shape and size met the suggested method of ISRM [41,42]. The coal samples taken in the field were crushed by the pulverizer, and the crushing granularities are respectively 0.50-2.00 mm, 0.25-0.50 mm and less than 0.25 mm.…”

Section: Raw Coal Specimensmentioning

confidence: 99%

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Experimental Investigation on Time-Frequency Characteristics of Microseismic Signals in the Damage Evolution Process of Coal and Rock

Yang

Rui

et al. 2020

Energies

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The deformation and failure of coal and rock materials is the primary cause of many engineering disasters. How to accurately and effectively monitor and forecast the damage evolution process of coal and rock mass, and form a set of prediction methods and prediction indicators is an urgent engineering problems to be solved in the field of rock mechanics and engineering. As a form of energy dissipation in the deformation process of coal and rock, microseismic (MS) can indirectly reflect the damage of coal and rock. In order to analyze the relationship between the damage degree of coal and rock and time-frequency characteristics of MS, the deformation and fracture process of coal and rock materials under different loading modes was tested. The time-frequency characteristics and generation mechanism of MS were analyzed under different loading stages. Meanwhile, the influences of properties of coal and rock materials on MS signals were studied. Results show that there is an evident mode cutoff point between high-frequency and low-frequency MS signals. The properties of coal and rock, such as the development degree of the original fracture, particle size and dense degree have a decisive influence on the amplitude, frequency, energy and other characteristic parameters of MS signals. The change of MS parameters is closely related to material damage, but has no strong relation with the loading rate. The richness of MS signals before the main fracture depends on the homogeneity of materials. With the increase of damage, the energy release rate increases, which can lead to the widening of MS signals spectrum. The stiffness and natural frequency of specimens decreases correspondingly. Meanwhile, the main reason that the dominant frequency of MS detected by sensors installed on the surface of coal and rock materials is mainly low-frequency is friction loss and the resonance effect. In addition, the spectrum and energy evolution of MS can be used as a characterization method of the damage degree of coal and rock materials. Furthermore, the results can provide important reference for prediction and early warning of some rock engineering disasters.

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“…The unconfined compressive strength (UCS) test was carried out on the cement sample according to the ASTM [50] and the ISRM [51] standards. UCS is the rock strength measured when uniaxial loading is applied.…”

Section: Unconfined Compressive Strengthmentioning

confidence: 99%

An Experimental Study to Reduce the Fracture Pressure of High Strength Rocks Using a Novel Thermochemical Fracturing Approach

et al. 2019

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Current oil prices and global financial situations underline the need for the best engineering practices to recover remaining oil from unconventional hydrocarbon reservoirs. These hydrocarbon reservoirs are mostly situated in deep and overpressured formations, with high rock strength and integrity. Breakdown pressure of the rock is a function of their tensile strength and in situ stresses acting on them. Fracturing stimulation techniques become challenging when treating these types of rocks, and many cases approached to the operational limits. This leaves a small operational window to initiate and place hydraulic fractures. In this study, a new methodology to reduce the breakdown pressure of the high stressed rock is presented. The new method enables the fracturing of high stressed rocks more economically and efficiently. Fracturing experiments were carried out on different blocks, and the breakdown pressure was measured by creating a simulated borehole at the center of the block. Thermochemical fluids were injected to create the microfractures. These microfractures improved the permeability and porosity and reduced the elastic strength of the subjected samples prior to the main hydraulic fracturing job. The posttreatment experimental analysis confirmed the presence of microfractures which were originated due to the pressure pulse generated from the thermochemical reaction. The results of this study showed that the newly formulated method of thermochemical fracturing reduced the breakdown pressure by 38% in slim borehole blocks and 60% in large borehole blocks. Results also showed that the breakdown time to initiate the fractures was reduced to 19% in slim borehole blocks and 17% in large borehole blocks. The reduction in breakdown pressure and breakdown time happened due to the creation of microfractures by the pressure rise phenomenon in a new thermochemical fracturing approach.

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ISRM Suggested Method for Uniaxial-Strain Compressibility Testing for Reservoir Geomechanics

Cited by 40 publications

References 9 publications

The effect of Biot coefficient and elastic moduli stress–pore pressure dependency on poroelastic response to fluid injection: laboratory experiments and geomechanical modeling

The effect of Biot coefficient and elastic moduli stress–pore pressure dependency on poroelastic response to fluid injection: laboratory experiments and geomechanical modeling

Experimental Investigation on Time-Frequency Characteristics of Microseismic Signals in the Damage Evolution Process of Coal and Rock

An Experimental Study to Reduce the Fracture Pressure of High Strength Rocks Using a Novel Thermochemical Fracturing Approach

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