Global Correlation of Rock Brittleness Indices With Petrophysical and Geomechanical Properties and its Application to the Prediction of Rate of Penetration (ROP)

He, Jie; Yu, Claire; Liu, Zhengchun; Samuel, Robello

doi:10.2118/180518-ms

Cited by 4 publications

(2 citation statements)

References 53 publications

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“…Assessing the brittleness of rocks is vitally important for developing unconventional hydrocarbon resources. Brittleness indices can be used to quantify the brittleness of rocks and, on this basis, characterize their fracability (He et al, 2016). However, due to the lack of a standard definition and measurement methods for rock brittleness, researchers have established various brittleness indices for specific practical applications.…”

Section: Brittleness Indicesmentioning

confidence: 99%

“…However, due to the lack of a standard definition and measurement methods for rock brittleness, researchers have established various brittleness indices for specific practical applications. The various definitions to describe rock brittleness are based on the mineral composition (Mathia et al, 2016;Zhang et al, 2017), elastic modulus , σ c and σ t (He et al, 2016), hardness (Lawn and Marshall, 1979), and crack initiation stress of the rock (Wang et al, 2017). In this study, because most of the collected data were related to the strength properties of the SS at the two selected temperatures, we calculated four σ t -and σ cbased brittleness indices (Hucka and Das, 1974;Altindag, 2010) for the SS, as shown below:…”

Section: Brittleness Indicesmentioning

confidence: 99%

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Mechanical Properties of a Typical Jurassic Shaximiao Sandstone Under Subzero and Deep in situ Temperature Conditions

Guan

et al. 2021

Front. Earth Sci.

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Insight into the difference between the mechanical properties of rocks at low and in situ deep reservoir temperatures is vital for achieving a better understanding of fracking technologies with supercritical CO2 and liquid nitrogen. To address this issue, the fracking-related mechanical properties of the Shaximiao Formation sandstone (SS) were investigated through direct tension, uniaxial compression, and three-point bending fracture tests at a typical low temperature (Tlow) of −10°C and a reservoir temperature (Tin situ) of 70°C. The results showed that the tensile strength σt, compressive strength σc, and fracture toughness KIC of the SS were all higher at Tlow than at Tin situ, although to different extents. The KIC of the SS increased slightly more than σt at the lower temperature, while both σt and KIC of the SS increased significantly more than σc at the lower temperature. In addition to the strength, the stiffness (particularly the tensile stiffness) and the brittleness indices of SS were similarly higher at Tlow than at Tin situ. In situ monitoring using the digital image correlation technique revealed that a highly strained band (HSB) always appeared at the crack front. However, because of the inhomogeneous microstructure of the SS, the HSB did not always develop along the line connecting the notch tip to the loading point. This was a possible cause of the highly dispersed KIC values of the SS. The HSB at the crack front was notably narrower at Tlow than at Tin situ, suggesting that low temperatures suppress the plastic deformation of rocks and are therefore beneficial to reservoir stimulation.

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Section: Brittleness Indicesmentioning

confidence: 99%

Section: Brittleness Indicesmentioning

confidence: 99%

Mechanical Properties of a Typical Jurassic Shaximiao Sandstone Under Subzero and Deep in situ Temperature Conditions

Guan

et al. 2021

Front. Earth Sci.

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Reservoir rock chemo-mechanical alteration quantified by triaxial tests and implications to fracture reactivation

Sun

Espinoza

Balhoff

2018

International Journal of Rock Mechanics and Mining Sciences

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Petrophysical Rock Classification, Permeability Estimation, and Elastic Moduli Assessment in Tight Carbonate Reservoirs: A Case Study in Tarim Field, China

Zhou

Heidari

Zhu

et al. 2017

SPE Eastern Regional Meeting

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Conventional rock classification in carbonate reservoirs typically requires considerable amount of core data, which usually may not be available at the depth resolution required for each target interval. In cases of tight carbonate rocks with extremely low porosity (less than 5% in average) and permeability (less than 0.1 md), a reliable rock classification is essential for well stimulation modeling. Such rock classification should take into account depth-by-depth petrophysical, compositional, and elastic properties of the formation. In this paper, we apply an integrated rock classification technique to enhance (a) well-log-based estimates of petrophysical, compositional, and elastic properties and (b) selection of appropriate candidate zones for acid fracturing treatment design in a tight carbonate reservoir in northern slope of Tazhong Uplift, Tarim Basin, China. We first perform multi-mineral analysis and estimate volumetric concentrations of minerals, porosity, and fluid saturations. Since shear wave sonic logs are not available in most of the wells, we estimate elastic moduli using effective medium models including self-consistent approximation and differential effective medium theory. Corrections including the impact of fluids are developed using Biot-Gassmann fluid substitution. The inputs to the effective medium models include (a) the petrophysical and compositional properties obtained from well logs, (b) bulk and shear moduli for each mineral and fluid component, and (c) shape of rock inclusions (i.e., grains and pores). Core measurements are used for cross validating the well-log-based estimates of elastic moduli and petrophysical properties. Accordingly, we proposed a rock classification technique using unsupervised neural network that integrated depth-by-depth volumetric concentrations of minerals, porosity, and elastic moduli. Finally, we derived permeability models in each rock type and estimated the permeability in the target depth intervals. Variogram analysis on well-log-based estimates of permeability provides correlation lengths as inputs to acid fracturing treatment modeling. We successfully applied the technique introduced here to a challenging tight gas interval of Tarim field in China. The estimated porosity and permeability were in good agreement with laboratory core measurements. The identified rock classes were verified by core samples and thin sections. We estimated elastic moduli with average relative errors of approximately 13% compare to the core measurements. The estimated elastic moduli were used as a key input for modeling of acid-fracturing treatments and improved stimulation success. The rock classification technique introduced here provides important input parameters for well stimulation modeling, gives insight into evaluation of acid fracturing in tight carbonate reservoir, and helps with selection of best candidate zones for acid fracturing treatment design.

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Global Correlation of Rock Brittleness Indices With Petrophysical and Geomechanical Properties and its Application to the Prediction of Rate of Penetration (ROP)

Cited by 4 publications

References 53 publications

Mechanical Properties of a Typical Jurassic Shaximiao Sandstone Under Subzero and Deep in situ Temperature Conditions

Mechanical Properties of a Typical Jurassic Shaximiao Sandstone Under Subzero and Deep in situ Temperature Conditions

Reservoir rock chemo-mechanical alteration quantified by triaxial tests and implications to fracture reactivation

Petrophysical Rock Classification, Permeability Estimation, and Elastic Moduli Assessment in Tight Carbonate Reservoirs: A Case Study in Tarim Field, China

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