Geological aspects of petroleum related rock mechanics

Fjær, Erling; Holt, R.M.; Horsrud, Per; Raaen, A.M.; Risnes, Rasmus

doi:10.1016/b978-0-12-822195-2.00012-7

Cited by 27 publications

(39 citation statements)

References 31 publications

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“…This indicates that the failure process satisfies the MC criterion, which is the most widely used failure criterion in rock mechanics and rock engineering. 9,38 It also reveals that the failure strength of the Chengkou shale is a linear function of confining pressure. 38 However, sample cls-1-5 is an exception because of its mechanical heterogeneity.…”

Section: Resultsmentioning

confidence: 92%

“…30,31 The MC criterion is very useful for describing the response of brittle rocks, and it represents the linear envelope that is obtained from a plot of the shear strength of rock versus the applied normal stress. 9 This relationship between shear stress and normal stress on the slope is expressed as 9 c tan( )…”

Section: Failure Envelopementioning

confidence: 99%

“…In addition, compressional wave velocity v p can be calculated using rock mechanics parameters. The corresponding expression can be written as 9 v E(1…”

mentioning

confidence: 99%

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Experimental Study on the Failure Mechanisms in Brittle Shales

Wang

et al. 2020

ACS Omega

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The brittle failure of Chengkou shale occurs throughout the exploration and development processes of hydrocarbons. To investigate the failure mechanisms of Chengkou shale and analyze the associated mechanical behavior such as crack initiation, propagation, and coalescence at different stress levels, a series of laboratory experiments were conducted on servo-controlled triaxial cells equipped with ultrasound monitoring. The experimental results show that key mechanical parameters such as peak stress σ p , stress onset of dilation σ ci , and strain at peak stress ε p exhibit nearly linear relationships at various confining pressures. In rock bodies, the wave velocity evolution at different stress levels very consistently reproduces the shape of stress−strain curves, while shear wave velocity v s is more sensitive to crack damage than compressional wave velocity v p . Furthermore, the Hoek−Brown failure criterion has an advantage over the Mohr−Coulomb fracture criterion due to the former's higher correlation coefficient r 2 . The wing crack damage models with sandwiched multilayers help explain the mixed tensile and shear failure mechanisms of Chengkou shale. The experimental results provide significant guidance for optimizing the design of drilling and well completion jobs, especially hydraulic fracturing operations, both in Chengkou shale and in other brittle shales around the world.

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Section: Resultsmentioning

confidence: 92%

Section: Failure Envelopementioning

confidence: 99%

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Experimental Study on the Failure Mechanisms in Brittle Shales

Wang

et al. 2020

ACS Omega

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“…On the other hand, rock failure characteristics show the maximum level of applied stresses before the rock failure occurs and are commonly represented in terms of the tensile strength (TS) and unconfined compression strength (UCS) values. The rock geomechanical parameters are extremely influenced by petrophysical characteristics of specific rock type in terms of pore structure, lithological texture, grain bonding, saturating fluid, and internal frame of rock grains. , …”

Section: Introductionmentioning

confidence: 99%

Role of Rock Saturation Condition on Rock–Mud Interaction: Sandstone Geomechanics Study

Gamal

Elkatatny

2022

ACS Omega

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The rock saturation condition affects the rock elastic and strength characteristics due to the role of fluid−rock interaction. However, the role of this parameter has not been studied well for mud−rock exposure during drilling operations. Hence, this study targets to assess the role of different rock saturation conditions on the rock geomechanics changes during the rock exposure for the drilling fluids. During the drilling operation, the mud filtrate invades the drilled formation pore system and replaces the saturating fluid and consequent alterations occur for the rock elastic moduli and failure properties. The current study employed Berea Buff sandstone rock type with different saturation conditions (brine-saturated, dry, and oil-saturated) to interact with drilling mud (water-based) through the filtration test to mimic the downhole rock−mud exposure under pressure, temperature, and time conditions. Extensive laboratory analysis was accomplished that covered the scratching test to get the strength of rock samples, acoustic data determination, elastic moduli evaluation, and scanning electron microscopy to assess the internal alterations of the rock pore system. The obtained results showed that the oil-saturated sample showed the least filtration characteristics for the rock−mud exposure and the best condition to maintain the rock strength from deterioration compared to the dry and brine-saturated samples. The rock strength showed a weakening behavior for the brinesaturated and dry samples by 5 and 18% respectively, while the oil-saturated sample showed only a 2% strength reduction after the mud exposure. Poisson's ratio showed a 21% increase for the brine-saturated sample and the dry sample showed a small increase from 0.2 to 0.22, while the oil-saturated sample maintains a stable Poisson's ratio at 0.24. Young's modulus showed an increase for the dry and brine-saturated rock samples by 10 and 7%, respectively, while a 25% reduction for the oil-saturated. The spectrometry analysis results showed the internal changes in the rock samples' pore system for the brine-saturated and dry samples, while the oilsaturated sample showed no internal changes that maintain the rock structure and strength after the mud exposure.

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“…Most rocks are anisotropic to some extent. The origin of the anisotropy is always heterogeneities on a smaller scale than the volume under investigation, ranging from layered sequences of different rock types down to molecular configurations (Fjær et al., 2008). In particular, shales often show strong elastic anisotropy that originates from the alignment and platy nature of its constituent minerals, as underpinned by laboratory measurements provided by many authors (e.g., Lozovyi & Bauer, 2019; Szewczyk et al., 2018; Vernik & Nur, 1992; Wang, 2002b).…”

Section: Introductionmentioning

confidence: 99%

Rock Physics Model of Shale: Predictive Aspect

2021

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 A predictive rock model is developed based on the recently published Sayers-den Boer approach and compaction-dependent domain orientation  Anisotropy parameters delta and epsilon can be reasonably estimated from limited information using the model  Optimized parameters based on measured data, interplatelet medium properties, are consistent with the saturated fluid and existing studies Accepted ArticleThis article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as

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Geological aspects of petroleum related rock mechanics

Cited by 27 publications

References 31 publications

Experimental Study on the Failure Mechanisms in Brittle Shales

Experimental Study on the Failure Mechanisms in Brittle Shales

Role of Rock Saturation Condition on Rock–Mud Interaction: Sandstone Geomechanics Study

Rock Physics Model of Shale: Predictive Aspect

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