Chapter 3 Geological aspects of petroleum related rock mechanics

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

doi:10.1016/s0376-7361(07)53003-7

Cited by 66 publications

(47 citation statements)

References 25 publications

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“…Following the arguments of Chapman et al, the S-wave velocity also has attenuation and dispersion. This is because some of the cracks will necessarily have an orientation such that they will be compressed due to applied shear stress [47]. The attenuation of S-wave velocity is smaller than that of P-wave velocity in the Chapman model.…”

Section: Dispersion and Attenuation Analysis Of Elasticmentioning

confidence: 97%

Fluid Discrimination Based on Frequency-Dependent AVO Inversion with the Elastic Parameter Sensitivity Analysis

Wang

Chen

et al. 2019

Geofluids

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Fluid discrimination is an extremely important part of seismic data interpretation. It plays an important role in the refined description of hydrocarbon-bearing reservoirs. The conventional AVO inversion based on Zoeppritz’s equation shows potential in lithology prediction and fluid discrimination; however, the dispersion and attenuation induced by pore fluid are not fully considered. The relationship between dispersion terms in different frequency-dependent AVO equations has not yet been discussed. Following the arguments of Chapman, the influence of pore fluid on elastic parameters is analyzed in detail. We find that the dispersion and attenuation of Russell fluid factor, Lamé parameter, and bulk modulus are more pronounced than those of P-wave modulus. The Russell fluid factor is most prominent among them. Based on frequency-dependent AVO inversion, the uniform expression of different dispersion terms of these parameters is derived. Then, incorporating the P-wave difference with the dispersion terms, we obtain new P-wave difference dispersion factors which can identify the gas-bearing reservoir location better compared with the dispersion terms. Field data application also shows that the dispersion term of Russell fluid factor is optimal in identifying fluid. However, the dispersion term of Russell fluid factor could be unsatisfactory, if the value of the weighting parameter associated with dry rock is improper. Then, this parameter is studied to propose a reasonable setting range. The results given by this paper are helpful for the fluid discrimination in hydrocarbon-bearing rocks.

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Section: Dispersion and Attenuation Analysis Of Elasticmentioning

confidence: 97%

Fluid Discrimination Based on Frequency-Dependent AVO Inversion with the Elastic Parameter Sensitivity Analysis

Wang

Chen

et al. 2019

Geofluids

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“…To validate the model established above, comparisons of the breakdown pressure between the analytical solutions and the numerical simulation results are shown in Table 2. The analytical solution was calculated using a previously reported theoretical formula (Fjar et al., 2008) …”

Section: Modeling Approachesmentioning

confidence: 99%

Effect of matching relation of multi-scale, randomly distributed pores on geometric distribution of induced cracks in hydraulic fracturing

Peng

2020

Energy Exploration & Exploitation

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Reservoir rock contains many multi-scale, unevenly distributed pores, and the pore structures of shale in different reservoirs and geological environments vary greatly. Because the seepage velocity and pressure field are related to the pore spatial variations, the inhomogeneity of the seepage is superimposed on the anisotropy of the rock’s physical properties, which will affect the distribution of the induced cracks. A method for calculating the pore size in the bonded particle model, based on Delaunay triangulation, is proposed. A modeling approach capable of simulating the multi-scale pore distribution of actual rock is presented based on the proposed method. To understand how microcracks connect micropores in the process of fracturing, several bonded particle model samples with different pore structures were established, and numerical experiments were conducted based on the coupling calculation of the discrete seepage algorithm and discrete element method. The focus of this study was on the interactions between the distribution characteristics of multi-scale pores, the specific physical properties of the fracturing fluid, and the distribution differences of the induced cracks caused by the special seepage characteristics when using different fracturing fluids. The numerical results showed that the advantages of supercritical CO2 fracturing are maximized in deep reservoirs (high in-situ stress) and that a suitable in-situ stress condition is required (i.e. a stress ratio close to 1).

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“…Generally, borehole collapse takes place in the minimum horizontal stress direction, θ = π /2 or 3 π /2 [ 12 ]; the borehole stress on minimum horizontal stress direction [ 13 – 20 ] is as follows:

Assume that safe coefficient FS [ 21 ] is as follows:

And let

Replace normal stress σ n as principal stress σ 1 and σ 3 :

Rewrite Mohr-Coulomb criterion [ 21 ]:

…”

Section: Time-dependent Collapse Pressurementioning

confidence: 99%

Chemical Effect on Wellbore Instability of Nahr Umr Shale

Yan

Nie³

2013

The Scientific World Journal

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Wellbore instability is one of the major problems that hamper the drilling speed in Halfaya Oilfield. Comprehensive analysis of geological and engineering data indicates that Halfaya Oilfield features fractured shale in the Nahr Umr Formation. Complex accidents such as wellbore collapse and sticking emerged frequently in this formation. Tests and theoretical analysis revealed that wellbore instability in the Halfaya Oilfield was influenced by chemical effect of fractured shale and the formation water with high ionic concentration. The influence of three types of drilling fluids on the rock mechanical properties of Nahr Umr Shale is tested, and time-dependent collapse pressure is calculated. Finally, we put forward engineering countermeasures for safety drilling in Halfaya Oilfield and point out that increasing the ionic concentration and improving the sealing capacity of the drilling fluid are the way to keep the wellbore stable.

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Chapter 3 Geological aspects of petroleum related rock mechanics

Cited by 66 publications

References 25 publications

Fluid Discrimination Based on Frequency-Dependent AVO Inversion with the Elastic Parameter Sensitivity Analysis

Fluid Discrimination Based on Frequency-Dependent AVO Inversion with the Elastic Parameter Sensitivity Analysis

Effect of matching relation of multi-scale, randomly distributed pores on geometric distribution of induced cracks in hydraulic fracturing

Chemical Effect on Wellbore Instability of Nahr Umr Shale

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