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Rock Mechanical Properties and calculations
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Rock mechanical properties
The determination of a reservoir’s mechanical properties is critical to reducing drilling risk and maximizing well and reservoir productivity. Estimates of rock mechanical propertiesare central to the following[1]:
Drilling programsWell placementWellcompletion design
Acoustic logging (/Acoustic_logging) can provide information helpful to determining the mechanical properties of reservoir rock.
Contents
1 Mechanical properties of rock2 Computing mechanical rock properties3 References4 Noteworthy papers in OnePetro5 External links6 See also
Mechanical properties of rock
Mechanical properties include:
Elastic properties (Young’s modulus, shear modulus, bulk modulus, and Poisson’s ratio) [See Stress strain relationships in rocks (/Stress_strain_relationships_in_rocks) forcalculations of these properties]Inelastic properties (fracture gradient and formation strength)
Elasticity is the property of matter that causes it to resist deformation in volume or shape. Hooke’s law describes the behavior of elastic materials and states that for smalldeformations, the resulting strain is proportional to the applied stress.
Stress is the force applied per unit areaStrain is the fractional distortion that results because of the acting forceThe modulus of elasticity is the ratio of stress to strain (/Stress_strain_relationships_in_rocks)
Depending on the mode of the acting geological force and type of geological media the force is acting upon, three types of deformation (/Compressive_strength_of_rocks) can resultas well as three elastic moduli that correspond to each type of deformation.
Young’s modulus, E, is the ratio of uniaxial compressive (tensile) stress to the resultant strainBulk modulus, K, is the change in volume under hydrostatic pressure (i.e., the ratio of stress to strain) (K is the reciprocal of compressibility.)Shear modulus, μ, is the ratio of shearing (torsional) stress to shearing strain.An additional parameter, Poisson’s ratio, σ, is a measure of the geometric change of shape under uniaxial stress.
These four elastic parameters are interrelated such that any one can be expressed in terms of two others and can also be expressed in terms of acousticwave velocity and density(Table 1).
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Table 1
Computing mechanical rock properties
The data needed to compute mechanical rock properties are:
Compressional and shear velocities (/Compressional_and_shear_velocities) (slowness)Density (/Rock_density_and_porosity)
Shear and compressional velocities (/Compressional_and_shear_velocities) are a function of:
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Bulk modulusShear modulusDensity (/Rock_density_and_porosity) of the formation being measured
The Vp/Vs ratio, combined with formation density, ρ, is used to calculate:
Poisson’s ratioYoung’s modulusBulk modulusShear modulus
Whenever possible, logderived, dynamic rock properties should be calibrated to corederived static (laboratory) properties, because the static measurements more accuratelyrepresent the insitu reservoir mechanical properties.[2][3][4][5][6] Rock mechanical properties can be determined using either of the following:
Conventional empirical charts[7]Computer programs
The elastic moduli and Poisson’s ratio are used in a variety of applications.[8] These applications include:
Predictions of formation strength (/Rock_failure_relationships)[9][10][11][12][13]
Well stimulation (fracture pressure and fracture height)[14][15][16][17]
Borehole and perforation stability[18]
Sand production and drawdown limits in unconsolidated formations[19][20][21]
Coal evaluation[22]
Determining the roofrockstrength index for underground mining operations.[23][24]
Rock mechanics applications of modern multipole tools are discussed in the article on Anisotropy analysis (/Anisotropy_analysis).
References
1. ↑ Fjaer, E. et al. 1992. Petroleum Related Rock Mechanics, 1338. Amsterdam: Developments in Petroleum Science No. 33, Elsevier, Amsterdam.2. ↑ Montmayeur, H. and Graves, R.M. 1985. Prediction of Static Elastic/Mechanical Properties of Consolidated and Unconsolidated Sands From Acoustic Measurements: Basic
Measurements. Presented at the SPE Annual Technical Conference and Exhibition, Las Vegas, Nevada, 2226 September 1985. SPE14159MS.http://dx.doi.org/10.2118/14159MS (http://dx.doi.org/10.2118/14159MS)
3. ↑ Montmayeur, H. and Graves, R.M. 1986. Prediction of Static Elastic/Mechanical Properties of Consolidated and Unconsolidated Sands From Acoustic Measurements:Correlations. Presented at the SPE Annual Technical Conference and Exhibition, New Orleans, Louisiana, 58 October 1986. SPE15644MS. http://dx.doi.org/10.2118/15644MS (http://dx.doi.org/10.2118/15644MS)
4. ↑ Holt, R.M., Ingsoy, P., and Mikkelson, M. 1989. Rock Mechanical Analysis of North Sea Reservoir Formations. SPE Form Eval 4 (1): 3337. SPE16796PA.http://dx.doi.org/10.2118/16796PA (http://dx.doi.org/10.2118/16796PA)
5. ↑ Gatens III, J.M., Harrison III, C.W., Lancaster, D.E. et al. 1990. InSitu Stress Tests and Acoustic Logs Determine Mechanical Propertries and Stress Profiles in the DevonianShales. SPE Form Eval 5 (3): 248254. SPE18523PA. http://dx.doi.org/10.2118/18523PA (http://dx.doi.org/10.2118/18523PA)
6. ↑ Yale, D.P. 1994. Static and Dynamic Rock Mechanical Properties in the Hugoton and Panoma Fields, Kansas. Presented at the SPE MidContinent Gas Symposium,Amarillo, Texas, 2224 May 1994. SPE27939MS. http://dx.doi.org/10.2118/27939MS (http://dx.doi.org/10.2118/27939MS)
7. ↑ Kowalski, J.J. 1975. Formation Strength parameters from Well Logs, paper N. Trans., 1975 Annual Logging Symposium, SPWLA, 1–19.8. ↑ Sethi, D.K. 1981. Well Log Applications in Rock Mechanics. Presented at the SPE/DOE Low Permeability Gas Reservoirs Symposium, Denver, Colorado, 2729 May 1981.
SPE9833MS. http://dx.doi.org/10.2118/9833MS (http://dx.doi.org/10.2118/9833MS)9. ↑ Tixier, M.P., Loveless, G.W., and Anderson, R.A. 1975. Estimation of Formation Strength From the MechanicalProperties Log(incudes associated paper 6400 ). J PetTechnol 27 (3): 283293. SPE4532PA. http://dx.doi.org/10.2118/4532PA (http://dx.doi.org/10.2118/4532PA)
10. ↑ Stein, N. 1976. Mechanical Properties of Friable Sands From Conventional Log Data (includes associated papers 6426 and 6427 ). J Pet Technol 28 (7): 757763. SPE5500PA. http://dx.doi.org/10.2118/5500PA (http://dx.doi.org/10.2118/5500PA)
11. ↑ Onyia, E. 1988. Relationships Between Formation Strength, Drilling Strength, and Electric Log Properties. Presented at the SPE Annual Technical Conference andExhibition, Houston, 2–5 October. SPE18166MS. http://dx.doi.org/10.2118/18166MS (http://dx.doi.org/10.2118/18166MS)
12. ↑ Stein, N. 1992. Sonic Log Data Help Determine Formation Strength. Oil & Gas J. (28 December): 96.13. ↑ Raaen, A.M., Hovem, K.A., Joranson, H. et al. 1996. FORMEL: A Step Forward in Strength Logging. Presented at the SPE Annual Technical Conference and Exhibition,
Denver, Colorado, 69 October 1996. SPE36533MS. http://dx.doi.org/10.2118/36533MS (http://dx.doi.org/10.2118/36533MS)14. ↑ Anderson, T. and Walker, T. 1972. Log Derived Rock Properties for Use in Well Stimulation Design. Presented at the Fall Meeting of the Society of Petroleum Engineers of
AIME, San Antonio, Texas, 811 October 1972. SPE4095MS. http://dx.doi.org/10.2118/4095MS (http://dx.doi.org/10.2118/4095MS)15. ↑ Anderson, R.A., Ingram, D.S., and Zanier, A.M. 1973. Determining Fracture Pressure Gradients From Well Logs. J Pet Technol 25 (11): 12591268. SPE4135PA.
http://dx.doi.org/10.2118/4135PA (http://dx.doi.org/10.2118/4135PA)16. ↑ Newberry, B.M., Nelson, R.F., and Ahmed, U. 1985. Prediction of Vertical Fracture Migration Using Compression and Shear Wave Slowness. Presented at the SPE/DOE
Low Permeability Gas Reservoirs Symposium, Denver, Colorado, 19–22 May. SPE13895MS. http://dx.doi.org/10.2118/13895MS (http://dx.doi.org/10.2118/13895MS)17. ↑ Stein, N. 1988. How to Calculate Fracture Pressures from Well Logs. Petroleum Engineer Intl. 60 (8): 36–38.18. ↑ Bruce, S. 1990. A Mechanical Stability Log. Presented at the SPE/IADC Drilling Conference, Houston, Texas, 27 February2 March 1990. SPE19942MS.
http://dx.doi.org/10.2118/19942MS (http://dx.doi.org/10.2118/19942MS)19. ↑ Stein, N. and Hilchie, D.W. 1972. Estimating the Maximum Production Rate Possible from Friable Sandstones Without Using Sand Control. J Pet Technol 24 (9): 1157
1160. SPE3499PA. http://dx.doi.org/10.2118/3499PA (http://dx.doi.org/10.2118/3499PA)20. ↑ Edwards, D.P., Sharma, Y., and Charron, A. 1983. Zones of Sand Production Identified by LogDerived Mechanical Properties—A Case Study, paper S. Trans., 1983
European Formation Evaluation Symposium, SPWLA, London Chapter, 1–23.21. ↑ Ong, S., May, A., George, I. et al. 2000. An Accurate Characterization of Sand Strength in Weak and Unconsolidated Formations Aids Offshore Production Test Designs A
Bohai Bay Case Study. Presented at the International Oil and Gas Conference and Exhibition in China, Beijing, China, 710 November 2000. SPE64738MS.http://dx.doi.org/10.2118/64738MS (http://dx.doi.org/10.2118/64738MS)
22. ↑ Fertl, W.H. and DeVries, M.R. 1997. Coal Evaluation Using Geophysical Well Logs, paper F. Trans., 1997 Formation Evaluation Symposium, Canadian Well LoggingSociety, 1–17.
23. ↑ Bond, L.O., Alger, R.P., and Schmidt, A.W. 1971. Well Log Applications in Coal Mining and Rock Mechanics. Trans., AIME 250: 355–362.24. ↑ Kowalski, J. and Fertl, W.H. 1977. Application of Geophysical Well Logging to Coal Mining Operations. Energy Sources 3 (2): 133–147.
Noteworthy papers in OnePetro
Use this section to list papers in OnePetro that a reader who wants to learn more should definitely read
External links
Use this section to provide links to relevant material on websites other than PetroWiki and OnePetro
See also
Acoustic logging (/Acoustic_logging)
Acoustic logging tools (/Acoustic_logging_tools)
Stress strain relationships in rocks (/Stress_strain_relationships_in_rocks)
Rock failure relationships (/Rock_failure_relationships)
Compressive strength of rocks (/Compressive_strength_of_rocks)
Compressional and shear velocities (/Compressional_and_shear_velocities)
Acoustic velocity dispersion and attenuation (/Acoustic_velocity_dispersion_and_attenuation)
Rock acoustic velocities and porosity (/Rock_acoustic_velocities_and_porosity)
Rock acoustic velocities and pressure (/Rock_acoustic_velocities_and_pressure)
Rock acoustic velocities and temperature (/Rock_acoustic_velocities_and_temperature)
Rock acoustic velocities and insitu stress (/Rock_acoustic_velocities_and_insitu_stress)
PEH:Acoustic Logging (/PEH%3AAcoustic_Logging)
PEH:Rock Properties (/PEH%3ARock_Properties)
Category (/Special%3ACategories): 1.2.3 Rock properties (/Category%3A1.2.3_Rock_properties)
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