Estimating Unpropped-Fracture Conductivity and Fracture Compliance From Diagnostic Fracture-Injection Tests
- HanYi Wang (University of Texas at Austin) | Mukul M. Sharma (University of Texas at Austin)
- Document ID
- Society of Petroleum Engineers
- SPE Journal
- Publication Date
- October 2018
- Document Type
- Journal Paper
- 1,648 - 1,668
- 2018.Society of Petroleum Engineers
- Fracture Conductivity, Fracture Compliance, DFIT, system stiffness, Un-Propped Fracture
- 5 in the last 30 days
- 215 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 10.00|
|SPE Non-Member Price:||USD 30.00|
A new method is proposed to estimate the compliance and conductivity of induced unpropped fractures as a function of the effective stress acting on the fracture from diagnostic-fracture-injection-test (DFIT) data. A hydraulic-fracture resistance to displacement and closure is described by its compliance (or stiffness). Fracture compliance is closely related to the elastic, failure, and hydraulic properties of the rock. Quantifying fracture compliance and fracture conductivity under in-situ conditions is crucial in many Earth-science and engineering applications but is very difficult to achieve. Even though laboratory experiments are used often to measure fracture compliance and conductivity, the measurement results are influenced strongly by how the fracture is created, the specific rock sample obtained, and the degree to which it is preserved. As such, the results may not be representative of field-scale fractures.
During the past 2 decades, the DFIT has evolved into a commonly used and reliable technique to obtain in-situ stresses, fluid-leakoff parameters, and formation permeability. The pressure-decline response across the entire duration of a DFIT reflects the process of fracture closure and reservoir-flow capacity. As such, it is possible to use these data to quantify changes in fracture conductivity as a function of stress. In this paper, we present a single, coherent mathematical framework to accomplish this. We show how each factor affects the pressure-decline response, and the effects of previously overlooked coupled mechanisms are examined and discussed. Synthetic and field-case studies are presented to illustrate the method. Most importantly, a new specialized plot (normalized system-stiffness plot) is proposed, which not only provides clear evidence of the existence of a residual fracture width as a fracture is closing during a DFIT, but also allows us to estimate fracture-compliance (or stiffness) evolution, and infer unpropped fracture conductivity using only DFIT pressure and time data alone. It is recommended that the normalized system-stiffness plot (NS plot) be used as a standard practice to complement the G-function or square-root-of-time plot and log-log plot because it provides very valuable information on fracture-closure behavior and the properties of fracture-surface roughness at a field-scale, information that cannot be obtained by any other means.
|File Size||2 MB||Number of Pages||21|
Barton, N., Bandis, S., and Bakhtar, K. 1985. Strength, Deformation, and Conductivity Coupling of Rock Joints. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 22 (3): 121–140. https://doi.org/10.1016/0148-9062(85)93227-9.
Bhide, R., Gohring, T., McLennan, J. et al. 2014. Sheared Fracture Conductivity. In Proc., 39th Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, California, USA, 24–26 February. SGP-TR-202.
Bryant, E. C., Hwang, J., and Sharma, M. M. 2015. Arbitrary Fracture Propagation in Heterogeneous Poroelastic Formations Using a Finite Volume-Based Cohesive Zone Model. Presented at the SPE Hydraulic Fracturing Technology Conference, The Woodlands, Texas, USA, 3–5 February. SPE-173374-MS. https://doi.org/10.2118/173374-MS.
Economides, M. J. and Nolte, K. G. 2000. Reservoir Stimulation, third edition. Chichester, England; New York: John Wiley.
Evans, K. F., Kohl, T., Rybach, L. et al. 1992. The Effects of Fracture Normal Compliance on the Long-Term Circulation Behavior of a Hot Dry Rock Reservoir: A Parameter Study Using the New Fully-Coupled Code “Fracture”. Geothermal Resources Council, Davis, California, USA, Vol. 16, pp. 449–456.
Fredd, C. N., McConnell, S. B., Boney, C. L. et al. 2000. Experimental Study of Hydraulic-Fracture Conductivity Demonstrates the Benefits of Using Proppants. Presented at the SPE Rocky Mountain Regional/Low-Permeability Reservoirs Symposium and Exhibition, Denver, 12–15 March. SPE-60326-MS. https://doi.org/10.2118/60326-MS.
Gu, H., Elbel, J. L., Nolte, K. G. et al. 1993. Formation Permeability Determination Using Impulse-Fracture Injection. Presented at the SPE Production Operations Symposium, Oklahoma City, Oklahoma, USA, 21–23 March. SPE-25425-MS. https://doi.org/10.2118/25425-MS.
Hopkins, D. L., Cook, N. G., and Myer, L. R. 1987. Fracture Stiffness and Aperture as a Function of Applied Stress and Contact Geometry. Presented at the 28th US Symposium on RockMechanics (USRMS), American RockMechanics Association, Tucson, Arizona, USA, June–1 July. ARMA-87-0673.
Iding, M. and Ringrose, P. 2009. Evaluating the Impact of Fractures on the Long-Term Performance of the In Salah CO2 Storage Site. Energy Procedia 1: 2021–2028. https://doi.org/10.1016/j.egypro.2009.01.263.
Koning, E. J. L. and Niko, H. 1985. Fractured Water-Injection Wells: A Pressure Falloff Test for Determining Fracture Dimensions. Presented at the SPE Annual Technical Conference and Exhibition, Las Vegas, Nevada, USA, 22–26 September. SPE-14458-MS. https://doi.org/10.2118/14458-MS.
McClure, M. W., Babazadeh, M., Shiozawa, S. et al. 2016. Fully Coupled Hydromechanical Simulation of Hydraulic Fracturing in 3D Discrete-Fracture Networks. SPE J. 21 (4):1302–1320. SPE-173354-PA. https://doi.org/10.2118/173354-PA.
Nolte, K. G. 1979. Determination of Fracture Parameters From Fracturing Pressure Decline. Presented at the SPE Annual Technical Conference and Exhibition, Las Vegas, Nevada, USA, 23–26 September. SPE-8341-MS. https://doi.org/10.2118/8341-MS.
Nolte, K. G. 1986. A General Analysis of Fracturing Pressure Decline With Application to Three Models. SPE Form Eval 6: 571–583. SPE-12941-PA. https://doi.org/10.2118/12941-PA.
Pyrak-Nolte, L. J. and Nolte, D. D. 2016. Approaching a Universal Scaling Relationship Between Fracture Stiffness and Fluid Flow. Nature Communications 7. https://doi.org/10.1038/ncomms10663.
Sakaguchi, K., Tomono, J., Okumura, K. et al. 2008. Asperity Height and Aperture of an Artificial Tensile Fracture of Metric Size. Rock Mechanics and Rock Engineering 41 (2): 325–341. https://doi.org/10.1007/s00603-005-0102-3.
Scholz, C. H. 2002. The Mechanics of Earthquakes and Faulting. Cambridge University Press.
Sesetty, V. and Ghassemi, A. 2015. Simulation of Simultaneous and Zipper Fractures in Shale Formations. Presented at the 49th US Rock Mechanics/Geomechanics Symposium, American Rock Mechanics Association, San Francisco, California, USA, 28 June–1 July. ARMA-2015-558.
Sharma, M. M. and Manchanda, R. 2015. The Role of Induced Unpropped (IU) Fractures in Unconventional Oil and Gas Wells. Presented at the SPE Annual Technical Conference and Exhibition, Houston, 28–30 September. SPE-174946-MS. https://doi.org/10.2118/174946-MS.
Soliman, M. Y., Craig, D. P., Bartko, K. M. et al. 2005. Post-Closure Analysis to Determine Formation Permeability, Reservoir Pressure, Residual Fracture Properties. Presented at the SPE Middle East Oil and Gas Show and Conference, Kingdom of Bahrain, 12–15 March. SPE-93419-MS. https://doi.org/10.2118/93419-MS.
van Dam, D. B., de Pater, C. J., and Romijn, R. 2000. Analysis of Hydraulic Fracture Closure in Laboratory Experiments. SPE Prod & Fac 15 (3): 151–158. SPE-65066-PA. https://doi.org/10.2118/65066-PA.
van den Hoek, P. J. 2005. Dimensions and Degree of Containment of Waterflood-Induced Fractures From Pressure-Transient Analysis. SPE Res Eval & Eng 8 (5): 377–387. SPE-84289-PA. https://doi.org/10.2118/84289-PA.
Wang, H. 2015. Numerical Modeling of Non-Planar Hydraulic Fracture Propagation in Brittle and Ductile Rocks Using XFEM With Cohesive Zone Method. Journal of Petroleum Science and Engineering 135: 127–140. https://doi.org/10.1016/j.petrol.2015.08.010.
Wang, H. 2016. Numerical Investigation of Fracture Spacing and Sequencing Effects on Multiple Hydraulic Fracture Interference and Coalescence in Brittle and Ductile Reservoir Rocks. Engineering Fracture Mechanics 157: 107–124. https://doi.org/10.1016/j.engfracmech.2016.02.025.
Wang, H., Marongiu-Porcu, M., and Economides, M. J. 2016. Poroelastic and Poroplastic Modeling of Hydraulic Fracturing in Brittle and Ductile Formations. SPE Prod & Oper 31 (1): 47–59. SPE-168600-PA. https://doi.org/10.2118/168600-PA.
Wang, H. 2017. What Factors Control Shale Gas Production and Production Decline Trend in Fractured Systems: A Comprehensive Analysis and Investigation. SPE J. 22 (2): 562–581. SPE-179967-PA. https://doi.org/10.2118/179967-PA.
Wang, H. and Sharma, M. M. 2017a. A Non-Local Model for Fracture Closure on Rough Fracture Faces and Asperities. Journal of Petroleum Science and Engineering 154: 425–437. https://doi.org/10.1016/j.petrol.2017.04.024.
Wang, H. and Sharma, M.M. 2017b. New Variable Compliance Method for Estimating Closure Stress and Fracture Compliance From DFIT Data. Presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, 9–11 October. SPE-187348-MS. https://doi.org/10.2118/187348-MS.
Wang, H. 2018. Discrete Fracture Networks Modeling of Shale Gas Production and Revisit Rate Transient Analysis in Heterogeneous Fractured Reservoirs. Journal of Petroleum Science and Engineering 169 (October): 796–812. https://doi.org/10.1016/j.petrol.2018.05.029.
Wang, H and Sharma, M. M. 2018. Estimating Fracture Closure Stress in Naturally Fractured Reservoirs With Diagnostic Fracture Injection Tests. Paper ARMA-2018-225 presented at the 52nd US Rock Mechanics/Geomechanics Symposium, Seattle, Washington, 17–20 June.
Wang, H., Yi, S., and Sharma, M. M. 2018. A Computational Efficient Method for Solving Crack Closure and Contact Problems Using Superposition Method. Theoretical and Applied Fracture Mechanics 93: 276–287. https://doi.org/10.1016/j.tafmec.2017.09.009.
Warpinski, N. R., Lorenz, J. C., Branagan, P. T. et al. 1993. Examination of a Cored Hydraulic Fracture in a Deep Gas Well (includes associated papers 26302 and 26946). SPE Prod & Fac 8 (3): 150–158. SPE-22876-PA. https://doi.org/10.2118/22876-PA.
Warpinski, N. R., Branagan, P. T., Engler, B. P. et al. 2002. Evaluation of a Downhole Tiltmeter Array for Monitoring Hydraulic Fractures. International Journal of Rock Mechanics and Mining Sciences 34 (3–4): 329. https://doi.org/10.1016/S1365-1609(97)00074-9.
Watanabe, N., Hirano, N., and Tsuchiya, N. 2008. Determination of Aperture Structure and Fluid Flow in a Rock Fracture by High-Resolution Numerical Modeling on the Basis of a Flow-Through Experiment Under Confining Pressure. Water Res. 44: W06412. https://doi.org/10.1029/2006WR005411.
Wells, O. L. and Davatzes, N. C. 2015. The History of Dilation Across Natural Fractures Due to Evolving Surface Roughness. In Proc., 40th Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, California, USA, 26–28 January. SGP-TR-204.
Willis-Richards, J., Watanabe, K., and Takahashi, H. 1996. Progress Toward a Stochastic Rock Mechanics Model of Engineered Geothermal Systems. Journal of Geophysical Research 101 (B8): 17481–17496. https://doi.org/10.1029/96JB00882.
Witherspoon P. A. 2004. Development of Underground Research Laboratories for Radioactive Waste Isolation. In Proc., Second International Symposium on Dynamics of Fluids in Fractured Rock, pp. 3–7.
Zou, Y., Ma, X., Zhang, S. et al. 2015. The Origins of Low-Fracture Conductivity in Soft Shale Formations: An Experimental Study. Energy Technology 3 (12): 1233–1242. https://doi.org/10.1002/ente.201500188.
Zhang, Y., Pan, L., Pruess, K. et al. 2011. A Time-Convolution Approach for Modeling Heat Exchange Between a Wellbore and Surrounding Formation. Geothermics 40 (4): 261–266. https://doi.org/10.1016/j.geothermics.2011.08.003.