Advanced Semianalytical Geomechanical Model for Wellbore-Strengthening Applications
- Mojtaba P. Shahri (Weatherford) | Trevor T. Oar (Weatherford) | Reza Safari (Weatherford) | Moji Karimi (Weatherford) | Uno Mutlu (Weatherford)
- Document ID
- Society of Petroleum Engineers
- SPE Journal
- Publication Date
- December 2015
- Document Type
- Journal Paper
- 1,276 - 1,286
- 2015.Society of Petroleum Engineers
- wellbore strengthening, fracture width distribution, casing while drilling, particle size distribution, lost circulation material
- 3 in the last 30 days
- 811 since 2007
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Drilling depleted reservoirs often encounters a host of problems leading to increases in cost and nonproductive time. One of these problems faced by drillers is lost circulation of drilling fluids, which can lead to greater issues such as differential sticking and well-control events. Field applications show that wellbore strengthening effectively helps reduce mud-loss volume by increasing the safe mud-weight window. Wellbore-strengthening applications are usually designed on the basis of induced-fracture characteristics (i.e., fracture length, fracture width, and stress-intensity factor). In general, these fracture characteristics depend on several parameters, including in-situ stress magnitude, in-situ stress anisotropy, mechanical properties, rock texture, wellbore geometry, mud weight, wellbore trajectory, pore pressure, natural fractures, and formation anisotropy. Analytical models available in literature oversimplify the fracture-initiation and fracture-propagation process with assumptions such as isotropic stress field, no near-wellbore stress-perturbation effects, vertical or horizontal wells only (no deviation/inclinations), constant fracture length, and constant pressure within the fracture. For more-accurate predictions, different numerical methods, such as finite element and boundary element, have been used to determine fracture-width distribution. However, these calculations can be computationally costly or difficult to implement in near-real time. The aim of this study is to provide a fast-running, semianalytical work flow to accurately predict fracture-width distribution and fracture-reinitiation pressure (FRIP). The algorithm and work flow can account for near-wellbore-stress perturbations, far-field stress anisotropy, and wellbore inclination/deviation. The semianalytical algorithm is modeled after singular integral formulations of stress field and solved by use of Gauss-Cheyshev polynomials. The proposed model is computationally efficient and accurate. The model also provides a comprehensive perspective on formation-strengthening scenarios; a tool for improved lost-circulation-materials design; and an explanation of how they are applicable during drilling operation (in particular, through depleted zones). Sensitivity analysis included in this paper quantifies the effect of different rock properties, in-situ-stress field/anisotropy, and wellbore geometry/deviation on the fracture-width distribution and FRIP. In addition, the case study presented in this paper demonstrates the applicability of the proposed work flow in the field.
|File Size||2 MB||Number of Pages||11|
Alberty, M. W. and McLean, M. R. 2004. A Physical Model for Stress Cages. Presented at SPE Annual Technical Conference and Exhibition, Houston, Texas, 26–29 September. SPE-90493-MS. http://dx.doi.org/10.2118/90493-MS.
Aadnoy, B.S. and Looyeh, R. 2010. Petroleum Rock Mechanics: Drilling Operation and Well Design. Oxford, UK: Gulf Professional Publishing
Carbonell, R. S. and Detournay, E. 1995. Modeling Fracture Initiation and Propagation from a Pressurized Hole: A Dislocation Based Approach. Presented at the 35th US Symposium on Rock Mechanics, Reno, Nevada, 5–7 June. ARMA-95-0465.
Dupriest, F. E. 2005. Fracture Closure Stress (FCS) and Lost Returns Practices. Presented at the SPE/IADC Drilling Conference, Amsterdam, The Netherlands, 23–25 February. SPE-92192-MS. http://dx.doi.org/10.2118/92192-MS.
Erdogan, F., and Gupta, G. D. 1972. On the Numerical Solution of Singular Integral Equations. Q. Appl. Math. 29: 525–534.
Guo, Q., Feng, Y. Z. and Jin, Z. H. 2011. Fracture Aperture for Wellbore Strengthening Applications. Presented at the 45th US Rock Mechanics/Geomechanics Symposium, San Francisco, California, 26–29 June. ARMA-11-378.
Morita, N. and Fuh, G. F. 2012. Parametric Analysis of Wellbore-Strengthening Methods from Basic Rock Mechanics. SPE Drill & Compl 27 (2): 315–327. SPE-145765-PA. http://dx.doi.org/10.2118/145765-PA.
Muskhelishvili, N.I. 1953. Some Basic Problems of the Mathematical Theory of Elasticity, third edition, trans. J.R.M. Radok. Groningen, The Netherlands: P. Noordhoff Ltd.
Newman, J. C. Jr. 1971. An Improved Method of Collocation for the Stress Analysis of Cracked Plates with Various Shaped Boundaries. NASA Technical Note, TN-D6376, National Aeronautics and Space Administration, Washington, DC, August 1971.
Peška, P., and Zoback, M. D. 1995. Compressive and Tensile Failure of Inclined Well Bores and Determination of In Situ Stress and Rock Strength. J. Geophys. Res.-Sol. Ea. 100 (B7): 12791–12811. http://dx.doi.org/10.1029/95JB00319.
Rubinstein, A. A. 1987. Response: Discussion of “Analysis of a Crack Emanating from a Circular Hole in a Loaded Plane” by W.E. Warren. Int. J. Fracture 35 (4): R77–R78. http://dx.doi.org/10.1007/BF00276363.
Rubinstein, A. A. and Sadegh, A. M. 1986. Analysis of a Crack Emanating From a Circular Hole in a Loaded Plane. Int. J. Fracture 32 (1): 47–57. http://dx.doi.org/10.1007/BF00045892.
Shahri, M. P., Miska, S. Z., Yu, M., et al. 2013. Effect of Pore Pressure Changes on Formation Fracture Pressure in Non-hydrostatic Stress Field. Presented at the 47th US Rock Mechanics/Geomechanics Symposium, San Francisco, California, 23–26 June. ARMA-2013-125.
van Oort, E., Friedheim, J., Pierce, T., et al. 2011. Avoiding Losses in Depleted and Weak Zones by Constantly Strengthening Wellbores. SPE Drill & Compl 26 (4): 519–530. SPE-125093-PA. http://dx.doi.org/10.2118/125093-PA.
Wang, H., Towler, B. and Soliman, M. 2007. Fractured Wellbore Stress Analysis: Sealing Cracks to Strengthen a Wellbore. Presented at the SPE/IADC Drilling Conference, Amsterdam, The Netherlands, 20–22 February. SPE-104947-MS. http://dx.doi.org/10.2118/104947-MS.
Wang, H., Soliman, M. and Towler, B. 2009. Investigation of Factors for Strengthening a Wellbore by Propping Fractures. SPE Drill & Compl 24 (3): 441–451. SPE-112629-PA. http://dx.doi.org/10.2118/112629-PA.
Warren, W. E., 1982. The Quasi-static Stress Field Around a Fractured Wellbore. Int. J. Fracture 18 (2): 113–124. http://dx.doi.org/10.1007/BF00019636.
Warren, W. E. 1987. Discussion: “Analysis of a Crack Emanating From a Circular Hole in a Loaded Plane,” by A. A. Rubenstein and A. M. Sedegh. Int. J. Fracture 35 (4): R75–R76. http://dx.doi.org/10.1007/BF00276362.
Whitfill, D. 2008. Lost Circulation Material Selection, Particle Size Distribution and Fracture Modeling with Fracture Simulation Software. Presented at the IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition, Jakarta, 25–27 August. SPE-115039-MS. http://dx.doi.org/10.2118/115039-MS.