Geomechanical Well Testing: A New Methodology for Interpretation of Pressure Transient Testing Data for Geomechanical Applications
- Saeed Rafieepour (The University of Tulsa) | Silvio Baldino (The University of Tulsa) | Stefan Miska (The University of Tulsa) | Evren Ozbayoglu (The University of Tulsa) | Jianguo Zhang (BP America Inc.)
- Document ID
- Society of Petroleum Engineers
- SPE Annual Technical Conference and Exhibition, 26-29 October, Virtual
- Publication Date
- Document Type
- Conference Paper
- 2020. Society of Petroleum Engineers
- 5.6.4 Drillstem/Well Testing, 5.6.3 Pressure Transient Testing, 0.2 Wellbore Design, 0.2.2 Geomechanics, 3 Production and Well Operations, 5.6 Formation Evaluation & Management, 5 Reservoir Desciption & Dynamics, 5.6.1 Open hole/cased hole log analysis
- Well testing, Geomechanical, Poroelastoplastic, Poroelastic, Numerical modeling
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Rock mechanics triaxial tests and well logs are the main source for determination of mechanical properties of reservoir. These methods obtain values for mechanical properties corresponding to parts of the formation close to the well area. The experimental approach is much more limited as the coring operation is costly and is performed in a handful of appraisal/exploratory wells. Here, a novel methodology, geomechanical well testing, is presented to estimate the elastic and plastic mechanical properties using pressure transient testing. In the first part of the paper, the theory of poroelasticity was utilized to develop a geomechanical well testing technique, which attains estimation of reservoir's poroelastic properties. The technique is on the basis of developing a diffusivity equation incorporating mechanical deformation into the fluid transport in porous media and via applying different mechanical boundary conditions, one can obtain several closed-form solutions for storage coefficient. The developed storage coefficients, however, include Poisson's ratio (PR) as the target variable to estimate from conventional well testing. As a verification, a case study was conducted using the pressure transient data from a sandstone aquifer. Adopting the conventional well testing principles, three different values for PR were obtained. The first impression to this point was to decide which value is the most representing value for the aquifer under investigation. We envisioned two methods for this critical step: 1) comparison of obtained PR values from the geomechanical well testing technique with the one estimated via another reliable source such as well log/seismic and/or 2) comparison of pressure-time measurements with available numerical simulations. We took this finding for granted and devise a way to obtain an estimation of dominant boundary conditions of a reservoir. Once the dominant deformational behavior was assessed, the technique may be re-implemented along with future well testing measuements to monitor the evolutions of elastic properties during the life of reservoir. The second part of the paper deals with another geomechanical well testing technique, which provides a tool for estimation of strength properies through developing a generalized diffusivity equation using poroplasticity theory with a plastic potential function based on Mohr-Coulomb yield/failure criterion. An analytical solution was obtained under uniaxial strain assumption, which can be used to estimate internal friction angle or dilation angle.
|File Size||1 MB||Number of Pages||13|
Baldino, S., Rafieepour, S. and Miska, S.Z., 2017. In-Situ Poisson's Ratio Determination under Different Deformational Conditions. In SPE Oklahoma City Oil and Gas Symposium, 27–31 March, Oklahoma City, Oklahoma, USA. https://doi.org/10.2118/185112-MS.
Rafieepour, S., Baldino, S., Miska, S.Z., 2020. Determination of in-situ elastic properties and reservoir boundary conditions. Journal of Natural Gas Science and Engineering. https://doi.org/10.1016/j.jngse.2020.103397.
Rafieepour, S., Miska, S.Z., Ozbayoglu, E., Yu, M., Takach, N.E., Zhang, J. and Majidi, R., 2017. Experimental study of reservoir stress path and hysteresis during depletion and injection under different deformational conditions. In 51st US Rock Mechanics/Geomechanics Symposium. American Rock Mechanics Association.