Use of Dynamic Data and a New Material-Balance Equation for Estimating Average Reservoir Pressure, Original Gas in Place, and Optimal Well Spacing in Shale Gas Reservoirs
- Daniel Orozco (University of Calgary) | Roberto Aguilera (University of Calgary)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- November 2018
- Document Type
- Journal Paper
- 1,035 - 1,044
- 2018.Society of Petroleum Engineers
- Shale Gas Reservoirs, Average Reservoir Pressure, Flowing Data, Material Balance, Original Gas in Place
- 5 in the last 30 days
- 147 since 2007
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The average reservoir pressure is a key parameter in material-balance calculations, but its determination is challenging when dealing with shales because of their low and ultralow permeabilities. This paper presents an easy-to-reproduce methodology for calculating the average reservoir pressure from flowing data, and its use in a new material-balance equation (MBE) that considers the simultaneous contribution of free, adsorbed, and dissolved gas.
The procedure developed in this paper uses a modified gas-compressibility factor (Z') introduced in the new MBE. Because Z' accounts for the combined effect of free, adsorbed, and dissolved gas, then total original gas in place (OGIP) can be determined from extrapolation of the MBE straight line to an average reservoir pressure equal to zero. Drainage area can be estimated on the basis of calculated OGIP and volumetric equations. As such, the methodology offers the potential to help improve well spacing in shale gas reservoirs in such a way that no stranded gas is left in the reservoir, or that excess wells are not drilled in the field. This can help to improve recoveries from shales by assisting in the determination of the optimal number of wells needed to drain a given play efficiently.
In conventional reservoirs, a well is shut in, and the average reservoir pressure is determined from the corresponding pressure-buildup test. But, for the case of unconventional shale gas reservoirs, shutting the wells in is unacceptable because of the long time it would require for estimating average reservoir pressure. The methodology developed in this paper for shale gas reservoirs circumvents this problem by using dynamic data.
Production data from multistage hydraulically fractured horizontal wells completed in a Canadian shale gas reservoir are used for testing the effectiveness of the new methodology. Comparison of typical well-spacing values vs. the drainage area calculated with the new methodology leads to the conclusion that, probably, only 40% of the gas is being drained efficiently. The novelty of this work relies on the development of a methodology for calculating average reservoir pressure, OGIP, drainage area, and optimal well spacing in shale reservoirs through the combination of dynamic data and a new MBE that considers simultaneously the effects of free, adsorbed, and dissolved gas.
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Aguilera, R. 1995. Naturally Fractured Reservoirs, second edition. Tulsa, PennWell Books.
Aguilera, R. 2008. Effect of Fracture Compressibility on Gas-in-Place Calculations of Stress-Sensitive Naturally Fractured Reservoirs. SPE Res Eval & Eng 11 (2): 307–310. SPE-100451-PA. https://doi.org/10.2118/100451-PA.
Aguilera, R. 2010. Flow Units: From Conventional to Tight Gas to Shale Gas Reservoirs. Presented at the Trinidad and Tobago Energy Resources Conference, Port Spain, Trinidad, 27–30 June. SPE-132845-MS. https://doi.org/10.2118/132845-MS.
Al-Hussainy, R., Ramey Jr., H. J., and Crawford, P. B., 1966. The Flow of Real Gases Through Porous Media. J Pet Technol 18 (5): 624–636. SPE-1243-A-PA. https://doi.org/10.2118/1243-A-PA.
Cabrapán, J. C., Caliz, E. A., and Ciancaglini, M. 2014. Material Balance Analysis of Naturally or Artificially Fractured Shale Gas Reservoirs to Maximize Final Recovery. Presented at the SPE Latin American and Caribbean Petroleum Engineering Conference, Maracaibo, Venezuela, 21–23 May. SPE-169480-MS. https://doi.org/10.2118/169480-MS.
Heller, R. and Zoback, M. 2014. Adsorption of Methane and Carbon Dioxide on Gas Shale and Pure Mineral Samples. Journal of Unconventional Oil and Gas Resources 8: 14–24. https://doi.org/10.1016/j.juogr.2014.06.001.
Javadpour, F. 2009. Nanopores and Apparent Permeability of Gas Flow in Mudrocks (Shales and Siltstone). J Can Pet Technol 48 (8): 16–21. PETSOC-09-08-16. https://doi.org/10.2118/09-08-16.
Kam, P., Nadeem, M., Novlesky, A. et al. 2015. Reservoir Characterization and History Matching of the Horn River Shale: An Integrated Geoscience and Reservoir Simulation Approach. J Can Pet Technol 54 (6): 475–488. SPE-171611-PA. https://doi.org/10.2118/171611-PA.
Lopez, B. and Aguilera, R. 2013. Evaluation of Quintuple Porosity in Shale Petroleum Reservoirs. Presented at the SPE Eastern Regional Meeting, Pittsburgh, Pennsylvania, USA, 20–22 August. SPE-165681-MS. https://doi.org/10.2118/165681-MS.
Lopez, B. and Aguilera, R. 2014. Petrophysical Quantification of Multiple Porosities in Shale Petroleum Reservoirs. Presented at the SPE/CSUR Unconventional Resources Conference–Canada, Calgary, 30 September–2 October. SPE-171638-MS. https://doi.org/10.2118/171638-MS.
Mattar, L. and McNeil, R. 1998. The “Flowing” Gas Material Balance. J Can Pet Technol 37 (2): 52–55. PETSOC-98-02-06. https://doi.org/10.2118/98-02-06.
Mattar, L. and Anderson, D. 2005. Dynamic Material Balance (Oil or Gas-in-Place Without Shut-Ins). Presented at the Canadian International Petroleum Conference, Calgary, 7–9 June. PETSOC 2005-113.
Orozco, D. and Aguilera, R. 2015. A Material Balance Equation for Stress-Sensitive Shale Gas Reservoirs Considering the Contribution of Free, Adsorbed, and Dissolved Gas. Presented at the SPE/CSUR Unconventional Resources Conference, Calgary, 20–22 October. SPE-175964-MS. https://doi.org/10.2118/175964-MS.
Quirein, J., Witkowsky, J., Truax, J. A. et al. 2010. Integrating Core Data and Wireline Geochemical Data for Formation Evaluation and Characterization of Shale-Gas Reservoirs. Presented at the SPE Annual Technical Conference and Exhibition, Florence, Italy, 19–22 September. SPE-134559-MS. https://doi.org/10.2118/134559-MS.
Swami, V., Settari, A. (Tony), and Javadpour, F. 2013. A Numerical Model for Multi-Mechanism Flow in Shale Gas Reservoirs With Application to Laboratory Scale Testing. Presented at the EAGE Annual Technical Conference & Exhibition incorporating SPE Europec, London, 10–13 June. SPE-164840-MS. https://doi.org/10.2118/164840-MS.
Wu, P. and Aguilera, R. 2012. Investigation of Gas Shales at Nanoscale Using Scan Electron Microscopy, Transmission Electron Microscopy, and Atomic Force Microscopy. Presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, 8–10 October. SPE-159887-MS. https://doi.org/10.2118/159887-MS.