An Early-Time Model for Drawdown Testing of a Hydrate-Capped Gas Reservoir
- Shahab Gerami (National Iranian Oil Co.) | Mehran Pooladi-Darvish (Fekete Associates Inc.)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- August 2009
- Document Type
- Journal Paper
- 595 - 609
- 2009. Society of Petroleum Engineers
- 1 in the last 30 days
- 814 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 12.00|
|SPE Non-Member Price:||USD 35.00|
Development of natural gas hydrates as an energy resource has gained significant interest during the past decade. Hydrate reservoirs may be found in different geologic settings including deep ocean sediments and arctic areas. Some reservoirs include a free-gas zone beneath the hydrate and such a situation is referred to as a hydrate-capped gas reservoir. Gas production from such a reservoir could result in pressure reduction in the hydrate cap and endothermic decomposition of hydrates.
Well testing in conventional reservoirs is used for estimation of reservoir and near-wellbore properties. Drawdown testing in a hydrate-capped gas reservoir needs to account for the effect of gas from decomposing hydrates. This paper presents a 2D (r,z) mathematical model for a constant-rate drawdown test performed in a well completed in the free-gas zone of a hydrate-capped gas reservoir during the earlytime production. Using energy and material balance equations, the effect of endothermic hydrate decomposition appears as an increased compressibility in the resulting governing equation. The solution for the dimensionless wellbore pressure is derived using Laplace and finite Fourier cosine transforms. The solution to the analytical model was compared with a numerical hydrate reservoir simulator across some range of hydrate reservoir parameters.
The use of this solution for determination of reservoir properties is demonstrated using a synthetic example. Furthermore, the solution may be used to quantify the contribution of hydrate decomposition on production performance.
In recent years, demands for energy have stimulated the development of unconventional gas resources, which are available in enormous quantities around the world. Gas hydrate as an unconventional gas resource may be found in two geologic settings (Sloan 1991): (1) on land in permafrost regions, and (2) in the ocean sediments of continental margins. During the last decade, extensive efforts consisting of detection of the hydrate-bearing areas, drilling, logging, coring of the intervals, production pilot-testing, and mathematical modeling of hydrate reservoirs have been pursued to evaluate the potential of gas production from these gas-hydrate resources.
|File Size||1 MB||Number of Pages||15|
Agarwal, R.G., Gardner, D.C., Kleinsteiber, S.W., and Fussell, D.D. 1999. Analyzing Well Production Data UsingCombined-Type-Curve and Decline-Curve Analysis Concepts. SPE Res Eval& Eng 2 (5): 478-486. SPE-57916-PA. doi:10.2118/57916-PA.
Al-Hussainy, R., Ramey, H.J. Jr., and Crawford, P.B. 1966. The Flow of RealGases Through Porous Media. J. Pet Tech 18 (May):624-636.
Brons, F. and Marting, V.E. 1961. The Effect of Restricted Fluid Entry onWell Productivity. J. Pet Tech 13 (2): 172-174;Trans., AIME, 222. SPE-1322-G. doi: 10.2118/1322-G.
Fraim, M.L. and Wattenbarger, R.A. 1987. Gas Reservoir Decline-Curve AnalysisUsing Type Curves With Real Gas Pseudopressure and Normalized Time. SPEForm Eval 2 (4): 671-682. SPE-14238-PA. doi:10.2118/14238-PA.
Gerami, S. 2007. Predictive and production analysis models for theunconventional gas reservoirs. PhD thesis, University of Calgary, Calgary,Alberta.
Gerami, S. and Pooladi-Darvish, M. 2006. Material Balance andBoundary-Dominated Flow Models for Hydrate-Capped Gas Reservoirs. Paper SPE102234 presented at the SPE Annual Technical Conference and Exhibition, SanAntonio, Texas, USA, 24-27 September. doi: 10.2118/102234-MS.
Gerami, S. and Pooladi-Darvish, M. 2007a. Effect of Hydrates on SustainingReservoir Pressure in a Hydrate-Capped Gas Reservoir. J. Can. Pet. Tech.46 (10): 39-48.
Gerami, S. and Pooladi-Darvish, M. 2007b. Predicting gas generationby depressurization of hydrates where the sharp-interface assumption is notvalid. J. of Petroleum Science and Engineering 56(1-3): 146-164. doi:10.1016/j.petrol.2006.01.012.
Goel, N., Wiggins, M., and Shah, S. 2001. Analytical modeling ofgas recovery from in situ hydrates dissociation. J. of Petroleum Scienceand Engineering 29 (2): 115-127.doi:10.1016/S0920-4105(01)00094-8.
Hong, H. 2003. Modeling of Gas Production from Hydrates in Porous Media. MScthesis, University of Calgary, Calgary, Alberta.
Hong, H. and Pooladi-Darvish, M. 2005. Simulation of depressurization forgas production from gas hydrate reservoirs. J. Can. Pet. Tech.44 (11): 39-46.
Hong, H., Pooladi-Darvish, M., and Bishnoi, P.R. 2003. Analytical Modelingof Gas Production from Hydrates in Porous Media. J. Can. Pet. Tech.42 (11): 45-56.
Ji, C., Ahmadi, G., and Smith, D.H. 2001. Natural gas productionfrom hydrate decomposition by depressurization. Chemical EngineeringScience 56 (20): 5801-5814.doi:10.1016/S0009-2509(01)00265-2.
Kamath, V.A. and Holder, G.D. 1987. Dissociation heat transfercharacteristics of methane hydrates. AIChE J. 33 (2):347-350. doi:10.1002/aic.690330228.
Kim, H.C., Bishnoi, P.R., Heidemann, R.A., and Rizvi, S.S.H. 1987. Kinetics of methanehydrate decomposition. Chemical Engineering Science 42(7): 1645-1653. doi:10.1016/0009-2509(87)80169-0.
Lee, W.J. and Holditch, S.A. 1982. Application of Pseudotime to BuildupTest Analysis of Low-Permeability Gas Wells With Long-Duration Wellbore StorageDistortion. J. Pet Tech 34 (12): 2877-2888.SPE-9888-PA. doi: 10.2118/9888-PA.
Makogon, Y.F. 1997. Hydrates of Hydrocarbons, 396-448. Tulsa,Oklahoma: PennWell Publishing Co.
Masuda, Y., Naganawa, S., Ando, S., and Sato, K. 1997. Numerical calculationof gas-production performance from reservoirs containing natural gas hydrates.Oral presentation SPE 38291 given at the SPE Western Regional Meeting, LongBeach, California, USA, 25-27 June.
Mattar, L. 1999. Derivative Analysis Without Type Curves. J. Can. Pet.Tech. (Special Edition) 38 (13): 1-6.
Moridis, G.J. 2002. NumericalStudies of Gas Production from Methane Hydrates. Paper SPE 75691 presentedat the SPE Gas Technology Symposium, Calgary, 30 April-2 May. doi:10.2118/75691-MS.
Muskat, M. 1946. The Flow of Homogeneous Fluid Through Porous Media,273. Ann Arbor, Michigan: J.W. Edwards.
NETL. 2007. Methane Hydrate Reservoir Simulator Code Comparison Study: AnInternational Effort to Compare Methane Hydrate Reservoir Simulators, http://www.netl.doe.gov/technologies/oil-gas/FutureSupply/MethaneHydrates/MH_CodeCompare/MH_CodeCompare.html(accessed January 2007).
Pooladi-Darvish, M. 2004. GasProduction from Hydrate Reservoirs and its Modeling. J. Pet Tech56 (6): Distinguished Author Series, 65-71. SPE-86827-MS. doi:10.2118/86827-MS.
Sabet, M.A. 1991. Well Test Analysis, Vol. 8. Houston, Texas:Contributions in Petroleum Geology and Engineering, Gulf PublishingCompany.
Saidikowski, R.M. 1979. Numerical Simulations of the CombinedEffects of Wellbore Damage and Partial Penetration. Paper SPE 8204presented at the SPE Annual Technical Conference and Exhibition, Las Vegas,Nevada, USA, 23-26 September. doi: 10.2118/8204-MS.
Selim, M.S. and Sloan, E.D. 1990. Hydrate Dissociation in Sediment.SPE Res Eng 5 (2): 245-251; Trans., AIME,289. SPE-16859-PA. doi: 10.2118/16859-PA.
Seth, M.S. 1968. Unsteady-state pressure distribution in a finite reservoirwith partial wellbore opening. J. Can. Pet. Tech. 7(October-December): 153-163.
Sloan, E.D. Jr. 1991. NaturalGas Hydrates. J. Pet Tech 43 (12): 1414-1417;Trans., AIME, 291. SPE-23562-PA. doi: 10.2118/23562-PA.
Stehfest, H. 1970. Algorithm 368: Numericalinversion of Laplace transforms. Communications of the ACM13 (1): 47-49. doi: 10.1145/361953.361969.
Streltsova-Adams, T.D. 1979. Pressure Drawdown in a Well WithLimited Flow Entry. J. Pet Tech 31 (11): 1469-1476.SPE-7486-PA. doi: 10.2118/7486-PA.
Sun, X. and Mohanty, K.K. 2006. Kinetic simulation ofmethane hydrate formation and dissociation in porous media. ChemicalEngineering Science 61 (11): 3476-3496.doi:10.1016/j.ces.2005.12.017.
Swinkels, W.J.A.M. and Drenth, R., J.J. 1999. Thermal Reservoir Simulation Model ofProduction from Naturally Occurring Gas Hydrate Accumulations. Paper SPE56550 presented at the SPE Annual Technical Conference and Exhibition, Houston,3-6 October. doi: 10.2118/56550-MS.
Tabatabaie, H. and Pooladi-Darvish, M. 2009. Material Balance Models fromHydrate Reservoirs Underlain with Free Gas. J. of Natural Gas Science andEngineering (In press).