Using Drillstem and Production Tests To Model Reservoir Relative Permeabilities
- John D. Matthews (Imperial College) | Jonathan N. Carter (Imperial College) | Robert W. Zimmerman (Imperial College)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- December 2008
- Document Type
- Journal Paper
- 1,082 - 1,088
- 2008. Society of Petroleum Engineers
- 5.6.9 Production Forecasting, 4.3.4 Scale, 5.3.4 Reduction of Residual Oil Saturation, 5.5 Reservoir Simulation, 7.5.3 Professional Registration/Cetification, 6.1.5 Human Resources, Competence and Training, 5.6.4 Drillstem/Well Testing, 2.2.2 Perforating, 3.3 Well & Reservoir Surveillance and Monitoring, 1.6.9 Coring, Fishing, 5.2.1 Phase Behavior and PVT Measurements, 5.1.1 Exploration, Development, Structural Geology, 2 Well Completion, 1.2.3 Rock properties, 5.5.8 History Matching
- 4 in the last 30 days
- 606 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 12.00|
|SPE Non-Member Price:||USD 35.00|
Relative permeabilities are fundamental to any assessment of reserves and reservoir management. When measurements on core samples are available, however, they often predict initial water production that is not experienced by individual wells. For example, dry oil production occurs from portions of reservoirs where the local water saturation is relatively high, even though the relative permeability data would predict a water cut in the range of 30 to 60%. This lack of agreement means that effective reservoir management is hampered because it is difficult for simulation models to mimic the observed reservoir production without use of data that may bear little resemblance to measurements.
After a brief discussion of relative permeability, the focus of this paper is first to examine the uncertainties in the data that are used for the predictions. This then provides a numerically structured approach to adjustments that need to be made to data so that history matching of simulation models can be achieved. The relative permeabilities, rather than saturations and fluid properties, are shown to be the least certain of the relevant data.
The second focus in the paper is to explore the reasons why the relative permeability data are so uncertain. The evidence points to the fact that oil emplacement and the subsequent geological history of the reservoirs have not been considered sufficiently in preparing core samples before making measurements. Greater reliance on drillstem and early production tests is, therefore, crucial for deriving reservoir relative permeabilities until laboratories are able to mimic oil emplacement within rock samples as experienced in the reservoir.
The main source of data is the abandoned UK North Sea reservoir Maureen (Block 16/29a). Inevitably, during the 36 years since discovery, some data have been misplaced. Nevertheless, sufficient data exist to highlight the potential need for a paradigm shift in understanding how relative permeabilities should be obtained for reservoir simulation.
There are many examples of dry oil production from portions of reservoirs where the local water saturation is relatively high (Matthews 2004). On the occasions when relative permeability data are available, predictions of the expected water cut are not zero but typically in the range of 30 to 60%. A particular example is that of the abandoned UK North Sea reservoir Maureen (Cutts 1991). This lack of agreement means that effective reservoir management is hampered because it is difficult for simulation models to mimic the observed early reservoir production without use of data that may bear little resemblance to measurements.
The focus of this paper is first to examine the uncertainties in the data that are used for the predictions. The Maureen reservoir--its data were placed in the public domain for research and training purposes by Phillips after it was abandoned (Gringarten et al. 2000)--provides the main source of information. The data examined are viscosity, saturation, and relative permeability.
Having established which data are the most uncertain, the paper then includes a brief discussion of the transition zone and oil emplacement to understand the nature of the uncertainties in relative permeability measurements and, in particular, measurements of the irreducible water saturation. From this, a new avenue of research related to oil emplacement can be identified that, if pursued, may lead ultimately to better reservoir-management models.
|File Size||1 MB||Number of Pages||7|
Beggs, H.D. 1987. Oil System Correlations. In Petroleum EngineeringHandbook, ed. H.B. Bradley, Chap. 22. Richardson, Texas: SPE.
Coats, K.H., Dempsey, J.R., and Henderson, J.H. 1971. The Use of Vertical Equilibrium inTwo-dimensional Simulation of Three-dimensional Reservoir Performance.SPEJ 11 (1): 63-71; Trans., AIME, 251. SPE-2797-PA.DOI: 10.2118/2797-PA.
Collins, A.G. 1987. Properties of Produced Waters. In PetroleumEngineering Handbook, ed. H.B. Bradley, Chap. 24. Richardson, Texas:SPE.
Cutts, P.L. 1991. The Maureen Field, Block 16/29a, UK North Sea. InUnited Kingdom Oil and Gas Fields 25 Year Commemorative/No: 265, ed.I.L. Abbott, 347. Bath, UK: Geological Society Memoirs No. 14, GeologicalSociety Publishing House.
Dawe, R.A. ed. 2000. Modern Petroleum Technology, Vol. 1 Upstream,sixth edition. London: Institute of Petroleum.
De'ath, N.G. and Schuyleman, S.F. 1981. The Geology of the Magnus Oilfield.In Petroleum Geology of Continental Shelf of North West Europe, ed. L.V.Illing and G.D. Hobson, 342. London: Institute of Petroleum.
Efnik, M.S., Hafez, H., Haajizadeh, M., Hamawi, M., Al-Mansorei, M., Kenawy,M., and Abdulla, F. 2006. Producing Dry Oil From a TransitionZone: Should This Be Called a Wedge Zone? Paper SPE 101471 presented at theAbu Dhabi Petroleum Exhibition and Conference, Abu Dhabi, UAE, 5-8 November.DOI: 10.2118/101471-MS.
Gringarten, A.C., Bond, D.J., Jackson, M.D., Jing, X.-D., Ala, M., andJohnson, H.D. 2000. A PetroleumEngineering Educational Model Based on the Maureen Field UKCS. Paper SPE64311 presented at the SPE Annual Technical Conference and Exhibition, Dallas,1-4 October. DOI: 10.2118/64311-MS.
Heaviside, J., Brown. C.E., and Gamble, I.J.A. 1987. Relative Permeability forIntermediate Wettability Reservoirs. Paper SPE 16968 presented at the SPEAnnual Technical Conference and Exhibition, Dallas, 27-30 September. DOI:10.2118/16968-MS.
Honarpour, M., Koederitz, L.F., and Harvey, A.H. 1986. RelativePermeability in Reservoirs. Boca Raton, Florida: CRC Press.
Jackson, M.D., Valvatne, P.H., and Blunt, M.J. 2005. Prediction of Wettability VariationWithin an Oil/Water Transition Zone and its Impact on Production.SPEJ 10 (2): 185-195. SPE-77543-PA. DOI: 10.2118/77543-PA.
Johnson, A. 1987. Permeability Averaged Capillary Pressure--A Supplement toLog Analysis in Field Studies. Paper EE presented at the SPWLA Annual LoggingSymposium, London, 29 June-2 July.
Kleppe, J., Delaplace, P., Lenormand, R., Hamon, G., and Chaput, E. 1997. Representation of Capillary PressureHysteresis in Reservoir Simulation. Paper SPE 38899 presented at the SPEAnnual Technical Conference and Exhibition, San Antonio, Texas, 5-8 October.DOI: 10.2118/38899-MS.
Land, C.S. 1968. Calculation ofImbibition Relative Permeability for Two- and Three-Phase Flow From RockProperties. SPEJ 8 (2): 149-156; Trans., AIME,243. SPE-1942-PA. DOI: 10.2118/1942-PA.
Matthews, J.D. 2004. Geological and physical assessment of the oil reservoirtransition zone. PhD thesis, Imperial College, London.
Matthews, J.D., Carter, J.N., and Zimmerman, R.W. (In press). Assessing thetotal uncertainty on oil saturation from electric logging.Petrophysics.
Muskat, M. 1949. Physical Principles of Oil Production. Columbus,Ohio: McGraw-Hill (repr. Springer, 1981).
Osborne, D. 1986. A World Awash with Oil. Management Today(Nov/Dec).
Rose, W.R. 1987. Relative Permeability. In Petroleum EngineeringHandbook, ed. H.B. Bradley, Chap. 28. Richardson, Texas: SPE.
Stephen, K.D., Yang, C., Carter, J., Howell, J.A., Manzocchi, T., andSkorstad, A. 2008. Upscaling uncertainty analysis in a shallow-marineenvironment. Petroleum Geoscience 14 (1): 71-84.
Straub, R. 2003. Hindsight well test analysis through appraisal anddevelopment of a north sea field: Implications for improved test design,interpretation, and history matching. PhD thesis, Heriot-Watt University,Edinburgh, Scotland.
Wilson, H.H. 2005. A review ofgeological data that conflict with the paradigm of catagenic generation andmigration of oil. J. of Petroleum Geology 28 (3): 288-300.DOI:10.1111/j.1747-5457.2005.tb00084.x.
Woodhouse, R. 1987. Problems in Sw calibration using cores and electricalmeasurements. The Log Analyst (May-June): 289.