High-Precision Relative Depth and Subsidence Mapping from Seafloor Water Pressure Measurements
- Torkjell Stenvold (Norwegian U. of Science and Technology) | Ola Eiken (Statoil ASA) | Mark Zumberge (U. of California) | Glenn Sasagawa (Scripps Inst. of Oceanography) | Scott Nooner (Scripps Inst. of Oceanography)
- Document ID
- Society of Petroleum Engineers
- SPE Journal
- Publication Date
- September 2006
- Document Type
- Journal Paper
- 380 - 389
- 2006. Society of Petroleum Engineers
- 5.4 Enhanced Recovery, 4.5.10 Remotely Operated Vehicles, 4.6 Natural Gas, 7.2.3 Decision-making Processes, 5.5 Reservoir Simulation, 5.4.2 Gas Injection Methods, 4.3.4 Scale, 2.4.3 Sand/Solids Control, 4.2 Pipelines, Flowlines and Risers, 3.3 Well & Reservoir Surveillance and Monitoring, 1.6.9 Coring, Fishing, 5.3.4 Integration of geomechanics in models
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A method to accurately measure seafloor subsidence away from platform locations is presented. The method is based on seafloor water pressure, which is measured on top of predeployed benchmarks visited one after another using a remotely operated vehicle (ROV) and is at the same time measured continuously throughout the survey at one or more reference locations. Because no significant subsidence is expected during a few days of data acquisition, high-precision relative depths representative for the average time of the survey can be obtained. Accurate subsidence estimates between seafloor surveys are found assuming negligible subsidence at benchmarks located outside the field.
Results from six seafloor surveys performed at two gas fields in the North Sea are presented. For an area of 1 km2 at 80 m water depth, single-measurement relative depth precision (standard deviation) of 0.4 cm was obtained. Correspondingly, for an area of 700 km2 at 295 to 345 m water depth, 0.6 cm was obtained. Single-station subsidence accuracy down to 1 cm is achieved from the two most recent pressure surveys at the large field. A subsidence signal is seen for this difference, and it is compared with modeled subsidence. Error budgets for depth precision and subsidence, incorporating instrumental and environmental errors, are discussed.
Reservoir compaction caused by the extraction of hydrocarbons usually results in surface subsidence. The most vulnerable fields are those with thick and soft reservoir formations being exposed to a large drop in pore pressure. For such fields, reservoir compaction can be a major energy drive for production that enhances the recovery of the field (Merle et al. 1976). Reservoir compaction can also lead to a reduction in permeability. When significant subsidence occurs, it can cause well failures and costly repairs of surface structures such as platforms and pipelines (Bruno 1992).
Subsidence monitoring can improve the safety of field installations, and it may also be used to estimate reservoir behavior and formation properties. Marchina (1996) reported examples of high-accuracy leveling data from the Groningen gas field used to estimate pressure depletion in the aquifer by solving a linear inverse problem, and Nagel (1998) used bathymetry data from the Ekofisk field to achieve estimates of overburden properties.
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Babcock, J.M., Kirkendall, B.A., and Orcutt, J.A. 1994. Relationshipsbetween ocean bottom noise and the environment. Bull. Seis. Soc. Am.84: 1991-2007.
Bruno, M.S. 1992. Subsidence-Induced Well Failure.SPEDE 7 (2): 148-152. SPE-20058-PA.
Chadwick, W.W. Jr., Nooner, S.L.,Zumberge, M.A., Embley, R.W., and Fox, C.G. 2006. Vertical deformationmonitoring at Axial Seamount since its 1998 eruption using deep-sea pressuresensors. Journal of Volcanology and Geotherm. Research 150(1-3): 300-312.
Davis, E., Wright, C., Demetrius, S., Choi, J., and Galey, G. 2000. Precise Tiltmeter SubsidenceMonitoring Enhances Reservoir Management. Paper SPE 62577 presented at theSPE/AAPG Western Regional Meeting, Long Beach, California, 19-22 June.
Eble, M.C. and Gonzalez, F.I. 1990. Deep-Ocean Bottom Pressure Measurementsin the Northeast Pacific. Tsunami Project, PMEL, NOAA Report 1196.
Egbert, G.D., Bennett, A.F., and Foreman, M.G.G. 1994. TOPEX/POSEIDON tides estimatedusing a global inverse model. J. Geophys. Res. 99 (24):821-824.
Eiken, O., Zumberge, M., Stenvold, T., Sasagawa, G., and Nooner, S. 2004.Gravimetric monitoring of gas production from the Troll field. Expandedabstracts, SEG Annual International Meeting. 2243-2246.
Gutierrex, M. and Lewis, R.W. 1998. The Role of Geomechanics in ReservoirSimulation. Paper SPE 47392 presented at the SPE/ISRM Rock Mechanics inPetroleum Engineering Conference, Trondheim, 8-10 July.
Hettema, M., Papamichos, E., and Schutjens, P. 2002. Subsidence Delay: FieldObservations and Analysis. Oil & Gas Science and Technology57 (5): 443-458.
Holt, R.M., Brignol, M., Fjaer, E., Erling, T., and Kenter, C.J. 1994. Core Damage Effects on CompactionBehavior. Paper SPE 28027 presented at the SPE/ISRM Rock Mechanics inPetroleum Engineering Conference, Delft, The Netherlands, 29-31 August.
Houston, M.H. and Paros, J.M. 1988. High Accuracy Pressure Instrumentationfor Underwater Applications. Paper presented at the IEEE Intl. Symposium onUnderwater Technology, Tokyo, 15-17 April.
Lighthill, J. 1978. Waves in Fluids. Cambridge: Cambridge U.Press.
Macini, P. and Mesini, E. 2002. Radioactive Marker TechniqueApplications To Evaluate Compaction in Environmentally Sensitive Areas.Paper SPE 74411 presented at the SPE International Petroleum Conference inMexico, Villahermosa, Mexico, 10-12 February.
Marchina, P.J.M. 1996. The Useof Subsidence Data To Monitor Reservoir Behavior. Paper SPE 36918 presentedat the SPE European Petroleum Conference, Milan, Italy, 22-24 October.
Merle, H.A, Kentie, C.J.P., van Opstal, G.H.C., and Schneider, G.M.G. 1976.The Bachaquero Study—A CompositeAnalysis of the Behavior of a Compaction Drive/Solution Gas DriveReservoir. JPT 28 (9): 1107-1115; Trans., AIME,261. SPE-5529-PA.
Mes, M.J. 1991. Accuracy ofOffshore Subsidence Measurements With Seabed Pressure Gauges. SPEFE6 (4): 463-469. SPE-19183-PA.
Mes, M.J., Landau, H., and Luttenberger, C. 1996. Ekofisk Automatic GPSSubsidence Measurements. Sea Technology 37 (10): 15-22.
Nagel, N.B. 1998. Ekofisk FieldOverburden Modelling. Paper SPE 47345 presented at the SPE/ISRM RockMechanics in Petroleum Engineering Conference, Trondheim, 8-10 July.
Nooner, S.L. 2005. Gravity changes associated with underground injection ofCO2 at the Sleipner storage reservoir in the North Sea, and other marinegeodetic studies. PhD dissertation. U. of California, San Diego.
Sasagawa, G.S., Crawford, W., Eiken, O., Nooner, S., Stenvold, T., andZumberge, M.A. 2003. A NewSeafloor Gravimeter. Geophysics 68 (2): 544-553.
Vennard, J.K. and Street, R.L.1982. Elementary Fluid Mechanics. New York City: Wiley &Sons.
Water Level Recorders WLR 7 & WLR 8. 2000. Data Sheet D 196. AanderaaInstruments, www.aanderaa.com.