Gravity changes measured at the seafloor are sensitive to fluid redistribution in hydrocarbon reservoirs. As an example, vertical movements of water-gas contacts smaller than a meter can be detected under some circumstances. Seafloor subsidence monitoring uses water pressure measurements at the seafloor as a starting point. Once the required tide corrections are applied, the method reaches accuracies as low as 2 mm, depending on the field conditions. Subsidence is a required correction for the interpretation of gravity results, and it is by itself a valuable monitoring tool, sensitive to important reservoir and overburden properties. It is directly related to pressure depletion and lateral compartmentalization, and in some cases, it is a key factor for the safety of the installations. In this abstract, we review the principles of the 4D gravity and subsidence monitoring technology. We then discuss some field cases from the Norwegian Continental Shelf that illustrate the value that this type of data provides for reservoir management. Finally, we discuss what are the drivers of the cost of the technology and what steps are taken by the industry to reduce cost, and hence to make it feasible in more fields.


Article metrics loading...

Loading full text...

Full text loading...


  1. Alnes, H.
    , et al., 2010, Experiences on Seafloor Gravimetric and Subsidence Monitoring Above Producing Reservoirs: 72nd Conference and Exhibition, EAGE, Extended Abstracts, L010.
    [Google Scholar]
  2. Pettersen, Ø. and Kristiansen, T.G.
    , 2009, Improved compaction modeling in reservoir simulation and coupled rock mechanics/flow simulation, with examples from the Valhall field, SPE Reservoir Evaluation& engineering (SPE 113003).
  3. Ruiz, H. et al.
    , 2015, Monitoring of Offshore Reservoirs Using 4D Gravimetry at the Seafloor - State of the Art: 77th Conference and Exhibition, EAGE, Extended Abstracts, Tu N101 08.
    [Google Scholar]
  4. Ruiz, H., et al.
    , 2016a, Monitoring offshore reservoirs using 4D gravity and subsidence with improved tide corrections, SEG Annual Meeting, October 2016, SEG-2016-13576781.
    [Google Scholar]
  5. Ruiz, H. et al.
    , 2016b, A New Method for Field-wide Real-time Subsidence Monitoring with Subcentimeter Accuracy, 78th Conference and Exhibition, Extended Abstracts, Tu LHR2 04.
    [Google Scholar]
  6. Røste, T. and Ke, G.
    , “Overburden 4D time shifts — Indicating undrained areas and fault transmissibility in the reservoir”, The Leading Edge, May2017.
    [Google Scholar]
  7. Van den Beukel, A. et al.
    , 2014, Integrated Reservoir Monitoring of the Ormen Lange field: Time lapse seismic, Time lapse gravity and seafloor deformation monitoring: The Biennial Geophysical Seminar 2014, NPF, Extended Abstracts.
    [Google Scholar]
  8. StatoilASA., UelandI.
    , 2015, Modnet frem brønn på utradisjonelt vis. ORIGO, 40–41.
    [Google Scholar]
  9. Rocca, F. et al.
    , 2013, Advanced Insar interferometry for reservoir monitoring. First break, volume 31, May, 2013.
    [Google Scholar]
  10. van Opstal, G.
    , 1974, The effect of base rock rigidity on subsidence due. Proceedings of the Third Congress of the International Society of Rock Mechanics, (pp. 1–7September). Denver, Colorado, USA.
    [Google Scholar]
  11. van Thienen-Visser, K., Pruiksma, J. P., and Breunese, J. N.
    , 2015, Compaction and subsidence of the Groningen gas field. Proc. IAHS, 372, (pp. 367–373).
    [Google Scholar]
  12. Vatshelle, M., et al.
    , 2017, Monitoring the Ormen Lange field with 4D gravity and seafloor subsidence, 79th EAGE Conference & Exhibition, Extended Abstracts, Th A1 06.
    [Google Scholar]
  13. VevatneJ., et al.
    , 2012, Use of field-wide seafloor time-lapse gravity in history matching the Mikkel gas condensate field, 74th EAGE Conference & Exhibition, Extended Abstracts, F040.
    [Google Scholar]

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error