1887

Abstract

Summary

Computation of maximum column height is common during evaluation of overpressured traps. The main idea behind such computations is to assume tensile fracturing, and that the hydrocarbon buoyancy cannot exceed the difference between the fracturing pressure and the reservoir pore pressure. The uncertainties of such computations are rarely addressed and have to date not been quantified.

We perform such quantification by using pre-production reservoir pore pressure variations to estimate the accuracy that can realistically be attained in evaluating pore pressures in undrilled prospects. We have also analysed uncertainties in fracture pressure determination from leak off tests. This was performed by comparing leak off pressures and fracture closing pressure for a large number of extended leak off tests from the Norwegian Continental Shelf. The uncertainties of the fracturing pressure is frequently 5 MPa or more, which is comparable to the buoyancy of a 1 km gas column. We therefore conclude that computation of maximum column heights should not be computed from individual wells, and that computations based on regional fracture pressure trends need further verification.

Loading

Article metrics loading...

/content/papers/10.3997/2214-4609.201700640
2017-06-12
2024-03-28
Loading full text...

Full text loading...

References

  1. Andrews, J., Fintland, S., Helstrup, O. A., Horsrud, P. and Raaen, A. M.
    , 2016, Use of unique database of good quality stress data to investigate theories of fracture initiation, fracture propagation and the stress state in the subsurface. Paper presented at the 50th US Rock Mechanics / Geomechanics Symposium held in Houston, Texas, USA, 26–29 June 2016, paper AMRA-16-887.
    [Google Scholar]
  2. Gaarenstroem, L., Tromp, R. A. J., de Jong, M. C. & Brandenburg, A. M.
    1993. Overpressures in the Central North Sea; implications for trap integrity and drilling safety. In: Parker, J. R. (ed.) Petroleum Geology of Northwest Europe: Proceedings of the 4th Conference. The Geological Society, London, 1305–1313.
    [Google Scholar]
  3. Grauls, D., Pascaud, F. and Rives, T.
    , 2002. Quantitative fault seal assessment in hydrocarbon-compartmentalized structures using fluid pressure data. In A. G.Koestler and R.Hunsdale (eds.), Hydrocarbon seal quantification. Norwegian Petroleum Society, Special Publication no 11, p.141–156.
    [Google Scholar]
  4. HermanrudC., Nordgârd BolâsH. M.
    , 2002, Leakage from overpressured hydrocarbon reservoirs at Haltenbanken and in the northern North Sea: In: Hydrocarbon Seal Quantification, NPF Spec. Publ. 11, p. 203–214, Elsevier, Amsterdam.
    [Google Scholar]
  5. Lothe, A., and Tommerâs, A.
    , 2007, Stochastic Monte-Carlo simulation of overpressure probability distribution in teh Halten Terrace area. AAPG search and discovery article #40230, 6p.
    [Google Scholar]
  6. Nordgârd BolâsH. M. and Hermanrud, C.
    , 2003, Hydrocarbon leakage processes and retention capacities offshore Norway. Petroleum Geoscience, v. 9, p. 321–332.
    [Google Scholar]
  7. Nordgârd Bolâs, H. M., Hermanrud, C., and Teige, G. M. G.
    , 2005, Seal capacity estimation from subsurface pore pressures. Basin Research, v. 17, p. 583–599.
    [Google Scholar]
  8. Nordgârd Bolâs, H. M.
    , 2008, Sealing mechanisms and hydrocarbon trap integrity in overpressured sedimentary basins. Dr. Philos thesis, University of Bergen, Norway.
    [Google Scholar]
  9. Teige, G. M. G., Hammervold Thomas, W., Hermanrud, C., Oren, P-E, Rennan, L., Wilson, O. B. and Nordgârd Bolas, H. M.
    , 2006, Relative permeability to wetting-phase water in oil reservoirs. Journal of Geophysical Research, v. 111, B12204.
    [Google Scholar]
  10. Teige, G.M.G., Hermanrud, C., and Rueslåtten, H.
    , 2011, Membrane seal leakage in non-fractured caprocks by the formation of oil-wet flowpaths. Journal of Petroleum Geology, 34, p. 1–9.
    [Google Scholar]
http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609.201700640
Loading
/content/papers/10.3997/2214-4609.201700640
Loading

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