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Sub-horizontal drilling: remedy for underperforming Rotliegend gasfields, L13 block, central offshore Netherlands

  • Harm W. Frikken

Abstract

The first development well in the L13-FE gasfield showed a rapid production decline. Material balance data indicated less than 10% of the expected volumetric reserves to be connected. This poor connectivity is thought to be due to compartmentalization by sealing strike-slip faults, as indicated by faint lineations observed on seismic attribute maps. The presence of only a limited number of scattered, stratigraphically isolated, prolific layers within an overall rather tight and layered reservoir, resulted in a poor overall vertical permeability, which also contributed to the disappointing well performance. The vertical well was subsequently sidetracked sub-horizontally with the aim to connect a larger number of the scattered prolific sands, different fault-compartments and possible open fracture systems. Graded rocksalt drilling mud was used in order to minimize formation impairment. During drilling of the sub-horizontal section numerous problems were encountered due to mechanical failures and the heterogeneous, layered nature of the reservoir. A significant number of prolific, scattered sand layers were encountered and the presence of a small scissor-type fault was recognized from log correlations. Considering that only some 60% of the well could be completed due to mechanical problems, the well is now producing at acceptable rates. The attempt to challenge such a geologically complex, labyrinth-type reservoir by sub-horizontal drilling, has been cost-effective and successful. However, it is recommended that slimhole, sub-horizontal drilling in this type of layered reservoirs should be applied with caution.

Key words

drilling mud layered reservoir small field strike-slip faults sub-horizontal well 

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References

  1. Biddle, K.T. & N. Christie-Blick 1985 Strike-slip deformation, basin formation and sedimentation — Soc. Econ. Paleont. Mineral. Spec.Publ. 37:386ppGoogle Scholar
  2. Economides, M.J., K.B. Naceur & R.C. Klem 1991 Matrix stim-ulation method for horizontal wells — J. Petroleum Techn. 43: 854–861Google Scholar
  3. Frikken, H.W & J.B. Stark 1993 Character and performance of small Rotliegend gas reservoirs, Central Offshore Netherlands. In: North Sea oil and gas reservoirs III, Proceedings of the 3rd North Sea Oil and Gas Conference, Norwegian Institute of Technology, Trondheim, Norway, November 30 — December 2, 1992 — Kluwer Academic Publishers, Dordrecht: 41–50Google Scholar
  4. Hancock, PL. 1985 Brittle microtectonics: principles and practice — J. Struct. Geol. 9: 437–457CrossRefGoogle Scholar
  5. Kuchuk, F.J. & P.A. Goode 1988 Pressure transient analysis and inflow performance for horizontal wells — Soc. Petroleum Eng. (SPE) Paper 18300Google Scholar
  6. McDonald, J.A. & D.C. Buller 1992 The significance of formation damage caused by the adsorption of oil-based mud surfactant — J. Petroleum Sci. and Engin. 6: 357–365CrossRefGoogle Scholar
  7. Renard, G. & J.M. Dupuy 1991 Formation damage effects on horizontal-well flow efficiency — J. Petroleum Techn. 43: 786–789Google Scholar
  8. Weber, K.J. & L.C. Van Geuns 1989 Framework for constructing clastic reservoir simulation models — Soc. Petroleum Eng. (SPE) Paper 19582Google Scholar

Copyright information

© Kluwer Academic Publishers 1996

Authors and Affiliations

  • Harm W. Frikken
    • 1
  1. 1.Nederlandse Aardolie Maatschappij BV (Corporate Planning and Development)Assenthe Netherlands

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