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Case Study

 

Drilling in Tectonic Regions - Cusiana Field, Colombia

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Background:

  • Previous operators had failed to reach top reservoir due to excessive hole problems, cavings and stuck pipe. The new operator succeeded in getting their 1st exploration well into the reservoir, confirming the presence of hydrocarbons. However, the company struggled in subsequent appraisal and early development wells.

 

Technical Challenge:

  • Extreme wellbore stability seen in vertical wells

  • Tectonic environment on foothills of the Andes,

  • Initial appraisal wells taking over a year to drill,

  • Breakouts >45” on the long axis by 12 ½” gauge on the short axis,

  • Interbedded formations with strong sandstones in gauge

  • Active faulting, subsequent casing deformations,

  • Numerous sidetracks.

 

Solution:

  • Extensive review of hole problems, 

  • Identified mis-diagnosis of drilling problems,

  • Reviewed and developed lessons learned from an  analogue environment (Canadian Rockies),

  • Integrated team with Partners formed to provide recommendations for development well drilling, including;

    • optimised wellbore stability analysis,

    • improved mud systems

    • improved drilling practices

  • Instability problems minimised but not fully eliminated.

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Last & McLean 1996

Business Impact:

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  • Well costs initially came in at 5x to 6x the pre-drilling estimates,

  • Following continual focus on reducing wellbore stability and reducing drilling problems, NPT reduced from 47% (1993) to 27% (1996),

Cusiana OG Hole.png

Publications

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  1. Wu, B., Addis, M.A. and Last, N.C. 1998.  Stress Estimation in Faulted Regions: The Effect of Residual Friction. SPE/ISRM 47…, Proc. Eurock ’98 Conf., Trondheim, Norway, July 1998.

  2. Addis, M.A., Last, N.C. and Yassir, N.A. 1996.  Estimation of horizontal stresses at depth in faulted regions, and their relationship to pore pressure variations.  SPE Formation Evaluation, Vol. 11, No. 1, March, pp.11-18.

  3. Addis, M.A., Last, N.C. and Yassir, N.A. 1994.  The estimation of horizontal stresses at depth in faulted regions, and their relationship to pore pressure variations.  Proc. Eurock ‘94, Rock Mechanics in Petroleum Engineering, Delft, Nederlands, 29-31 August, pp.887-895.

  4. Addis, M.A., Last, N.R., Boulter, D, Ramisa-Roca, L. and Plumb, R.A. 1993. The quest for borehole stability in the Cusiana field, Colombia.  Oilfield Review, Vol. 5, No. 2/3, April/July 1993, pp.33-43.

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Related Publications

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  1. Osorio, J.G. and Lopez, C.F. 2009. Geomechanical Factors Affecting the Hydraulic Fracturing Performance in a Geomechanically Complex, Tectonically Active Area in Colombia. SPE 122315. SPE Latin American and Caribbean Petroleum Engineering Conference, Cartagena, Colombia, 31 May – 3rdJune 2009.

  2. Osorio, J.G., Penuela, G. and Otalora, O. 2008. Correlation Between Microseismicity and Reservoir Dynamics in a Tectonically Active Area of Colombia. SPE 115715. SPE Annual Technical Conference and Exhibition, Denver, Colorado, 21-24thSeptember 2008.

  3. Willson, S. M., Last, N. C., Zoback, M. D., & Moos, D. (1999, January 1). Drilling in South America : A Wellbore Stability Approach for Complex Geologic Conditions. SPE 53940. Latin American and Caribbean Petroleum Engineering Conference, 21-23 April, Caracas, Venezuela.

  4. Last, N.C., Harkness, R.M. and Plumb, R.A. 1998. From Theory to Practice: Evaluation of the Stress Distribution for Wellbore Stability Analysis in an Overthrust Regime by Computational Modelling and Field Calibration. SPE/ISRM 47209. SPE/ISRM Eurock ’98 Conference, Trondheim, Norway, 8-10 July 1998.

  5. Last, N.C. and McLean, M.R. 1996. Assessing the Impact of Trajectory on Wells Drilled in an Overthrust Region. SPE 30465. Journal of Petroleum Technology, July 1996, pp. 620-626.

  6. Last, N, C., Plumb, R. A., Harkness, R.M., Charlez, P., Alsen, J. and McLean, M.R. 1995. An Integrated Approach to Evaluating and Managing Wellbore Instability in the Cusiana Field, Colombia, South America. SPE 30464. SPE Annual Technical Conference and Exhibition, Dallas, USA, 22-25 October 1995.

  7. Skelton, J., Hogg, T.W., Cross, R. and Verheggen, L. 1995. Case History of Directional Drilling in the Cusiana Field in Colombia. IADC/SPE 29380. IADC/SPE Drilling Conference, Amsterdam, 28th February – 2nd March, 1995

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