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Pore Pressure and Fracture Gradient analysis

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Pore Pressure and Fracture Gradient estimation underpins well design, well integrity and for safe drilling, as well as contributing to hydrocarbon volume estimation in place and seal integrity limits.

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The standard pore pressure analysis models, which were developed to assess the amount of overpressures based on undercompaction, are used for exploration and appraisal wells, and which can be expanded to 3D seismic-based analysis. Additionally, customised approaches are used to assess overpressures in regions where other overpressure generation mechanims are suspected.

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Addis & Yassir  have experience of pore pressure prediction across the globe in passive and tectonic environments. The mechanisms giving rise to overpressure have been investigated to understand where to use the industry standard models, and where customised approaches are required for meaningful pore pressure prediction.

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Pore pressures and fracture gradients are linked - so overpressures are accompanied by higher fracture gradients, conversely, depleted reservoirs commonly experienced reduced fracture gradients.

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In compressive tectonic regions, the standard models are not useful for predicting pore pressures or fracture gradients, as a result customised approaches have been developed by Addis & Yassir and adopted for predicting the pressures in the highlands of PNG.

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Addis & Yassir have also driven regional basin hydrodynamic analysis which has been used to characterise reservoir pore pressure distributions across different structures and fields.

Well Integrity & PP-FG - Fjaagesund 2015

Fjaagesund (2015)

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Najwa's Pore Pressure Mechanisms.png

Patents

  1. Yassir, N. and de Bree, P. May 2009. Stress Based Pore Pressure Prediction. US patent number 7529625.

 

Publications

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  1. Yassir, N. and Savitski, S. 2006. Horizontal stresses in Cretaceous sediments in the UK Central Graben: relationship with Jurassic overpressure. In-Situ Rock Stress: Measurement, Interpretation and Application, Ming Lu et al (eds.), p. 235-240. Presented at the Stress Symposium, Trondheim 19-21 June.

  2. Yassir, N, and Addis, M.A. 2002. Relationships between pore pressure and stress in different tectonic settings, in A.R. Huffman and G.L. Bowers, eds., Pressure Regimes in sedimentary basins and their prediction: AAPG Memoir 76, pp.79-88.

  3. Hennig, A., Yassir, N., Addis, M.A., and Warrington, A. 2002. Pore pressure estimation in an active thrust region and its impact on exploration and drilling. in A.R. Huffman and G.L. Bowers, eds., Pressure Regimes in sedimentary basins and their prediction: AAPG Memoir 76, pp.89-105.

  4. Addis, M.A. and Hennig, A. 1998.  Pore pressure evaluation: differentiating between overpressure and wellbore instability. AADE workshop on “Pore Pressure Regimes in Sedimentary Basins”, Del Lago, September 1998.

  5. Hennig, A., Yassir, N. and Addis, M.A.1998.  Pore pressure determination in a compressive tectonic region, Hides field PNG. Proc. AADE workshop on “Pore Pressure Regimes in Sedimentary Basins”, Del Lago, September 1998.

  6. Marken, C., Bjørkevoll, K.s., Rommetveit, R. and Addis, M.A. 1998. Well Control planning with ECD simulation in advanced wells. Proc. Offshore West. Australia ’98 Conf., March 31-April 2, 1998.

  7. Yassir, N. A., 1998. Prediction of overpressuring in different stress regimes. Proceedings of Overpressures in Petroleum Exploration Workshop, Pau, April 1998.

  8. Yassir, N. A. 1997. Geomechanical controls on overpressuring: implications for pore pressure prediction in compressional basins. Geofluids II, Contributions to the Second International Conference on Fluid Evolution, Migration and Interaction in Sedimentary Basins and Orogenic Belts, Belfast, N. Ireland, March 1997, J. P. Hendry et al (eds.): 235-238.

  9. Otto, C. and Yassir, N. A. 1997. Hydrodynamic assessment of fault seal integrity: ramifications for exploration and production. Geofluids II, Contributions to the Second International Conference on Fluid Evolution, Migration and Interaction in Sedimentary Basins and Orogenic Belts, Belfast, N. Ireland, March 1997, J. P. Hendry et al (eds.): 129-132.

  10. Yassir, N. A. and Otto, C. 1997. Hydrodynamics and fault seal assessment in the Vulcan Sub-basin, Timor Sea. APPEA Journal, 37 (I): 380-389.

  11. Yassir, N. A. and Bell, J. S. 1996. Abnormally high fluid pressures and associated porosities and stress regimes in sedimentary basins. SPE Journal of Formation Evaluation, 11 (1): 5-10. Also in Eurock '94, Rock Mechanics in Petroleum Engineering: 879-886

  12. Yassir, N. A. (1995). Pore- and fracture-pressure determinations: effective stress approach: Discussion. SPE Journal of Petroleum Technology, October 1995: 913.

  13. Yassir, N. A. and Bell, J. S. (1994) Relationships between pore pressure, stresses and present day geodynamics in the Scotian Shelf, offshore eastern Canada. American Association of Petroleum Geologists Bulletin, 78 (12): 1863-1880

  14. Yassir, N. A. and Rogers, A. L. (1994) Overpressures, fluid flow and stress regimes in the Jeanne d'Arc Basin, Canada: Reply. Bulletin of Canadian Petroleum Geology, 42.

  15. Yassir N. A. and Rogers A. L. (1993) Overpressures, fluid flow and stress regimes in sedimentary rocks of the Jeanne d'Arc Basin, Canada. International Journal of Rock Mechanics, Mining Sciences and Geomechanical Abstracts 30 (7): 1209-1213. Also Proceedings of the 34th U.S. Symposium on Rock Mechanics, Haimson, B. (ed.): 379-382.

  16. Rogers, A. L. and Yassir, N. A. (1993) Hydrodynamics and overpressuring in the Jeanne d'Arc Basin, offshore Newfoundland, Canada: possible implications for hydrocarbon exploration. Bulletin of Canadian Petroleum Geology 41 (3), p. 275-289.

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