Best Practice in Pore Fluid Pressure and Fracture Pressure Prediction
|Prof. Dr Richard Swarbrick (Swarbrick GeoPressure Consultancy, Durham, United Kingdom)|
|Geology – Geological Modeling|
|10 CPD points|
CARBONATES DRILLING INTERPRETATION OFFSHORE PORE PRESSURE SEDIMENT SEDIMENTOLOGY SHALE TECTONICS WELLS
All wells drilled require a pre-drill prediction of pore fluid and fracture pressures that defines the ‘drilling window’. This course explains the objectives, methods and uncertainties of prediction, based on extensive global experience. The necessary understanding of the geological/geophysical context of abnormal pressures leading to standard algorithms will be provided. Part of the challenge is terminology and contrasting display methods of geoscience and operations/drilling groups. Both approaches are necessary and investigated in interactive exercises, which will form an essential component of the course.
Upon completion of the course the participants will be able:
- To know the elements involved in well planning that relate to pore fluid and fracture pressures;
- To understand the causes and to recognize the occurrence of abnormal pressures in the subsurface;
- To know how to collect appropriate data to solve standard equations for pressure prediction;
- To comprehend the uncertainties in predictions from data selection as well as the variation in prediction methods and approaches;
- To understand how to communicate between geoscience and operations/drilling personnel in relation to pressure prediction.
Session 1: Introductions; Objectives; Terminology; What is “Best Practice”?
Session 2: Data types and displays as pressure-depth and equivalent mud weight-depth plots. Defining the "drilling window" and input to well planning. Importance of context: prediction of lithology and its influence on pressure profiles.
Exercise One: Context for frontier well proposal – EAGE-1;
Exercise Two: Lithological prognosis for EAGE-1.
Session 3: Pore fluid pressure prediction: methodology around vertical effective stress estimation. Estimating shale pressure gradient using the “Swarbrick Method”.
Exercise Three: Determining the Fluid Retention Depth.
Pore pressure prediction using shales; determining the overburden pressure; selecting a Normal Compaction Trend (NCT); Equivalent Depth (Effective Stress) and Eaton models; pore pressure from seismic velocities.
Exercise Four: Developing a Bowers Transform for solving velocity to vertical effective stress. Solving Terzaghi equation for pore pressure from vertical effective stress.
Exercise Five: Pore pressure prediction from seismic interval velocities for EAGE-1.
Session 4: Recap of Day One. Using velocity-density cross-plots to identify overpressure generating mechanisms; lateral drainage and lateral transfer. Limitations of existing methods. Pore pressure prediction in carbonates. Revision of pore fluid pressure prediction.
Best practice in pore pressure prediction – a review.
Session 5: Fracture pressure prediction: Determination from local-derived LOT data, where available. Using published algorithms related to overburden;
Exercise Six: Estimate of fracture pressures from standard Leak-Off test (LOT).
Session 6: Understanding how fracture pressure is coupled to pore fluid pressure; Lahann & Swarbrick fracture gradient model, compared to Matthews & Kelly method. Group exercise using LOT data from four wells to develop solution for EAGE-1.
Best practice in fracture pressure prediction – a review.
Session 7: Pore fluid pressure – fracture pressure (PP-FG) and the requirements for well planning. Determining Min-Expected-Max ranges. Generating and communicating using an Equivalent Mud Weight (EMW) vs Depth plot. Common pitfalls.
Session 8: Conclusions. Best practice in conventional hydrocarbon plays; Best practice in “unconventional” plays. Confidence matrix for pore fluid pressure.
Note: Sessions may be adapted to include material relevant to the local area.
The course is designed for geoscientists (geophysics, petrophysics, geomechanics), engineers (operations, reservoir and drilling) and managers.
Participants should have a working knowledge of oilfield operations, including the data types that are used in defining the geology of the subsurface as well as the components of drilling wells.
About the instructor
Professor Richard Swarbrick is currently an independent consultant for the oil and gas industry specialising in sub-surface pressures, whilst retaining research and teaching interests at Durham University. After completing a BSc in Geology from Durham and PhD in sedimentology/tectonics at Cambridge University Richard worked as a petroleum geologist and exploration supervisor for Mobil for ten years from 1979. During that time he worked on both exploration and production assignments in UK and Alaska Division, USA.
In 1989 he moved back to academia, and began teaching petroleum geology, basin studies and related courses at Durham. Developing a research interest in subsurface pressures, from 1994 to 2001 Richard was the principal investigator of GeoPOP (GEOsciences Project into OverPressure), a multi-disciplinary research group funded by 17 oil/gas companies. The research led to many publications related to overpressure mechanisms, pore pressure prediction methods, modeling pressure through time in basins, and the influence of overpressure on the petroleum system. He was involved in GeoPOP3 at Durham University from 2011-2015.
In 1997 Richard had founded the university spin-out company, GeoPressure Technology, producing niche software, later expanded into training, consultancy and multi-client pressure studies. From a back office in the Geological Sciences department the company grew to employ more than 20 geoscientists, and is now part of the Ikon Science Group. Richard left the company in 2013, but continues to teach pressure courses in many oil centres around the world, either as open courses or in-house training companies. He consults widely and continues to present conference papers and publish articles relating to sub-surface pressures.
Richard is a Fellow of Geological Society of London since 1982, and member of EAGE, AAPG and PESGB.
- Osborne, M.J. & Swarbrick, R.E., 1997. Mechanisms for generating overpressure in sedimentary basins: A re-evalution.AAPG Bulletin, v. 81, p. 1023-1041.
- Bell, D.W., 2002. Velocity estimation for pore-pressure prediction. In: Pressure regimes in sedimentary basins and their predictions. (Ed. Huffman, A.R. & Bowers, G.L.)AAPG Memoir, p. 217-233.
- Swarbrick, R.E., 2012. Review of pore pressure prediction challenges in high-temperature areas. The Leading Edge. v. 31, p. 1288-1294.
- Swarbrick, R.E. & Lahann, R.W., 2016. Estimating pore fluid pressure - stress coupling.Journal of Marine & Petroleum Geology, v. 78, p. 562-574.
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