Low pressures to high pressures - how regional overpressure mapping helps find trapped hydrocarbons

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Dennis Garrison
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1 Finding Petroleum Conference London: January 2010 Low pressures to high pressures - how regional overpressure mapping helps find trapped hydrocarbons Richard Swarbrick & Stephen O Connor GeoPressure Technology

3 Principal Messages Overpressure mapping is an underutilised technology Low overpressure can be highly significant for reserves determination and unrecognised potential High overpressure controls exploration risk for breached traps Regional overpressure mapping projects have now been completed in NW Europe and in progress elsewhere

4 RELATIONSHIPS ARE KEY TO PRESSURE PRESSURE STRESS

5 Depth Lateral drainage and pressure regressions Pressure Near Normally Pressured Shale O/P gradient (rapid loading) Water Gas Water Overpressure RESERVOIR PRESSURE > SHALE PRESSURE Overpressured Reservoirs

6 Low Pressure Relationships Interpret reservoir pressure data Assign overpressure values for each reservoir Map overpressures for each reservoir If reservoir continuous contour values Establish possible hydrodynamic flow directions Examine well field data Establish tilt on hydrocarbon-water contact Revise reserves

7 Distribution Map of Overpressures Forties Forties Formation Update of CNS (2003) Map Contours of overpressure in psi Nelson Field 13 Depleted HC in wells Cat 4 19 Cat 3 13 Cat No Palaeocene Data Channel Axis

8 Central Graben Pressure Study O/P < O/P 50 psi < 50 psi Andrew Sandstone limit Hydrodynamic flow directions Distribution Map of Overpressures Andrew Formation Contours of overpressure in psi O/P > 2000 psi Close to shale pressures?

9 EXPLORATION SIGNIFICANCE

10 Potential to fill to structural spill point Hydrostatic OWC/ FWL Simple Anticline: Pressure- Depth plot for oil accumulation

11 Well A Oil Down To Upside potential to spill point Proven Reserves 30 MMBO Possible Reserves + 30 MMBO

12 Appraisal Well B Well A OWC/FWL DRY HOLE Proven Reserves 40 MMBO

13 DECISION TIME! Assess reserves not enough to justify development Relinquish acreage? Farm out/sell assets to smaller/leaner company? Examine other possibilities and look at regional pressure distribution?

14 Well B Well A DRY HOLE Regional overpressure distribution suggests lateral drainage, with outflow to right

15 Well B Well A Well C OWC/FWL OIL & WATER

16 Hydrodynamic Model o o o Common Oil Leg o x Well A Well B x + + x + x + Well C Variable water legs Minimum pressure data to define reserves

17 Well B Well A Well C Proven Reserves 70 MMBO OIL & WATER

18 Implications Hydrodynamic model influences reserves distribution, volumes and reservoir connectivity Hydrodynamic reservoirs are to be found in many overpressured basins we just have not properly looked yet. GeoPressure Technology, an Ikon Science company, specialises in identifying hydrodynamic aquifers (lateral drainage)

19 High Pressure Relationships Interpret well pressure data Assign overpressure values for each reservoir Map overpressures for each reservoir Similar values are in same pressure cell Define pressure cell boundaries (not trivial) Map aquifer seal capacity/effective stress Identify trap leak points and protected traps Establish seal breach risk and exploration strategy

20 LEAKING TRAP PROTECTED TRAP after Seldon & Flemings,

21 LEAKING TRAP PROTECTED TRAP Overpressure after Seldon & Flemings, 2005

22 AQUIFER SEAL CAPACITY Structural Crest Aquifer Seal Capacity Hydrostatic Gradient Aquifer Gradient Minimum Stress Hydrocarbon seal capacity Determined from RFTs, etc Determined from 2 algorithms

23 22/30a-1 22/29-6s2 23/26a /30b-4 22/24b-8 30/1c-2A 22/ / /01f- 8 22/30b- 15Z 23/26b- 8 23/ /26b-15 22/ /26b /07a-2 21/20a-1 22/30b /28a-1 23/ /16d- 6 29/5a-3 22/08a-3 15/30-12 NO1/6-7 22/27a- 1 30/1c-4 29/4a-2 22/25b- 2 29/05b- 4Z NO7/7-2 22/23b-6 29/5a-5 29/08b- 5 22/30a-2 22/22b- 4 21/ /01c- 3 22/28a- 4 29/10a-2 22/24d /2a-2 29/10-3 sti 22/24a-A1Z 22/30c-10 29/09c- 4 29/05a- 1Z 23/ /08a- 3 15/23a-12 22/30a- 6 22/ /24a-2 30/7a-7 29/05b-F1 21/ /11b-3 22/24b-9 23/22b-4 30/07a-P1 30/07a- 8 39/02-2Z 21/ /8a-4 21/ /7a-12 22/30c-13 29/07a- 7 21/01a / /07a- 6 29/08a- 4 23/11-4 NO3/4-1 22/ /07a-4 15/22-D1A 29/07a- 5 21/ / /11b- 4 22/30a / / /27-10 Top Reservoir Seal Capacity (psi) 3000 Aquifer Seal Top Reservoir Capacity Seal Top Capacity Reservoir (85 wells) Offers a risking strategy psi High Risk Low Risk Well

24 Primary Eruption: 29 th May + secondary eruption 2nd June June 2006 Courtesy of Bakrie Media Centre

25 Concluding Remarks Overpressure mapping is a valuable exploration tool Hydrodynamic systems are not well recognised worldwide exploration opportunity High overpressure represents an exploration and drilling challenge Integration of pressure data into the finding petroleum workflow is key to success

26 Finding Petroleum Conference London: January 2010 QUESTIONS

For personal use only

For personal use only ASX ANNOUNCEMENT 29 October 2014 ABN: 65 078 301 505 288 Stirling Street Perth WA 6000 PO Box 8260 PBC WA 6849 Tel: +61 8 9227 3240 Fax: +61 8 9227 3211 www.norwestenergy.com.au Planning underway to drill