1. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Stress determination and pore pressure measurements performed at the Meuse/Haute-Marne Underground Laboratory Y.WILEVEAU, J. DELAY Andra – National Radioactive Waste Management Agency, Bure, France

2. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Overview Part 1 Methodology for regional stress determination Hydrofrac, HTPF and Sleeve fracturing Data examples Stress profile Part 2 Pore pressure measurement in clay formation Pressure profile in the argillite Comparison and open question

3. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Geological setting on Bure’s URL

4. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Methodology for stress determination at the Bure site From shafts Paleostress Convergence measurements on several sections Vertical Mine by Test experiment in the main Shaft of the URL From boreholes Deformations of vertical borehole walls Breakouts and induced fractures in inclined boreholes (Etchecopar, 1997) Classical hydro-fracturing (Haimson, 1993) Hydraulic tests on Pre-existing Fractures (HTPF method, Cornet, 1986) Sleeve fracturing and Sleeve reopening (Desroches, 1999)

5. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Convergence measurements in the Oxfordian limestones  H oriented at N155°E accuracy : 0,1 mm on a 6m diameter of the shaft maximum convergence measured :  2mm horizontal stress anisotropy K=  H /  h : between 1.4 et 1.8 HH Section at 223m HH Section at 375m HH Section at 415m

6. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger UBI analysis and wall morphology (example for EST 204 borehole) Breakouts appears in the clay-rich area (less compressive strength) High dependence on the fluid for drilling (water based mud for EST204) oil based mud give us better well stability

7. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger MDT tool (specific configuration for inclined boreholes) Hydraulic fracturing tests in Bure Downhole pump Straddle packer Pressure record during a micro-hydraulic fracturing test Fracture initiation Closure pressure of the induced fracture (Detail of the first hydraulic fracturing cycle) Closure pressure Breakdown pressure Closure pressure determined from the square root of the shut-in time Closure pressure Induced fractures detected and oriented on FMI image

8. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger General situation of hydraulic fracturing tests at Bure Site 29 successful tests in 5 boreholes : - 6 in Oxfordian - 17 in C.Oxfordian - 6 in Dogger

9. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger In-situ stress in Oxfordian  H oriented in N155°E Slight rotation at the base of Oxfordian unit  h  8 MPa (average value) Magnitude (MPa)  H orientation (°/North) HH hh

10. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Induced fracture at 467m (horizontal) Induced fracture at 471m (horizontal) Hydraulic fractures mined back during the sinking of the shafts (in clay formation)

11. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Top view of EST205 borehole at 499m on the ground ……but vertical at 499m depth !!! HH hh UBI – acoustical logging after micro-hydraulic tests at depth 499m in EST205 Fractures initiated during Hydrofrac (  H direction)

12. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Vertical stress measured in the Dogger (HTPF method) Direct measurement :  v = 14,7 MPa at 655 m depth + Others Pre-existing Fractures have been tested in the argillites (  v  12,0 MPa) Selection of a pre-existing lignite layer at 655m depth : possibility to measure  v by HTPF method FMI after test Induced fracture by packers FMI before test

13. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Q=0 Stress regime: Extension 123123 Q=0.5 Stress regime: Extension Q=1 Stress regime: Strike-slip Q=1.5 Stress regime: Strike-slip Q=2 Stress regime: Strike-slip Q=2.5 Stress regime: Compression Q=3 Stress regime: Compression Influence of the shape of the stress tensor on the breakout orientation (from Desroches and Etchecopar, 2005).. assuming constant orientation of the main stresses

14. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Ordering the stresses by breakout analysis in the argillites (from Desroches and Etchecopar, 2005) Q=0.5 Q=1 Q=2 Q=3 Q=2.5 Q=1.5 Q=0 2.3 >Q>1.8  H>  V=  h  h N 60-65 In agreement with hydrofrac results:  h =  V Deviated borehole (60°/vert)

15. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Variation of  h with lithology : Orientation Orientations are roughly constant in the Callovio-Oxfordian and in the Dogger Orientations in the Oxfordian turn 40 degrees when approaching the contact with the Callovio-Oxfordian  H  N150°E : Major tectonic shortening during the last Alpine Orogeny

16. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger σ h and σ v magnitudes : variation with lithology ! Huge difference between limestone and shales σ h magnitudes are very similar in the limestones surrounding the clays σ h is  3 in the limestones and  2 in the middle of the clays formation And what’s about σ H ? hh VV Weight of sediments Depth m. Limestone Shale ? HH vv hh

17. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Sleeve fracturing and sleeve reopening in the clay formation A special test has been performed at 504m in a sub-horizontal well In order to estimate  H

18. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Sleeve reopening – Identification of packer pressure for opening of the fracture UBI before test UBI after test Estimation of σ H 12.7 MPa ≤  H ≤ 14.8 MPa  H – P 0 = 3(  v – P 0 ) – (P r – P 0 )

19. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Maximum horizontal stress  H estimation by sleeve reopening breakouts analysis shaft convergence  H estimated :  14-15 MPa Approximately constant with depth

20. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger EPG – Long term monitoring at the laboratory location

21. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger EPG – pressure profile In situ stress profile

22. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Conclusions To determine the complete state of stress in a lithologic sequence  a combination of methods is required Hydraulic fracturing and image analysis in deviated boreholes are perfectly complimentary  Such a combination allowed the determination of the complete state of stress In the studied sequence, there is a large difference in the state of stress in the limestones and that in the argillites The pore pressure profile looks like to stress profile but ….. Is that a common behavior? How could one predict it?

23. - D TR ADPE 06-0607/ A © FORCE shale seminar 18 &19 Sept. 2006 - Stavanger Thank you for your attention !