The Influence of Shear and Deviatoric Stress on the Evolution of Permeability in Fractured Novaculite and Diorite

Transcription

1 Igor Faoro, Andre Niemeijer, Chris Marone, Derek Elsworth The Influence of Shear and Deviatoric Stress on the Evolution of Permeability in Fractured Novaculite and Diorite Department of Energy and Geo-Environmental Engineering Penn State University Supported By: DOE-BES-DE-FG02-00ER15111 & DOE-Geothermal-DE-FG36-04GO14289 Erice 2007

2 Project Relevance Feasibility of Oil Recovery from Underground Reservoirs Interconnected Fractures Networks Development of Groundwater Resources Recovery of Steam from Geothermal Reservoirs Coso Geothermal Field

3 Outline Test Description Experimental Configuration Equipment Used Profile Mapping Experimental Results Mechanical Behavior Hydraulic Behavior Profile Mapping Chemical Behavior Discussion and Conclusions

4 Experimental Arrangement 1 1 The Influence of Shear and Deviatoric Stress on the Evolution of Permeability in Fractured Novaculite and Diorite, I. Faoro, A. Niemeijer, C. Marone, D. Elsworth. In review, JGR.

5 Experimental Arrangement

6 Experimental Configurations Diorite Samples 1 Novaculite and Diorite Thickness [mm] 22.4 Width [mm] 45 Length [mm] 50 Matrix Porosity [%] <0.01 Total Normal Stress [MPa][ Confining Pressure [MPa][ Differential Pressure [MPa] Novaculite Samples 1 By Measuring: Flow Rate and Mass Rate to Determine Permeability and Hydraulic Aperture Changes 1 The Influence of Shear and Deviatoric Stress on the Evolution of Permeability in Fractured Novaculite and Diorite, I. Faoro, A. Niemeijer, C. Marone, D. Elsworth. In review, JGR.

7 Profile Mapping Diorite 45 * 50 mm Pre -Test Novaculite 45 * 50 mm Diorite 45 * 70 mm Novaculite 45 * 70 mm

8 Change in Shear Stress with the Shear Displacement at Different Applied Effective Normal Stresses Values σ n [MPa] Pc [MPa] P P P P σ n [MPa] Pc [MPa] P P P P P

9 Change in Friction Coefficient with the Shear Displacement at Different Applied Effective Normal Stresses Values σ n [MPa] Pc [MPa] P P P P σ n [MPa] Pc [MPa] P P P P P

10 Change in Peaks and Residual Shear Stress Values with the Applied Effective Normal Stress Values 1 15 Diorite Shear Stress [MPa] Peak-values Shear Stress Residual-values Shear Stress Normal Stress [MPa] Shear Stress [MPa] Novaculite Peak-values Shear Stress Residual-values Shear Stress Normal Stress [MPa]

11 Permeability and Hydraulic Aperture Q = d w 3 12μ dp dl k = Q μ l ρ g A T

12 Change in Permeability with the Shear Displacement at Different Applied Effective Normal Stresses Values σ n [MPa] Pc [MPa] P P P P σ n [MPa] Pc [MPa] P P P P P

13 Change in Hydraulic Aperture with the Shear Displacement at Different Applied Effective Normal Stresses Values σ n [MPa] Pc [MPa] P P P P σ n [MPa] Pc [MPa] P P P P P

14 Profile Mapping Diorite 45 * 50 mm Post -Test Novaculite 45 * 50 mm Diorite 45 * 70 mm Novaculite 45 * 70 mm

15 Change in Concentration of Major Ions with the Shear Displacement at Different Applied Effective Normal Stresses Values 35 Diorite [Mg] p1083 [Mg] p1159 & p1082 [Mg] p1081 [K] p1083 [K] p1159 & p1082 [K] p Novaculite [Mg] p1079 & p1101 [Mg] p1114 [Mg] p1168 & p1080 [Si] p1079 & p1101 [Si] p1114 [Si] p1168 & p1080 Concentration [ppm] Shear Displacement [mm] Concentration [ppm] Shear Displacement [mm] σ n [MPa] Pc [MPa] P P P P σ n [MPa] Pc [MPa] P P P P P

16 Discussion and Conclusions Summary: In diorite and novaculite initial values of permeability range between and 0.5 x m 2 ; (15-20 μm); After shearing in diorite: reduction in permeability of three orders of magnitude (to 2 μm), while in novaculite two (to 5μm); Surface roughness is the parameter controlling the responses; The dependence of the fractures to the initial roughness and applied stress conditions has been confirmed.

17 Future Works Amplitude [MPa] Frequency 1/period [Hz] Duration [sec] Time Between Series [min] Number of Series rep. 3 times rep. 3 times rep. 3 times rep. 3 times rep. 3 times rep. 3 times

18 Change in Permeability with the Applied Frequency Paired Sample p1397, Frequency, A: 0.4 MPa, D: 120 sec 4.E-08 Perm [m/sec] 3.E-08 2.E-08 1.E-08 pre peak post delta 0.E Log Frequency [Hz] Paired Sample p1397, Frequency, D: 240 sec, A: 0.4 MPa 1.E-06 Log Perm [m/sec] 1.E-07 1.E-08 1.E Frequency [Hz] pre peak post delta

19 QUESTIONS? Thank you.

20 QUESTIONS? Thank you.