A PRESSURE VESSEL FOR TRUE-TRIAXIAL DEFORMATION & FLUID FLOW DURING FRICTIONAL SHEAR

Transcription

1 A PRESSURE VESSEL FOR TRUE-TRIAXIAL DEFORMATION & FLUID FLOW DURING FRICTIONAL SHEAR Chris Marone, Brett Carperter, Derek Elsworth, Igor Faoro, Matt Ikari, Matt Knuth, André Niemeijer, Demian Saffer, and Jon Samuelson Rock & Sediment Mechanics Lab and Center for Geomechanics, Geofluids & Geohazards, The Pennsylvania State University, USA

2 Rock & Sediment Mechanics Lab and Center for Geomechanics, Geofluids & Geohazards Outline Lab Pressure Vessel for True Triaxial Deformation & Fluid Flow Current Research

3 Biaxial Load Frame + Pressure Vessel = True Triaxial Stress State Applied Stresses to 300 MPa, Simultaneous fluid flow and shear Pore and Confining Pressures to 70 MPa (10K psi) Deformation rates of 0.01 µm/s to cm/s Fluid composition: H 2 0, brine, CO 2, etc.

4 QuickTime and a YUV420 codec decompressor are needed to see this picture.

5 QuickTime and a YUV420 codec decompressor are needed to see this picture.

6 True Triaxial Stress State, Double Direct Shear Porous Frits for fluid access Latex Jacket

7 Latex Jacket

8 True Triaxial Stress State σ 1 Confining Pressure is σ 3 σ 2 σ 2

9 Fluid flow normal and parallel to shear direction True Triaxial Stress State, Double Direct Shear Pp 2 DCDT Pore Press. 1 Drained or Undrained QuickTime and a TIFF (LZW) decompressor are needed to see this picture. Pore Press. 2 DCDT

10 Permeability Normal to shear, Synthetic Fault Gouge Shear velocity perturbations Strain localization Connection to dilation/compaction

11 Permeability Normal to shear, Synthetic Fault Gouge Shear velocity perturbations Strain localization Connection to dilation/compaction

12 Friction p956 Permeability (m 2 ) Permeability Normal to shear, Synthetic Fault Gouge Shear velocity perturbations Strain localization Connection to dilation/compaction Shear Displacement (mm)

13 True Triaxial Stress State, Single Direct Shear

14 True Triaxial Stress State, Single Direct Shear

15 a b c

16 FLUID FLOW PARALLEL TO SHEAR; Triaxial, Diorite synthetic fault Wear & Gouge Formation Reduces Fault Parallel Permeability

17 FLUID FLOW PARALLEL TO SHEAR; Triaxial, Diorite synthetic fault Wear & Gouge Formation Reduces Fault Parallel Permeability Consequences for Pore Fluid Chemistry

18 Porosity (%) Salt as an Analog for Chemical-Mechanical Effects Rapid compaction through intergranular pressure solution increasing stress Friction coeff. μ Rapid re-strengthening (healing) of synthetic fault gouges (& possibly sealing!) compared to quartz gouges saturated moist+muscovite dry & quartz Time (s) Hold time (s) Mechanical-chemical interactions occur at laboratory temperatures and timescales Permeability (m 2 ) coarse-grained fine-grained Porosity (%) Leading to permeability loss as a function of porosity & grain size

19 Current Research Areas Mechanical & transport properties of geomaterials Permeability measurements normal and parallel to shear Drained and undrained poromechanics Frictional properties, fracture strength Effect of dynamic stressing on permeability, strength, and constitutive properties Rock, fault gouge, clay, granular materials, mudrocks Reactive transport, Physicochemical deformation mechanisms Acoustic Emissions and Elastic properties

20 Fault Seal as a function of shear Applications Permeability evolution with strain and deformation, response to reservoir deformation Compaction, shear, overpressure, dilatancy strengthening The role of fabric development and shear localization in fluid compartmentalization and reservoir overpressure Poroelastic properties and effective stress Acoustic signature of strain localization Elastic properties and poroelastic anisotropy

21 Elastic Parameters, Vp, Vs, Acoustic Emissions During True-Triaxial Shear

22 Acoustic Emissions during biaxial shear experiment Mair, Marone & Young, BSSA, 2007

23 AE during biaxial shear experiment Mair, Marone & Young, BSSA, 2007