Estimation of fracture flow parameters through numerical analysis of hydromechanical pressure pulses

Journal Article · Sun Mar 16 04:00:00 EDT 2008 · Water Resources Research

DOI:https://doi.org/10.1029/2008WR007015· OSTI ID:950850

Cappa, F; Guglielmi, Y; Rutqvist, J; Tsang, C -F; Thoraval, A

The flow parameters of a natural fracture were estimated by modeling in situ pressure pulses. The pulses were generated in two horizontal boreholes spaced 1 m apart vertically and intersecting a near-vertical highly permeable fracture located within a shallow fractured carbonate reservoir. Fracture hydromechanical response was monitored using specialized fiber-optic borehole equipment that could simultaneously measure fluid pressure and fracture displacements. Measurements indicated a significant time lag between the pressure peak at the injection point and the one at the second measuring point, located 1 m away. The pressure pulse dilated and contracted the fracture. Field data were analyzed through hydraulic and coupled hydromechanical simulations using different governing flow laws. In matching the time lag between the pressure peaks at the two measuring points, our hydraulic models indicated that (1) flow was channeled in the fracture, (2) the hydraulic conductivity tensor was highly anisotropic, and (3) the radius of pulse influence was asymmetric, in that the pulse travelled faster vertically than horizontally. Moreover, our parametric study demonstrated that the fluid pressure diffusion through the fracture was quite sensitive to the spacing and orientation of channels, hydraulic aperture, storativity and hydraulic conductivity. Comparison between hydraulic and hydromechanical models showed that the deformation significantly affected fracture permeability and storativity, and consequently, the fluid pressure propagation, suggesting that the simultaneous measurements of pressure and mechanical displacement signals could substantially improve the interpretation of pulse tests during reservoir characterization.

• Research Organization: Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
• Sponsoring Organization: Earth Sciences Division
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 950850
• Report Number(s): LBNL-1664E
• Journal Information: Water Resources Research, Journal Name: Water Resources Research; ISSN WRERAQ; ISSN 0043-1397
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES
BOREHOLES
CARBONATES
DEFORMATION
DIFFUSION
FRACTURES
HYDRAULIC CONDUCTIVITY
HYDRAULICS
NUMERICAL ANALYSIS
ORIENTATION
PERMEABILITY
SIMULATION