Assessing hydrofracing success from earth tide and barometric response

Area of Science:

• Geology
• Hydrogeology
• Environmental Science

Background:

• Understanding fracture connectivity is crucial for assessing groundwater flow and transport properties.
• Previous methods for identifying fracture networks were complex and less direct.
• Crystalline rock settings present unique challenges for characterizing subsurface fractures.

Purpose of the Study:

• To present a simple methodology for assessing hydrofracturing success.
• To identify fracture connectivity between neighboring boreholes post-hydrofracturing.
• To analyze water-level barometric and tidal responses for fracture characterization.

Main Methods:

• Collected water levels and barometric pressure heads at two wells (27 m apart) before and after hydrofracturing.
• Analyzed distinct barometric and tidal signatures in individual wells.
• Conducted aquifer testing to verify well connectivity.

Main Results:

• Prior to hydrofracturing, wells exhibited significantly different barometric and tidal signatures.
• After hydrofracturing one well (EX-1), its water-level tidal signature and barometric efficiencies became nearly identical to the other well (W-03).
• Aquifer testing confirmed connectivity along the fault-zone aquifer between the wells.

Conclusions:

• Hydrofracturing successfully induced new fractures and established connectivity between previously isolated wells.
• Water-level responses to barometric pressure and earth tides serve as effective indicators of fracture connectivity.
• The methodology offers a straightforward approach to assess hydrofracturing effectiveness and subsurface connectivity.