Induced Seismicity

Reducing the Potential for Induced Seismicity During Hydraulic Fracturing – With N2 and CO2 Based Foamed Fluids

A Ferus and Itasca – Image Joint Project – September 2016

Causes of Induced Seismicity During Hydraulic Fracturing (HF)

• Seismicity has been linked to:

• High injection rates and pressures

• High volume water fracs (incompressible fluid)

• Slickwater tends to migrate many thousands of meters from the well, intersecting with faults, lubricating the fault to slip

Ferus’ Hypothesis on Fracturing Fluids

• Fracture fluid properties have an effect on the amount of seismic events and the magnitude of the events

• Foamed fluids are viscous, have inherently superior leakoff control, and if encountering a fault, will not enter the fault as readily as low viscosity fluids;

• Foamed fluids under high shear (which may be encountered at the opening of a fault) will leakoff the gas first, the gas being compressible will enter the fault but not force it open

• Foamed fluids create useful fracture width and tend to not leakoff down fissures but stay close to the created fracture

• The compressible nature makes gases less likely to induce seismicity

Study Objectives

• Geomechanical investigation of the impact of hydraulic fracturing fluid viscosity on fault activation

• Modeling work conducted under the supervision of Mr. Shawn Maxwell of Itasca-Image

• Comparison of the fracture dimensions and seismicity rates between a viscous and a non-viscous fracture fluid

Study Results – Key Messages

• Fracture fluid system makes a difference – and may be used to reduce the risk of seismicity

• Fluid viscosity is a key factor – affects the amount as well as the magnitude of seismic events

• Viscous fluid does not readily enter the fault system; therefore does not lubricate or cause as much fault slippage

• NOTE: For details of the Study – Please ask for the Ferus White Paper ‘An Investigation of the Effects of Fracture Fluid Design on Induced Seismicity in a Gas Shale’.

Aperture and proppant evolution Slickwater with fault

Aperture

Proppant

Aperture and proppant evolution 70 Quality Foam with fault

Aperture

Proppant