|Evaluation of Deep Subsurface Resistivity Imaging for Hydrofracture Monitoring
||Last Reviewed 12/23/2013
The goal of this project is to quantify how well an in-situ measurement of bulk electrical resistivity using the new method of Depth to Surface Electromagnetic (DSEM) imaging can be related to the changes in rock properties and fluid propagation that occur as a result of hydraulic fracturing.
GroundMetrics, Inc., San Diego, CA, 92123
Global Microseismic Services, Inc. (GMS)
Berkeley Geophysics Associates, Ltd.
Mountainview Energy, Ltd.
Approximately 45 percent of the world’s recoverable natural gas reserves are classified as unconventional. Worldwide, the share of unconventional gas production is projected to increase from 14 percent today to 32 percent. Increasing production from new, tight shale resources is projected to result in the U.S. overtaking Saudi Arabia as the world’s largest producer of liquid fuels (oil, natural gas, and biofuels) as early as 20131.
Hydraulic fracturing (fracking) has enabled commercial production from unconventional formations. However, fracking is more expensive than the conventional methods used to produce gas and oil, and fracked wells exhibit a much faster decline in production than conventional wells. Furthermore, there are environmental concerns with the amount of water required, pollution of groundwater reservoirs, triggering of earthquakes, and release of methane into the atmosphere. A key concern of the general public is hydrofracturing out of the formation and into the groundwater table.
Unconventional wells exhibit highly variable production in a given area, and often the majority of gas or oil produced comes from only a few of the fracturing stages, resulting in more extensive fracturing operations than are really needed and an excess proppant being pumped into the formation. These inefficiencies indicate that the eventual destination of the injected fluids used in reservoir stimulation is poorly understood.
1BP Energy Outlook 2030 http://www.bp.com/genericarticle.do?categoryId=2012968&contentId=7083149, accessed 1/27/2013.
Seismic methods are used to locate hypocenters and, via the tomographic fracture image method, produce images of entire fracture networks. However, the underlying data represent the fracture of the host rock. In contrast, if successful, the proposed DSEM method will image the presence of hydrofracturing fluid in the new pore spaces and quantify the resulting increase in porosity. We anticipate the following project impacts and benefits:
- Reduced cost and use of fracture fluid by reducing the number of fracture stages.
- Improved recovery and reduced environmental impact via improved mapping of fracture propagation.
- Reduced cost from replacing high cost aspects of a microseismic seismic survey withelectromagnetic elements. Extension of microseismic methods to formations where they currently are problematic and provide inadequate information.
- Developing and demonstrating ways to monitor hydrofrac height growth.
Accomplishments (most recent listed first)
- An approach has been defined for the DSEM signal modeling.
- Fracture images have been provided by GMS.
- A list of requirements has been drawn up for central monitoring of the performance of all data recording units.
Current Status (December 2013)
Researchers will complete DSEM modeling of hydrofracture signals, develop and test a protocol for monitoring an array of recording systems, complete the equipment build, and finalize the survey design.
Project Start: October 1, 2013
Project End: September 30, 2015
DOE Contribution: $1,870,255
Performer Contribution: $583,333
NETL – Chandra Nautiyal (firstname.lastname@example.org or 281-494-2488)
GroundMetrics – Dr. Andrew Hibbs (email@example.com or 858-381-4146)
Quarterly Research Progress Report [PDF-794KB] October - December, 2013