By Iain Weir-Jones
Fracking has become a major source of national and international economic growth as companies discover the value of tapping large reserves of oil and gas from shale formations.
But in doing so, they must be aware of several negative aspects of fracking, including induced seismicity and regulatory restriction that are being introduced in many jurisdictions to protect structures, people and the environment.
A case in point is Alberta, where fracking operations are suspected of causing a significant number of induced earthquakes in several gas and oil producing regions. In the town of Fox Creek alone, there have been more than 160 earthquakes since 2013 when fracking started, including a 4.4 earthquake on June 13, 2015.
The regulatory fallout in Alberta has been swift.
Since February 2015, the Alberta Energy Regulator (AER) requires operators in the Fox Creek region and at other locations in the province to follow the “AER Traffic Light System – Duvernay Zone, Fox Creek,” which stipulates that if an earthquake greater than local magnitude 4.0 occurs, operators must inform AER and shut down operations. For events greater than 2.0ML, operators must inform AER and initiate a response plan. For less than 2.0ML, no action is required.
Fortunately, innovative technologies in seismic monitoring have been developed to help mitigate the impact of induced seismicity and new and future regulations.
One technology is Passive Micro-Seismic Monitoring (PMM), which can provide enough reliable data to make decisions about the probability of induced fractures affecting aquifers, other subsurface resources, or inducing low level seismicity.
During the past forty years, a dramatic evolution in the technology has meant that engineers can now monitor geo-mechanical phenomena at depths of greater than 10,000 feet. In the oil and gas sector, production and fracking operations can be monitored in near real-time so precisely that they can shut down immediately if a safety or operational situation arises.
A PMM installation can help monitor fracture growth, increase production, and avoid induced seismicity events with the potential to put lives at risk and cause substantial damage to equipment and nearby structures. A PMM gives geophysicists the ability to do real-time interpretations with fracture mapping, and allow hydraulic-fracture treatment stages to be modified on the fly for optimization.
The PMM gives operators the ability to detect earthquakes at their current location, which enables them to conform to regulations put in place by governments.
Without question, PMM is a key and essential tool for hydraulic fracturing. It assists in complying with regulations, and avoids and prevents induced seismicity and other environmental hazards. The downside, however, is that most existing PMM systems are extremely expensive, often ranging from $250,000 to $400,000 due to the labor and equipment involved. At a time when oil prices are nearing record lows, these costs can be prohibitive for operators
A new generation of Induced Seismicity Monitoring Systems has recently been introduced that offers a low-cost alternative to traditional PMMs, plus various other benefits, which have created a paradigm shift for induced seismicity monitoring.
Previously, seismologists often assumed each injection facility or region needed a network of observatory grade sensors capable of detecting and locating events to magnitudes less than 0, which is a very expensive proposition. The new systems have been developed specifically for induced seismicity monitoring, working within the relevant ranges of magnitudes pertinent for frac monitoring and regulatory compliance: 0.5 magnitude and larger.
For regulatory compliance, a PMM installation does not have to be overly complex and can consist of as few as 1 or 3 surface installations in the vicinity of a well. A single station can provide seismic magnitudes, event distance from the well and seismicity rates which can be used to modify injection activities. Three or more stations can add seismic location to reporting and also reduce the potential for false alarms.
The monthly cost of the new frac monitoring services can start at approximately $3,000 (USD), which includes the equipment, monitoring and near real time reporting of all relevant seismic activity. This is a fraction of the cost of current PPMs and in addition, installation time and costs are vastly reduced. Setup can be usually be completed in less than one hour, and no special equipment, material, or tools are required. The new system is capable of reporting and alerting any seismic activity back to the operator within seconds using its onboard processing capabilities, sending either email or text alerts to an operator and to a preset list of employees or relevant third parties.
Perhaps of more significance, these Next-Gen systems give operators the tools to remain compliant with all current and future regulations, while providing them with information to remediate their operations if necessary or required.
Likewise, they can give regulators, interested third parties and the public greater piece of mind that frac operations can work within acceptable norms and regulatory requirements.
Iain Weir-Jones is president/founder of Weir-Jones Engineering Consultants of Vancouver.