Hydraulic fracturing is a well stimulation process used to release oil, natural gas, geothermal energy, and even water from "tight" underground formations to maximize the extraction of these resources. Hydraulic fracturing is used by the oil and gas industry to fracture low permeability, resource-bearing subsurface rock to allow oil or natural gas to move more freely from the rock pores to production wells that bring the oil or gas to the surface.
During hydraulic fracturing, frack fluid, consisting primarily of water with chemical additives, is pumped into a geologic formation at pressures up to 15,000 psi. The high pressure of the fluid, which is designed to exceed the rock strength, opens or enlarges fractures that can extend several hundred feet away from the well. After the fractures are created, proppants in the fluid are pumped into the fractures to keep them from closing when the pumping pressure is released. After the fracturing is completed, the downhole pressure of the geologic formation causes the injected fracturing fluids to rise to the surface where it is typically stored in tanks or pits prior to disposal or recycling. Since the flowback fluid may contain numerous contaminants, proper handling/disposal of the flowback fluid is required.
Importance of USSI’s Fiber Optic Systems for Unconventional Energy Production
Currently, less than about 3% of 20,000+ frack jobs performed annually in the United States are monitored. This monitoring process, called microseismic monitoring, combines subsurface sensors with powerful data collection and analysis software to record the myriad of tiny microseisms (or microearthquakes) that occur as fluid is pumped into a well bore, splitting or fracturing the subsurface rock formation holding the natural gas or oil.
The individual locations of these microseismic events are then mapped to create an image of the fracture locations. As the name microseismic implies, these are small events, thus the need for the much higher detection sensitivity of USSI’s fiber optic geophones.
Most producers will readily admit that increased monitoring will lead to reduced environmental impact and improvements in efficiency, however, based upon today’s electronic sensor technology, it is simply unaffordable. The problem is that using today’s electronic sensor technology, the cost of a system to provide the monitoring is approximately $5M, which comparable to the cost of completing the well. This is cost prohibitive, especially at today’s low gas prices. And, this cost does not include the drilling of instrumentation wells for the sensor arrays, or their installation. USSI’s fiber optic sensor systems for microseismic monitoring are based upon proprietary fiber optic technology that is substantially less expensive. In full production, USSI’s microseismic systems will sell for approximately 10% of the cost of today’s electronic systems. USSI is in discussions with the companies responsible for over 75% of the frack jobs performed annually in the US. Most of these companies tell USSI that they will monitor 100% of their frack jobs if USSI can meet the 10% cost target.
As is usually the case with the introduction of a new technology, a few progressive companies are looking to become industry leaders in the responsible and efficient development of our country’s shale gas resources become the early adopters. Such is the case with FTS International (previously Frac Tech Services), a leading independent provider of well stimulation (hydrofracking) services for the oil and gas industry in the United States with a focus on environmentally friendly ways to do business - developing vital assets and promoting energy independence, while protecting natural resources. FTS International, one of this country’s largest multi-stage, unconventional completion services companies, intends to work with USSI to develop a custom fiber optic microseismic monitoring solution that will eventually enable FTSI to be the first to offer cost-effective monitoring of 100% of their frack jobs.
Increased monitoring will contribute in minimizing environmental concerns before and after the hydrofracking process.
Chemical contamination of subsurface aquifers can be caused by either fractures/fissures occurring outside of the desired fracture zone, or leakage along the well bore due to a faulty casing/cement job. Both of these adverse events can be detected via low cost, passive downhole fiber optic sensors. Once detected, remediation efforts to correct the problem can be implemented.
Gas migration refers to gas entry into the cemented annulus (area between metal casing strings) creating channels with the potential to provide a gas/fluid flow in the annulus. Migrating gas can effect water supplies, as well as potentially accumulate inside or next to structures such as residences, businesses and farming operations. This could create a risk of a fire or explosion. Gas migration may become a threat to the health, safety and welfare of the public. Properly cementing and casing a well is very important to prevent gas migration. In May of 2011 researchers at Duke University released a study that found high levels of leaked methane in well water collected near shale-gas drilling and hydrofracking sites. The Duke researchers said that the presence of methane likely was due to its escape from faulty drill casings (gas migration). This peer-reviewed study, published in the Proceedings of the National Academy of Sciences, was one of the first to conclude that hydraulic fracturing is polluting ground water. Interestingly, the Duke researchers found no evidence of contamination from chemical-laden fracking fluids, which are injected into gas wells to help break up shale deposits, or from “produced water,” wastewater that is extracted back out of the wells after the shale has been fractured.
USSI has developed a well bore leak detection system (patent pending) designed to detect leakage along the well bore surface casing. The system is based upon the USSI PipeSafe™ fiber optic leak detection system for natural gas pipelines.
Induced seismicity refers to earthquake activity that is the result of human activity. Numerous studies have indicated that induced seismicity can be caused by injecting fluid into the subsurface or by extracting fluids at a rate that causes subsidence and/or slippage along planes of weakness in the earth. Lawrence Berkeley National Laboratory is currently conducting extensive research into induced seismicity brought on by hydrofracking operations for both oil and gas extraction and enhanced geothermal activity, and believes that monitoring during the hydrofrackking process will allow more precise control thereby minimizing induced seismic events.