Unconventional Resources
Injection and Tracking of Micro-seismic emitters to Optimize Unconventional Oil and Gas (UOG) Development Last Reviewed
August 2018

DE-FE0024360

Goal
The project goal is to develop fracture and fracture proppant mapping and monitoring technologies that will allow for both efficient and environmentally prudent development of UOG by developing and simultaneously deploying two novel seismic sensor technologies in an UOG well. The first technology, an Acoustic Micro Emitter (AME) can be mixed with proppant in small concentrations and injected into the hydraulic fractures concurrent with the conventional proppant to track the actual location of the proppant and compare these locations with the location of the actual fracturing. The second technology is an ultra-sensitive, large bandwidth, large aperture, Fiber-Opti Seismic Vector Sensor (FOSVS) array that can be deployed in both vertical and horizontal wells to map the actual rock fracturing process, the location of the proppant, and the location of the AME injected into the fractures. The FOSVS will monitor the injection process by recording and locating the microseismic events generated by the primary hydraulic fracturing process of the reservoir rock, the location of the proppant, and the size of the fractures by recording microseismic data emitted post injection by the AMEs mixed and injected together with the proppant.

Performers
Paulsson Inc., 16543 Arminta Street, Van Nuys, CA 91406-1745
Fluidion, 231 Rue St. Honore. 75001 Paris, France
Southwestern Energy, 515 W. Greens Road, Houston, TX 77067

Background
In the U.S., very large UOG resources are found in shale deposits. According to a 2009 estimate by the Energy Information Administration (EIA), the volume of technically recoverable gas from gas shale is 862 trillion cubic feet (TCF) — enough for 34 years of consumption at the 2009 level of 24 TCF/year. In 2012, EIA estimated that the U.S. possesses 33 billion barrels of technically recoverable shale oil. However, production of these shale gas and oil resources is often inefficient and often has a significant environmental impact due to the lack of detailed images of the reservoir and a poor understanding of the production processes. To lessen the environmental impact and improve the economy of producing the shale gas resources, one has to be able to map the natural fractures in greater detail, and monitor the induced hydraulic fracturing and injection of the proppant in the fractures at much greater resolution than what is possible today. Tracking of both the hydraulic fracturing and the location of the proppant will allow us to ascertain the effectivess of both the hydraulic fracturing and the injection of the proppant.

It has been shown that borehole seismology is technically able to map both natural and induced fractures in 3D, and monitor the process of inducing fractures using 3C borehole seismic data from both active and natural sources. It is thus established that if large volumes of high quality borehole seismic data can be recorded in vertical and horizontal boreholes drilled to and into shale gas and oil reservoirs, the data can be used to image and monitor the reservoirs. Such improved understanding can only be obtained by applying an array of advanced seismic mapping and monitoring technologies recording a full suite of high quality seismic data. This project will develop a multi reservoir attribute mapping and monitoring system to provide a new level of understanding of shale reservoirs that will enhance the production and make the shale gas and oil production processes environmentally prudent by improving production efficiency, and safer for the surrounding communities through better control. Simultaneously with recording seismic vector data the optical system will record Distributed Temperature Sensor data and Distributed Acoustic Sensor (DAS) data, further improving our understanding of the reservoirs and the dynamic UOG recovery process. In the future, other optical based sensors can be added to create a multisensory Optical Reservoir Characterization System.

Impact
High resolution imaging and monitoring of shale gas and oil reservoirs are critical to effectively produce and manage these reservoirs. In the past, borehole seismic imaging and monitoring have shown to have a great potential to provide the images and the monitoring information to manage these reservoirs. However, these techniques have in many ways fallen short; the amount of data has not been sufficient temporally and spatially, and the quality of the data has been poor.

Paulsson is building a borehole seismic system that overcomes the shortfalls of the current borehole seismic acquisition and processing technologies. The new borehole seismic system will allow deployment in both vertical and horizontal wells, which is not possible with commercial systems today without using expensive and fragile well tractors for the deployment. The new borehole seismic system will have a bandwidth from ~0 Hz to 6,000 Hz, which is much broader than what is provided by any existing commercial system. The new system will be approximately 100 times more sensitive than geophone based borehole seismic systems. The new optical sensor system will deploy sensors with an 80 dB rejection of out of plane seismic energy. The new system will allow for deployment in deeper wells, at higher pressures and temperatures than what is possible today. The new FOSVS sensor has been tested at 320°C (608°F). In combination, the new fiber optic based seismic sensor will record far superior data, which will allow for the generation of superior images, and superior detection and location of micro-seismic events.

The development of AMEs, together with the means to record data from the AMEs using the FOSVS system, will for the first time provide operators of UOG resources with a proppant tracking technology that potentially will allow the operators to calibrate and tune the hydro-fracturing and proppant injection processes.    

Accomplishments (most recent listed first)

  • Paulsson is in the process to commercially introduce the FOSVS to the oil and mining industries. There is significant interest in the promise of multi-sensor optical systems.
  • Paulsson presented at the Mastering the Subsurface Through Technology Innovation, Partnership & Collaboration held in Pittsburgh, PA August 13-16, 2018. Paulsson presented the borehole seismic advances, current technology, and reviewed the potential of FOSVS technologies.
  • Paulsson has further improved the performance of the FOSVS making them even more sensitive at low frequencies.
  • Paulsson has developed its own Fiber Bragg Grating (FBG) system that will allow them to write gratings faster with lower cost. The FBG writing system will also allow Paulsson to write experimental FBG.
  • Fludion completed Hydrodynamic simulation of the timing circuit, performed under representative pressure and temperature conditions (Poiseuille flow simulation in rectangular channel geometry). Three timing circuit designs were cleanroom-manufactured out of silicon and glass, corresponding to 5min, 30min, and 1hr timing delays. Tests using specific slick-water formulations are in preparation and will be underway early FY19.
  • Fluidion has performed an all-silicon manufacturing of the AME, using a recently-developed eutectic bonding process for sealing the devices. This manufacturing technique offers better machining capabilities for complex MEMS and microfluidic devices, because the etching of silicon is much better controlled than that of glass. They have also developed a new brazing process for sealing the devices that requires the use of a pick- and-place machine.
  • Paulsson complied and presented at the Oil and Gas Peer Review, held at the NETL Pittsburgh Site on December 4-5, 2017. Paulsson presented project status and current TRL level at the Peer Review. Peer Review members were from Industry and Acedemia.
  • Award was modified to included additional in scope funds to add additional testing for the AME and the Paulsson project developed the FOSVS tool. Paulsson successfully designed, prototyped, and laboratory tested the fiber optic seismic sensors at different frequencies and at different temperatures. They have specified, selected, and purchased the sensor fiber. They have also specified, selected, and purchased the FBG’s for the sensors. Compared the fiber optic seismic sensors with state of the art accelerometers and state of the art geophones. In each case, our fiber optic seismic sensors record significantly better data than the legacy geophone sensors.
  • Paulsson completed the manufacturing of 300 sensors that will be used in the 100 level 3C array. The sensors manufacturing process is being perfected to improve the sensitivity of the sensors.
  • Paulsson successfully tested and tuned the interferometric interrogator that will be used for the fiber optic seismic system. Paulsson has upgraded the interrogator with a new set of Erbium Doped Fiber Amplifiers. Paulsson has completed the design of the interrogator and are in the process of manufacturing a prototype unit that can operate 300 seismic channels using fiber optic sensors.
  • Paulsson and Fluidion successfully completed a laboratory bench-scale test of the AME prototype in conjunction with the Paulsson optical fiber tool and demonstrated the compatibility of the two technologies. The AME signal was clearly observed. The test compared the measurement of the Paulsson tool, a standard geophone, and high-end accelerometer. Only the Paulsson tool was able to detect the AME signal.
  • Fluidion manufactured an additional AME prototype for additional testing and characterization, as well as planned a small-scale field test to assess the energy output of the AMEs and to study the generated waveforms from different sized AMEs as actuated in an acoustic medium.
  • Two sets of complete sensor pods are being prepared for high-temperature, high-pressure testing in a new pressure test facility. Paulsson has successfully tested and tuned the interferometric interrogator that will be used for the fiber optic seismic system for both the small-scale field test and the full deployment for testing the systems during a hydraulic fracturing service. Paulsson has also completed the manufacturing of 110 sensor-pods to be used during field operations. To date, Paulsson has upgraded their field processing capabilities and are now able to record and process micro seismic data in real time.
  • Paulsson designed and built a 10,000 psi pressure vessel to be used to test AMEs. This pressure vessel was used to perform a laboratory test in a 50 gallon test vessel using new and high energy AMEs. Outstanding data were recorded. This test will be followed up with a second pool test in December 2016.
  • Paulsson and Fluidion performed a second joint test of the Fiber Optic Seismic Sensors (FOSS) and the AMEs in September 2016. This test was conducted in a 30 ft long pool. The AMEs were placed in a pressure vessel near one side of the pool and the FOSS receiver was placed in the pool 20 ft from the vessels with the AMEs. Outstanding data were recorded.
  • Paulsson submitted the second Go-No Go report to the U.S. Department of Energy (DOE) on March 31, 2016, and received approval from NETL to proceed based on the technical progress they have made on the design and the prototyping of the fiber optic vector sensor pods. The recipient provided the DOE TPO with a technical briefing.
  • The design of the sensor pressure housing capable of surviving up to 20,000 psi at a temperature of 392°F was completed.
  • Inconel X-750 was selected as the appropriate material for the sensor pods and Inconel 825 as the appropriate material for the fiber tube because it has the ability to withstand long term operation in oil and gas wells. Also completed the design of the spool that will be used during deployment of their tool.
  • Paulsson successfully performed an extensive set of measurements on the Phase 1 fiber optic vector sensors. The sensors perform as expected with a sensitivity in excess of 360 Radians/g. The sensors have also proved to be able record data from 0.03 Hz to 6,000 Hz. Paulsson compared the data from the fiber optic seismic sensors geophones and accelerometer. In a side by side laboratory test of the fiber optic seismic sensors with geophones and accelerometers using the AMEs as the seismic source, the fiber optic seismic sensor produced data with a S/N ratio of 250, the piezo electric accelerometers produced data with a S/N ratio of five (5) while the geophones did not record any detectable data. In tests of the sensitivity of the fiber optic sensors, Paulsson demonstrated that impulsive source at 2.5 micro Joules (µJ) could be detected with a bandwidth in excess of 1,000 Hz.
  • As part of a separate project, Paulsson completed a field test of a 16 level optical system similar to that to be used in award number FE0024360, proving that their optical seismic sensors are able to record seismic data in the field. Lessons learned from this test will be used in developing the field study to be conducted in this award using Fluidion’s AMEs.
  • Paulsson completed steps to tune the fiber optic interferometric interrogator to maximize the signal to noise ratio of the data recorded with our sensors.
  • Paulsson completed all of the laboratory tests defined in Task 6, excluding testing the system at elevated pressure. The sensors have shown to meet all project defined specifications; 100 times as sensitive as geophones, operate at 500°F, can record broad band data from 0.03–6,000 Hz, and with a vector fidelity that exceed project defined specifications.
  • Paulsson completed testing of the sensors with the existing interrogator system and will use the test data to upgrade and fine tune the design of the interrogator that will serve the 100 level 3C system.
  • Paulsson selected the material for the sensors and completed the sensor machining in their in-house machine shop and at a specialty EDM machine shop. Paulsson completed the purchase of the sensor fiber for the sensors and selected the FBG design to be written into the sensor fiber. Paulsson completed material purchase for the FBG arrays for 110 3C pods.
  • Paulsson completed a literature review regarding fracturing fluid composition and additives, and concluded that the current trend in shale fracturing is the use of slick water, with viscosities similar to that of normal water (~1cP). Researchers obtained samples of actual sand and resin coated sand proppant particles from field locations in Texas. They made a field trip to an actual fracking site in Arkansas, where they were able to witness a complete fracturing job. This will provide the additional constraints (mechanical, pumping conditions etc.) that will be required to draft the final AME specifications and to plan deployment in actual wells.
  • Paulsson completed the design and manufacturing of the high- pressure, high-temperature (HPHT) microscopy bench rated and pressure tested to 10,000 psi, capable of performing direct microscopic observation using an existing LEICA inverted metallurgy microscopy setup. The bench used high strength steel for the housing, a sapphire window sealed with Viton O-ring for the optical port, and bronze cap. All the materials are qualified for continuous operation at pressure at temperatures to 170°C, and will withstand occasional operation to 200°C. These temperature and pressure conditions are beyond what is typically found in hydraulic fracturing wells.
  • Paulsson submitted the First Go-No Go report to DOE on February 28, 2015, and received approval from NETL to proceed based on the technical progress they have made on the design of the fiber optic vector sensors. The recipient provided the DOE TPO with a technical briefing.
  • Successfully completed a laboratory bench scale test of the prototype AME in conjunction with the Paulsson optical fiber tool and demonstrated compatibility of the two technologies. The AME signal was clearly observed, with high signal-to-noise ratio on the Paulsson tool. The test compared the measurement of the Paulsson tool, a standard geophone, and high-end accelerometer. Only the Paulsson tool was able to detect the AME signal at a useful signal-to-noise ratio. The geophone did not detect the signal at all.
  • Completed the design and manufacturing of a HPHT microscopy bench rated and pressure tested to 10,000 pounds per square inch (psi).
  • Designed and manufactured the initial prototype batch of test AME.
  • Paulsson designed and fabricated the proppant flow fixture from polymethyl methacrylate using laser cutting as well as 3D laser engraving. An actual fracture geometry was used and could be imprinted onto the fracture walls to simulate a real environment. A review was performed of all proppant transport and fracture geometry literature to date, and previous experiments were analyzed and conditions adapted to the current setup. Transparent glass microspheres were used to allow the visualization of proppant, in conjunction with both opaque and photo luminescent mockup AMEs. Researchers used widths from 1 mm to 12 mm, which are representative of actual fracture geometries recorded in the field. They also included tapered joints to allow for variable width fractures (6 mm to 2 mm and 3 mm to 1 mm). Different geometries of AME (cylindrical vs. rectangular, different sizes) were attempted, and the time-dependent distribution of proppant and AMEs was recorded using photos and videos. The experiments using this setup are ongoing, and data are being collected. Publication of these results is planned for later in the year.
  • Completed the sensor design for operation up to and exceeding 392°F, with a maximum pressure of 20,000 psi and capable of withstanding fluids found in wells drilled in shale oil and gas fields.
  • Completed the design for the 1,000 channel interrogator capable of maintaining the data sensitivity of a minimum of 360 radians/g and a noise floor less than 50 ɳg/√Hz.
  • Completed the design of the sensor pressure pods capable of surviving up to 20,000 psi at a temperature of 392°F.
  • Completed the selection for the fibers and the fiber coatings to be used in the fiber optic seismic vector sensors.
  • Selected the material and completed the design for the pressure housing for the fiber optic seismic sensors. The design will utilize Inconel 750 for all the pressure pod components. The structural resonance is modeled to approximately 2,000 Hz.
  • Completed the design of the ¼” Inconel fiber tube with fiber that provides the required response when used as a DAS. Testing of several fibers was completed resulting in the selection of one with the appropriate Rayleigh scattering response for use in the DAS field deployment. Also completed test of several fibers for frequency response and selected an appropriate fiber with the best combination of properties.

Current Status (August 2018)
The Paulsson project team are investigating a new data telemetry approach to further lower the noise in the data which will result in an improved Signal-to-Noise (S/N) ratio. The team is also in the process of completing the manufacturing of the sensor pod housings. The team is planning two field deployments during. First, a small scale field test at the Devine Testing Facility to assess the energy output of the AMEs and to study the generated waveforms from different AMEs subsurface and to test the Fiber Optic Sensor System’s (FOSS) ability to locate the AME subsurface. Second, deploy AME’s along with proppant during a hydraulic fracturing operation and measure their signal using the multiple level array of the FOSS from an adjacent wellbore. Paulsson has requested a No Cost Extension for one year. The project is proposed to be extended to a new award end date of September 30, 2019.

Project Start: October 1, 2014
Project End: September 30, 2018
Requested Project End: September 30, 2019

DOE Contribution: $4,378,000
Performer Contribution: $3,116,463

Contact Information:
NETL – William Fincham (william.fincham@netl.doe.gov or 304-285-4268)
Paulsson – Bjorn Paulsson (bjorn.paulsson@paulsson.com or 310-780-2219)

Additional Information:

Injection and Tracking of Micro Seismic Emitters to Optimize UOG Development (Aug 2017)
Presented by Bjorn Paulsson, Paulsson Inc., 2017 Carbon Storage and Oil and Natural Gas Technologies Review Meeting, Pittsburgh, PA

Injection and Tracking of Micro Seismic Emitters to Optimize UOG Development (Aug 2016)
Presented by Bjorn Paulsson, Paulsson Inc., 2016 Carbon Storage and Oil and Natural Gas Technologies Review Meeting, Pittsburgh, PA