Laboratory Testing, Simulation, and Imaging of Fluid-Flow Generated Micro Seismic Data in Geothermal Reservoirs

The US Geothermal resources are large, sustainable and green, but are difficult to develop partly due to a lack of robust, high temperature and accurate borehole tools that can be used for real-time reservoir imaging and monitoring. To improve Geothermal production, we need to develop efficient, robust, cost-effective borehole seismic, acoustic, pressure, temperature and strain acquisition, processing, and real-time analysis technologies to characterize and monitor injection and production of fluids into and from all Geothermal reservoirs.General statement of how this problem or situation is being addressed: During reservoir stimulation, the rate, the location, and the vector of the injected fluids into and from the Geothermal reservoirs are critical factors. Today, away from the injection and production wells, operators cannot detect or spatially locate the fluid flow in the sub-surface formations due to the low sensitivity, the low frequency, and poor vector fidelity of available instruments. The micro-seismic events from fluid-flow are too small and too high frequency for today’s commercial sensor technologies and no sensor combination systems exist. We are proposing to design, build and deploy an all optical multi sensor all-optical array of borehole sensors.What is to be done in Phase I: We will design and build a large aperture all-optical, >300°C capable, multi-instrument array by combining µJ and 10 kHz capable 3C Fiber Optic Seismic Vector Sensors (FOSVS) with large aperture Enhanced, +15dB, Distributed Acoustic Sensors (EDAS) with 3ft spatial sampling along the entire well and optical pressure, temperature and strain sensor arrays to record the conditions along the well. We will build a set of instruments suitable to be simultaneously deployed on our patented borehole deployment system. The deployment system, includes clamping, is built around a 1.660”OD, high strength drillpipe rather than a wireline. This allows the optical instruments to be deployed in both vertical and horizontal wells. We will build the instruments at our facility and test at high temperature and elevated pressures and record data from flowing fluids through a pipe packed with sand placed next to our sensors. Combining a number of FOSVS point sensors with a large number of a full well aperture EDAS array will provide for a unique seismic antenna. We will combine FOSVS and EDAS with pressure, temperature, strain sensors and our 1,600 Hz near-surface source. The results from the laboratory and field experiments will include an assessment of the tested seismic sensors to record small fluid flow micro seismic events in a well environment. This database will help us understand how monitoring fluid-flow with micro seismic can be used to optimize energy extraction from high-temperature geothermal reservoirs. LANL will provide guidance translating the recorded data into action.Commercial Applications and Other Benefits: The US Geothermal resources has several major advantages since it is a large domestic, widespread, and an ever-present baseload but it has been very slow to be commercialized. The development of suitable high-temperature high-fidelity instruments to characterize and monitor the subsurface will greatly facilitate the commercial development of Geothermal resources. The combined sensor technologies and the data from this project will have a game-changing impact on the development of our Geothermal resources. Fiber sensing data translate different optical scattering effects into seismic, acoustic, pressure, temperature, and static strains. Data that can be processed, correlated with operating parameters, and utilized to train Machine Learning (ML) algorithms further increasing the value. All Underground Energy Operations will be improved by high-resolution fluid-flow monitoring including Carbon Storage, Underground Gas Storage of both Methane and Green Hydrogen. It will also provide for more efficient, more environmentally compliant oil and gas production.