Laboratory Testing, Simulation and Imaging of Data from Fluid Flow Monitoring in Tight Reservoirs

There is today an urgent need to develop highly effective, cost-efficient and transparent solutions to characterize and monitor fluid injection and production fluid flow in Unconventional Oil and Gas (UOG) and tight reservoirs. This to boost the oil recovery, currently estimated at 5 – 8% of Original Oil In Place (OOIP), while satisfying the public and regulators that UOG operations are conducted safely and compliant with environmental laws. During reservoir stimulation, the injection points, the rate, and location of the generated fluid flow in the UOG reservoirs are extremely important factors. Today, away from the injection wells, producers cannot measure, spatially locate, or even detect the fluid flow in sub-surface formations after fracturing the formation because of today’s ineffective instruments. The micro-seismic fracture flow events are too small and too high frequency for detection. During a 2016 micro-seismic survey, funded by DOE, for Battelle and Core Energy in a Michigan reef, Paulsson, Inc. (PI) recorded data for four weeks using an array of twelve 3C Fiber Optic Seismic Vector Sensor (FOSVS) pods deployed into a horizontal well to a drilled depth of 6,000 ft. Analyzing the data, we detected more than 100,000 small, about M-5 to M-6, high-frequency micro- seismic events which were highly correlated temporally to the CO2 injection pressure. Such data has never been recorded before, and such a recording was only possible because of the extreme sensitivity of the FOSVS at the higher seismic frequencies, over 2,000 Hz, generated by the small fluid flow events. We will build a fracture flow test facility consisting of two back to back 24” OD round granite blocks that are precision ground. The interface between the two blocks will form an idealized fracture plane that will be used to inject water and CO2 through a drilled hole in the middle of the upper granite blocks. This fluid injection and fracture fluid flow will be monitored with an array of our FOSVS mounted on the outside of the granite blocks. These sensors are capable of recording micro- seismic events smaller than 1.0 μJ seismic events in the laboratory. This is less than a M-7 event. The purpose of this experiment will be to reproduce the long-duration high-frequency small-magnitude events we recorded during the 2016 micro-seismic field survey for Battelle. If we can verify in the laboratory the character of the microseismic events recorded in the field, we have taken a big step in understanding the subsurface fluid flow that can be used to optimize subsurface energy extraction processes. The data acquisition and processing technologies developed in this project will benefit the UOG, CCUS, Oil & Gas, Gas Storage and Geothermal (EGS) markets. The strength of fiber sensing is that the optical fiber transducer can translate very small micro- seismic events, smaller than M-7, into data that can be processed, correlated with operating parameters, and potentially utilized to train machine learning (ML) algorithms. In the UOG markets it is estimated that only 5 - 8% of the OOIP is recovered. By utilizing the sensors and data processing technologies developed we will be able to track fluid flow from the injection wells and the production of fluids such as oil and gas. This should significantly increase the recovery rates for both conventional EOR and UOG fields. In EGS market the efficiency of the heat extraction process, and potentially the thermal lifetime of the underlying resource will be much improved by higher resolution fluid flow monitoring.