Sub Rosa Monitoring LLC, an Arizona based company, has developed a flagship methodology that can provide quantitative data for time-lapse characterization and monitoring of subsurface fluid flow. Depending on the level of implementation, the technology can produce 2D or 3D dynamic images of injected fluids by measuring the spatial variation of the associated electrical field.
The monitoring technology relies on a special application of quasi-direct-current methods to observe changes in subsurface electrical properties during the injection and subsequent movement of water, steam, oil, carbon dioxide, surfactant, or many other sub-surface fluids. It is a non-intrusive measurement and effectively monitors spatial and temporal evolution of fluid migration in the subsurface. In short, it will show in real time where the fluid is moving.
The preceding tasks are accomplished by obtaining a background electrical signature of the subsurface and then record and observe the changes in that signature during fluid injection. Similar technologies have been very successful in the near surface environment. Flow Vector Inc. has researched and developed a system design to acquire the electrical signature at depth and proprietary analytical processing steps of the recorded quantitative data that allow real time high resolution vectoring of the fluid flow regime in the subsurface environment.
This technology has profound applications to the oil and gas, geothermal, in-situ mining, CO2 sequestration, and storm water injections. Currently enhanced oil recovery (EOR) and hydraulic fracturing is the primary target market. Whereas passive seismics and other technologies have been used for monitoring the development of microfracturing during water floods or hydrofracking, Sub Rosa actually detects where the fluid goes. This advantage makes Sub Rosa an attractive and cost effective option for monitoring subsurface fluid movement in oilfield settings. Furthermore, Sub Rosa uses existing metallic well casings as sensors and does not require extensive modifications to surface infrastructure. The methodology has been successfully demonstrated at Teapot Dome at the Rocky Mountain Oilfield Testing Center (RMOTC) near Casper, Wyoming and has been deployed successfully in other non-oil related environments.
System field setup consists of temporarily connecting sensor cables to well heads/steel casings and running them back to a central data acquisition trailer. Individual steel casings and electrodes will then be electrically energized and the resultant electric field will be monitored at all other available connected steel casings and surface electrodes (approximately 30 combined) in the monitored array. Transmission of the electrical current will progressively rotate through each electrode over time. Once a background data set has been obtained the injection fluid is electrically energized (through casing contact) and injection commences. Data acquisition is continuous. Once the injection conditions have stabilized and subsurface flow regimes have reached their operational mode, the injection is turned off and the field returns to equilibrium, again with continuous data acquisition. The system would then be dismantled and removed from the site. The system will be deployed in the field approximately one week prior to the injection, during injection, and one week after the injection. Processing and modeling of the quantitative data is then completed utilizing Sub Rosa proprietary analysis.