Underground imaging in real time by using white noise reflection processes: application to petroleum recovery including oil sands

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Repeated seismic shoots, often referred to as 4D seismic, are used to understand the in situ evolution of oil and gas recovery processes. For example, for thermal recovery processes for oil sands reservoirs such as Steam-Assisted Gravity Drainage (SAGD), repeated seismic shoots can be used to determine how the steam chamber grows within the reservoir. The uniformity of the steam chamber is directly related to the amount of oil produced and the efficiency of the process: the more uniform the steam chamber, the larger the amount of oil and lower the amount of greenhouse gases emitted to the atmosphere. Continuous monitoring, done by 4D seismic, of the steam chamber is required to view steam chamber evolution to maximize oil produced and minimize emissions. However, seismic data acquisition and interpretation requires extensive time for processing and its spatial resolution is of the order of 10 m. Thus, seismic methods have large uncertainties associated with estimates of the chamber size, shape and internal discontinuities in the reservoir such as shale layers and other flow barriers. Here, we propose to continue our development of white-noise reflection technology to image underground reservoirs and their heterogeneity at resolution of the order of meters or smaller in real time. White noise reflection technologies are low energy, can be analyzed quickly enabling real-time monitoring of oil extraction processes, and allow resolutions down to length scales not yet achieved by 4D seismic methods. To date, white noise reflection has been tested by using detailed thermal-acoustic reservoir simulation with application to the SAGD process and in the lab by using a large physical model apparatus. The results from simulations and lab testing reveal that the technology have the potential to image reservoirs at lower power levels and higher frequencies than seismic methods. Since the method uses orthogonally-coded signals, noise from recovery processes and the native reservoir environment do not interfere with monitoring. Funding is required to go to the next stage: testing in the field. A large oil services company has agreed to participate in testing of the technology in the field.