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Detection and localization of seafloor hydrocarbon and related fluid seeps using Ocean Acoustic Waveguide Remote Sensing ( OAWRS)

IP.com Disclosure Number: IPCOM000218078D
Publication Date: 2012-May-18
Document File: 3 page(s) / 73K

Publishing Venue

The IP.com Prior Art Database

Abstract

In the oil and gas industry, modeling of the subsurface is typically utilized for visualization and to assist with analyzing the subsurface volume for potential locations for hydrocarbon resources. Accordingly, various methods exist for estimating the geophysical properties of the subsurface volume (e.g., information in the model domain) by analyzing the recorded measurements from receivers (e.g., information in the data domain) provided that these measured data travel from a source, then penetrate the subsurface volume represented by a subsurface model in model domain, and eventually arrive at the receivers. The measured data carries some information of the geophysical properties that may be utilized to generate the subsurface model.

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Detection and localization of seafloor hydrocarbon and related fluid seeps using Ocean Acoustic Waveguide Remote Sensing (OAWRS)

In the oil and gas industry, modeling of the subsurface is typically utilized for visualization and to assist with analyzing the subsurface volume for potential locations for hydrocarbon resources.  Accordingly, various methods exist for estimating the geophysical properties of the subsurface volume (e.g., information in the model domain) by analyzing the recorded measurements from receivers (e.g., information in the data domain) provided that these measured data travel from a source, then penetrate the subsurface volume represented by a subsurface model in model domain, and eventually arrive at the receivers.  The measured data carries some information of the geophysical properties that may be utilized to generate the subsurface model.

However, in certain measurements in marine or artic environments, other objects may introduce interference with the measured data.  For example, a survey may include a source that generates a signal, which is transmitted through the subsurface, and receivers that are positioned to detect the reflected signals.  As the signal travels through the body of water, it may have various sources of interference that disrupt the signal.  For example, schools of fish, whales, submarines, nets or other objects within the body of water may interfere with the measurements and introduce noise into the survey data.  These surveys may include seismic surveys, electromagnetic surveys or others data types. 

To address such interference, ocean acoustic waveguide remote sensing (OAWRS) technology has been developed and used to rapidly detect schools of fish and other objects in the body of water at distances of hundreds to thousands of kilometers.  An acoustic waveguide can be formed in a layer with sufficient impedance differences from its surrounding media due to the coupling of waves reflected at the boundaries.  In the ocean environment, the water surface, water bottom, and any kind of sound speed change due to temperature, pressure, or salinity difference naturally provide waveguides. Waveguides can propagate acoustic energy within the layer for long distances with small attenuation. In comparison, seismic p-wave amplitudes decrease rapidly because of spherical divergence (and attenuation). Thus, ocean waveguides can be used to scan a large water volume. OAWRS was developed by academia and has been successfully utilized to monitor fish schools (Makris et al. 2006) and oceanic ridges (Makris et al. 1995) in oceanographic research.

Beneficially, this (OAWRS) technology may be utilized in a variety of other processes.  For instance, this method can be adapted to detect and map hydrocarbon seafloor seeps over wide areas, from shallow to deep ocean environments.  Similar to fish schools, the seep-caused impedance changes relative to the surrounding water body could possibly be captured on the...