|Advanced Hydrate Reservoir Modeling Using Rock Physics Techniques
||Last Reviewed 1/7/2015
The primary goal of this research is to develop analytical techniques capable of quantitatively evaluating the nature of methane hydrate reservoir systems through modeling of their acoustic response using techniques that integrate rock physics theory, amplitude analysis, and spectral decomposition.
Fugro GeoConsulting, Inc., Houston TX
Past efforts under the DOE-supported Gulf of Mexico Joint Industry project included the selection of well locations utilizing prospectivity analysis based primarily on a petroleum systems approach for gas hydrate using 3-D exploration seismic data and derivative analyses that produced predicted gas hydrate saturation volumes. Logging–while-drilling at those locations confirmed the presence of high saturation gas hydrate reservoirs at two boreholes in Green Canyon Block 955 (GC955) and two boreholes in Walker Ridge Block 313 (WR313) in the Gulf of Mexico. The success of the four wells was a significant achievement and legitimized the conceptual approach taken to prospect for potential producible methane hydrate reservoirs in deepwater that could be exploited with modifications to present-day technology.
The success of future hydrate research wells and, eventually, resource exploration wells, will depend on the continued evolution of the techniques employed to select successful drilling locations. It is anticipated that future prospecting for methane hydrate deposits will be driven by their potential for exploitation as an energy resource. Geophysical prospecting techniques will need to be developed to both identify potential gas hydrate accumulations and better delineate and characterize these potentially complex systems and reservoirs.
This research effort will focus on developing and refining techniques that integrate rock physics modeling, amplitude analysis, and spectral decomposition. The expected outcome of the research efforts will be an enhanced ability to quantitatively evaluate and prioritize potential gas hydrate accumulations that may be selected as exploration drilling targets based on 3-D seismic data. Potential enhancements that are expected to result from research efforts include:
- More reliable identification and delineation of seismic data that illustrates the existence of gas hydrate accumulations
- Determination of class type of gas hydrate reservoirs
- Delineation of interfaces between gas hydrates and free gas across the prospect area
- Determination of hydrate concentration
- Determination of hydrate volume
- Determination of subjacent free gas concentration
- Determination of subjacent free gas volumes
Enhanced prospecting techniques for detecting and characterizing hydrate occurrences using seismic data will help reduce the substantial costs and risks and increase the likelihood of success of hydrate-focused deepwater drilling programs. These techniques will be important for initial research-based hydrate drilling activities, but may also eventually play a critical role in drilling programs seeking to exploit hydrates as an energy resource. Reliable selection and prioritization of gas hydrate drilling targets could have the following benefits: reduced costs incurred for drilling “dry” wells, increased likelihood of intersecting economically recoverable gas reserves, reduced exploration cost per volume of recoverable gas reserves, and enhancement of support for investment in future exploitation of gas hydrates as an energy resource.
- Acquired the petrophysical and inversion software required for the project.
- Began modeling mixtures of methane and thermogenic gas hydrate signatures against flux and geothermal gradients and depositional architecture.
- Completed an initial investigation of available well log data for Green Canyon 955 and Walker Ridge 313 sites.
- Selected the rock physics model to be used in the project.
- Developed the geostatistical/inversion analytical routines to be used in the project.
- Completed review of related scientific/industry research efforts.
Current Status (January 2015)
Activities under the project have been delayed due to a lack of access to seismic data (for target sites in the WR313 and GC 955 lease blocks) of sufficient quality for project purposes. The data that have been acquired were limited to a single seismic line extracted from a 3-D volume for each location and, unfortunately, neither line intersected the areas of highest interest in these locations (as identified by drilling activities under DOE-Chevron JIP project in 2009). Efforts going forward will continue to focus on access to a more workable data set as well as continued development of analytical techniques and protocols to distinguish class-type hydrate reservoirs.
Project Start: October 1, 2012
Project End: September 30, 2015
Project Cost Information:
Planned Total Funding: $213,444
DOE Contribution: $170,755
Cost Share Contribution: $42,689
NETL – Richard Baker (Richard.Baker@netl.doe.gov or 304-285-4714)
Fugro GeoConsulting Inc. – Dan McConnell (DMcConnell@fugro.com)
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