Oil & Natural Gas Projects
Exploration and Production Technologies
Offshore Oil Field Characterization with EM Methods
This project was funded through DOE's Natural Gas and Oil Technology Partnership
Program. The Partnership Program establishes alliances that combine the resources
and experience of the nation's petroleum industry with the capabilities of the
national laboratories to expedite research, development, and demonstration of
advanced technologies for improved natural gas and oil recovery.
The goal is to develop a high-temperature acoustic telemetry tool for the geothermal
industry, and construct a low-temperature version of the geothermal tool capable
of operating at raw baud rates up to 100.
Sandia National Laboratories
Building on SNL's 3D electromagnetic (EM) modeling software, a matrix-free finite
difference solution is now available for the marine magnetotelluric (MT) problem.
A series of model studies was conducted that computed the synthetic MT response
of the Gemini Salt Structure, whose spatial extent was inferred from 3D seismic
data provided by Texaco.
The key issue is to assess the ability of the MT method in characterizing the
base of salt. Testing of the finite element (FE) code showed favorable agreement
between FE solutions and those derived from analytic formulae for simple problems.
Preliminary results emphasize the continued need for close collaboration between
instrumentation development, data analysis, and numerical modeling efforts.
To address the issue of bathymetric effects on seafloor MT response, a 2D finite
element code was developed, also utilizing the matrix-free paradigm for enhanced
This new 3D forward engine with its unstructured mesh and mathematically rigorous
foundation can immediately address questions of target resolution, the role
of bathymetry, and optimal experimental design. In the short term, the code
will be put to use in the analysis of data collected using the Scripps instrumentation
(e.g. the Gemini data). The long term industrial requirement of a seafloor electromagnetic
method is the development of a 3D conductivity model to assist in hydrocarbon
evaluation. The algorithm can be readily integrated into a future subsurface
3D conductivity-imaging package to provide this product.
Recent years have seen a dramatic increase by petroleum companies in marine
electromagnetic methods. This was motivated by the need to explore areas where
seismic methods perform poorly, such as sub-salt, sub-basalt, carbonate terrains,
and by the potential to use controlled source EM methods (CSEM) to map gas hydrate
While there are many options for 2D MT modeling and inversion, there are serious
limitations on access to and design of the very few 3D codes in existence. Furthermore,
we note that CSEM and MT data have complementary resolutions to geological structure
and may also be efficiently collected together as part of the field operation.
Thus, there is a clear need for a joint CSEM/MT modeling and inversion capability.
This task is greatly facilitated by using the same underlying algorithm design.
Project researchers propose to develop a modeling code based on a fully 3D finite
element analysis for marine geophysical electromagnetic exploration. The project
has many components of the proposed package already in place, such as an existing
unstructured tetrahedral mesh generator with local refinement capabilities for
detailed representation of bathymetry and sub-seafloor heterogeneities. However,
several new features are required for this application.
A major task of this research is thus to implement a new hybrid edge-element
approach. Specifically, the formulation involves modification of the hybrid
A-ª method developed by electrical engineers at Graz University, Austria.
A common framework for planewave (MT) and dipole (CSEM) excitations will be
adopted and an efficient matrix-free QMR solver will be used. While these design
features enable the code to operate efficiently on a single desktop workstation,
the entire algorithm can be readily ported to inexpensive distributed-memory
parallel computing clusters now commonly found within the exploration groups
of petroleum companies.
Current Status (August 2005)
Project is complete.
Project Start: March 27, 2002
Project End: March 26, 2004
Anticipated DOE Contribution: $210,000
Performer Contribution: $340,000 (62 % of Total)
NETL - Rhonda Jacobs (firstname.lastname@example.org or 918- 699-2037)
SNL - David Borns (email@example.com or 505- 844-7333)