Magnetotellurics At Coso Geothermal Area (2006)

GEOTHERMAL ENERGY

Exploration Activity: Magnetotellurics At Coso Geothermal Area (2006)

Exploration Activity Details
Location	Coso Geothermal Area
Exploration Technique	Magnetotellurics
Activity Date	2006
Usefulness	useful
DOE-funding	Unknown

 

Exploration Basis

Use magnetotelluric data to model the reservoir.

 

Notes

Magnetotelluric (MT) data from 101 tensor stations over the East Flank of the Coso geothermal field, southeastern California, were inverted on a PC using a 3-D Gauss-Newton regularization algorithm based on a staggered-grid, finite difference forward problem and jacobians. Static shifts at each MT site can be included as additional parameters and solved for simultaneously. Recent modifications to the algorithm developed here include the addition of an LU solver to calculate the model parameter update, to reduce storage. The inversion for the Coso data set was started from a 22 ohm-m half-space and results qualitatively resemble models from 2-D transverse magnetic (TM) inversions, and from massively parallel 3-D inversion by other workers. In particular, a steeply west-dipping conductor was resolved under the western East Flank tentatively correlated with a zone of high-temperature ionic fluids. Implementation on desktop serial PC's is an attempt to widen the potential user base. Run times for the Coso data set on a 3.4 GHz desktop are 2-3 days, with the greatest amount of run-time taken up in computing the Jacobian matrix explicitly using reciprocity. Continuing efforts are being made in storage efficiencies, in speeding the Jacobian computations, and improved parameter weighting.

 

References

• Maris, V.; Wannamaker, P.; Sasaki, Y. (1 January 2006) Three-Dimensional Inversion of Magnetotelluric Data on a PC, Methodology and Applications to the Coso Geothermal Field