|
| | 講演要旨(英文) | | A computer program has been developed to evaluate time-domain electromagnetic (EM) responses for a one-dimensional (1D) model with multiple source and receiver dipoles that are finite in length. The time-domain solution is evaluated by a fast Fourier transform and a spline interpolation for efficiency. With the use of this code, we calculate step-off responses for hydrocarbon (HC) reservoir models. Although the vertical electric field has much smaller amplitude of signal than the horizontal field, vertical currents resulting from a vertical transmitter are sensitive to resistive layers. The modeling shows a significant difference between step-off responses of HC- and water-filled reservoirs, and the contrast can be recognized at late times at relatively short offsets. We empirically found that a point-source response is almost identical to an elongated-source response when the dipole length is less than a half of the offset distance, and the difference is as small as 10 %. |
|
|
|
| |
|