67 results about "Controlled source electro-magnetic" patented technology

The system and method for real-time monitoring of a hydrocarbon reservoir (4) during extraction include an electro-magnetic source assembly (16) for transmitting a first plurality of electromagnetic fields. A plurality of seafloor antennae (30a–30d) is distributed over an area of the seafloor (8) corresponding to the reservoir (4), where each antenna (30a–30d) comprises recieves electrode array (30a–30d) adapted for receiving a second plurality of electromagnetic fields and generating signals corresponding to the detected fields. A data logging processor receives the signals over time and stores data corresponding to the signals. Different combinations of the receiver electrode are used in combination with transmitter antennae for measuring vertical, radial and / or azimuthal fields. Transmission and detection of the fields can be performed continuously or at timed intervals during hydrocarbon extraction to estimate the rate and efficiency of extraction.

A method of analysing results from an electromagnetic survey of an area that is thought or known to contain a subterranean resistive or conductive body within a background strata configuration is described. The method comprises providing a set of electromagnetic field data obtained using at least one electromagnetic receiver and at least one electromagnetic source for a range of source-receiver separations, e.g. providing conventional controlled-source electromagnetic survey data. A subset of the electromagnetic field data is identified that comprises data obtained for source-receiver separations greater than a selected threshold offset. The threshold offset is chosen so that data beyond this offset are characteristic of magnetotelluric data. Thus the subset of data is then processed in accordance with a first technique to obtain information on the background strata configuration. Other electromagnetic field data obtained for source-receiver separations less than the threshold offset may then be processed in accordance with a second technique to obtain information on any subterranean resistive or conductive body within the background strata configuration.

A method for removing the air wave effect from offshore frequency domain controlled source electromagnetic survey data. The region of interest is modeled with (111) and without (113) a top air layer. The electromagnetic field due to the source is computed at the survey receiver positions for each source position for both models. The difference between the fields computed (116) from the two models is the air wave effect, which is then subtracted (117) from the field data for the corresponding source-receiver geometry.

A method for tracking a sinusoidal electromagnetic signal in noisy data using a Kalman filter or other tracking algorithm. The method is useful for controlled source electromagnetic surveying where longer source-receiver offsets can cause the source signal to decay significantly and be difficult to retrieve from magnetotelluric or other electromagnetic background.

Method for efficient processing of controlled source electromagnetic data, whereby Maxwell's equations are solved [107] by numerical techniques [109] such as finite difference or finite element in three dimensions for each source location and frequency of interest. The Reciprocity Principle is used [103] to reduce the number of computational source positions, and a multi-grid is used [105] for the computational grid to minimize the total number of cells yet properly treat the source singularity, which is essential to satisfying the conditions required for applicability of the Reciprocity Principle. An initial global resistivity model [101] is Fourier interpolated to the computational multi grids [106]. In inversion embodiments of the invention, Fourier prolongation is used to update [120] the global resistivity model based on optimization results from the multi-grids.