Method for monitoring a multi-layered system
AssigneeShell Oil Company
InventorsFredrik Hansteen, Peter Berkeley Wills
Life of this patent
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Abstract
A method for monitoring a multi-layered system below a surface comprising a slow layer and a fast layer; the method comprising: transmitting one or more seismic waves from one or more seismic sources through the multi-layered system; receiving signals emanating from the multi-layered system in response to the one or more seismic waves with one or more receivers located a distance from the one or more seismic sources; identifying one or more critically refracted compressional (CRC) waves amongst the signals; and inferring information about a change in the slow layer based on the one or more CRC waves; wherein the CRC wave is a refracted wave which has traveled along an interface between the fast layer and an adjacent layer.
Claims10
A method for monitoring a multi-layered system in a subsurface formation that includes a slow layer and a fast layer;
- the method comprising:
- a) providing a set of signals obtained by:
- i) transmitting one or more seismic waves from one or more seismic sources through the multi-layered system;
- and
- ii) receiving signals emanating from the multi-layered system in response to the one or more seismic waves with one or more receivers located a distance from the one or more seismic sources;
- wherein at least one of said seismic sources and receivers is in a well;
- b) identifying among the received signals at least one critically refracted compressional (CRC) wave that has traveled along an interface between the fast layer and an adjacent layer;
- c) performing steps a) and b) in a time-lapse mode so as to obtain at least two CRC waves;
- d) inferring information about a change in the slow layer based on the at least two CRC waves;
- and
- e) imaging the information from step d).
Dependencies are inferred from the claim text.