Method for correcting amplitude and phase differences between time-lapse seismic surveys

A method for processing:

• (i) a first seismic image of a sub-surface volume of interest that has a first trace and was produced at a first time, and a second seismic image of substantially the same sub-surface volume that has a second trace and was produced at a second time that followed said first time by a span of time during which there was likely to be a change in the sub-surface volume of interest, to produce an image of the sub-surface volume of interest with reduced noise, the first and second traces forming a common trace pair, the method comprising:
• cross-correlating the common trace pair to produce a correlation wavelet;
• decomposing said correlation wavelet to obtain a composite source amplitude and phase spectrum;
• using said composite source amplitude and phase spectrum to reduce distortion caused by the near surface in an image of the sub-surface volume of interest.

A seismic data processing method for producing an improved time-lapse image of changes in the bulk rock properties associated with a reservoir due to the reservoir process of interest, the method for use with time-lapse imaging that involves:

• first performing a first seismic survey of the reservoir at a first time;
• wherein said step of first performing including providing a source of seismic energy at a source location and a receiver of seismic energy at a receiver location;
• wherein said step of first performing includes using said source of seismic energy to propagate seismic energy through the rock associated with the reservoir;
• wherein said step of first performing includes using said receiver to receive the seismic energy that has propagated through the rock and produce a first signal representative thereof;
• wherein said first signal associated with said source and receiver is referred to as a first trace;
• second performing a second seismic survey of the reservoir at a second time with said source of seismic energy at said source location and said receiver of seismic energy at said receiver location;
• wherein said step of second performing includes using said source of seismic energy to propagate seismic energy through the rock associated with the reservoir;
• wherein said step of second performing includes using said receiver to receive the seismic energy that has propagated through the rock and produce a second signal representative thereof;
• wherein said second signal associated with said source and receiver is referred to as a second trace;
• wherein said second seismic survey is likely to be subject to at least one distortion that was not associated with said first seismic survey;
• wherein said first trace and said second trace form a trace pair, the method comprising:
• measuring similarities between said first trace and said second trace;
• using said similarities to identify differences between said first trace and said second trace;
• removing at least one of said differences to produce an improved time-lapse image of the changes in the bulk rock properties associated with the reservoir between said first time and said second time that are due to the receiver process of interest.