Repeatability and 4D Seismic Acquisition
Published:January 01, 2013
Recall from Chapter 1 that our ability to obtain an interpretable 4D seismic data set is a function of both detectability and repeatability. Chapters 3 and 4 have concentrated on detectability. Now we focus on repeatability - a quantity that has been alluded to but not yet fully defined. Repeatability is simply a measure of the similarity of two or more vintages of seismic data, and a primary goal of 4D seismic acquisition and processing is to maximize repeatability. That can come at a cost. As a result, the effort put into acquisition (and to a lesser extent, into processing, which is discussed in Chapter 6) must be balanced by the expected level of 4D detectability and by factors such as water depth, reservoir depth, sea-bottom conditions, and operational constraints.
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Practical Applications of Time-lapse Seismic Data
Time-lapse (4D) seismic technology is a key enabler for improved hydrocarbon recovery and more cost-effective field operations. Practical Applications of Time-lapse Seismic Data (SEG Distinguished Instructor Series No. 16) shows how 4D seismic data are used for reservoir surveillance, how they provide valuable insight on dynamic reservoir properties such as fluid saturation, pressure, and temperature, and how they add value to reservoir management. The material, based on the 2013 SEG Distinguished Instructor Short Course, includes discussions of reservoir-engineering concepts and rock physics critical to the understanding of 4D data, along with topics in 4D seismic acquisition and processing. A primary focus of the book is interpretation and data integration. Case-study examples are used to demonstrate key concepts and are drawn on to demonstrate the range of interpretation methods currently employed by industry and the diversity of geologic settings and production scenarios in which 4D is making a difference. Time-lapse seismic interpretation is inherently integrative, drawing on geophysical, geologic, and reservoir-engineering data and concepts. As a result, this book should be of interest to individuals from all subsurface disciplines.