Wavelet Control Allows Differencing of 3D from 2D—ENTEC/Lloyd Weathers
Time-lapse seismic is sometimes referred to as 4-D seismic with calendar time between successive 3-D surveys as the fourth dimension with the objective of monitoring depletion and bypassed pay by acoustic changes due to fluid production. But what if no reference 3-D survey was acquired before production started? Production began in many of today's fields before 3-D seismic was commonly available, but old 2-D seismic is almost always available. The ability to produce accurate difference sections between such disparate surveys expands the potential applicability of time-lapse seismic.
Figures & Tables
“This book, prepared for use with the first SEG / EAGE Distinguished Instructor Short Course, discusses Â"time-lapse seismicÂ" and enables geoscientists to assess the value and risk of this new technology. It covers the rationale and driving forces behind time-lapse seismic by examining the limitations of existing methods of tracking fluid flow between wells. It examines those reservoir properties that change with time and what can be observed on seismic data over elapsed time. The repeatability of seismic data and the use of Â"legacyÂ" data sets are discussed, along with a review of the seismic data acquisition schemes and data processing requirements for time-lapse analysis. The rock-physics foundation for data analysis and interpretation options also are described. A selection of industry case histories illustrates many of these points. The reader will gain an understanding of key success factors, key calibration requirements, and key uncertainties of time-lapse seismic in reservoir management.”