The key to successful 4D is repeatability. In earlier 4D surveys a significant proportion of errors were attributed to the difficulty of repeating the original acquisition. Factors including geometry changes, weather, tides, etc. all contribute to this error. Repeatability analysis requires a detailed knowledge of the underlying distribution of data. Concept Systems’ REFLEX attribute analysis software provides the ideal platform for repeatability analysis.
Repeatability analysis is now the core tool used by Concept Systems’ 4D services team to optimize repeatability in both the design and acquisition phases of a 4D seismic survey. In the design phase, the analysis is used to select the best geometry for the monitor survey. During acquisition, the repeatability may be carried out in-field or from the office and can quickly identify areas to target for infill to improve repeatability
Repeatability analysis is also useful in understanding differences between expected and actual 4D response on historic surveys. Where real fluid movements do not match the 4D seismic results, it is useful to assess the geometric repeatability to establish if the results in that section are reliable.
Concept Systems can provide repeatability analysis as an in-field or an office-based service. This service involves:
- Identifying the best trace match between monitor and baseline chosen using a user choice, matching function
- Creating spatial plots to display the repeatability performance for a variety of navigation attributes (as well as having the facility to compare seismic attributes if required)
- Outputting histograms or ASCII dumps of the matching results for any navigation repeatability attributes
- Providing all results and images on the Concept Systems e-services site as regularly as required
