5.3 Log Organization
|For Standard||WITSML v2.0|
The Log data object underwent major redesign in v2.0. The main driver for this design change was so that realtime data could be streamed using ETP. Figure 5.3-1 is a UML diagram of the v2.0 Log. At a high level, a Log is now organized as follows:
- Channel: corresponds roughly to the LogCurveInfo structure in WITSML v220.127.116.11 and directly corresponds to the ChannelMetadataRecord structure in ETP. In historian terminology, a Channel corresponds directly to a tag. Channels are the fundamental unit of organization for WITSML logs.
- ChannelSet: grouping of Channels with a compatible index for some purpose. As discussed earlier, each Channel effectively has its own index. By compatible index, we simply mean that all of the Channels are either in time or in depth using a common datum
- Log: primarily a container for one or more ChannelSets. Most of the information is now at the ChannelSet level. The concept of multiple ChannelSet in a single Log is significant change from WITSML v18.104.22.168 where each Log represented exactly one group of curves and their data
This chapter further explains these concepts and guidelines for working with this new design.