5.3.3 Log

The WITSML 2 Log is very simple object, in that it is primarily just a container for one or more ChannelSets as show in Figure 5.3.3-1 . Most of the information is at the ChannelSet level. The concept of multiple ChannelSet in a single Log is significant change from WITSML where each Log represented exactly one group of curves and their data (NOTE: Technically, the WITSML 1.4.1.1 Log allowed for multiple blocks of data, but this was just to optimize transmission of sparse data for real time. With ETP, this requirement no longer exists.). In WITSML 2, each ChannelSet represents a disjoint set of channel data. There are many possible use cases that would dictate what ChannelSets would go together in a Log, and how they would relate to each other.

Figure 5.3.3-1 Organization of channel data within a log

Some of the possibilities:

• A Log could contain a depth run in one ChannelSet with the data for a re-log of one section of the hole in another ChannelSet.
• A single Log could contain all of the data for a run of a Production Logging Tool (PLT).

• Data from multiple acquisition systems can be represented as multiple ChannelSets in a Log.

The Log object does not include any specific information about how the ChannelSets relate to each other, except as can be gleaned from a comparison of the metadata for each object in the log.