8.2.2 Well Construction and Maintenance Ledger (Event Ledger)

Topic Version1Published11/11/2016
For StandardWITSML v2.0

NOTE: Energistics common now provides an activity model data object, which may be implemented as an alternative to the well CM ledger.

The "event ledger" concept is this: each time an activity associated with a well happens (an "event" as defined in Section Event: Definition , Event: Definition ) it is recorded in the ledger, which is named the well construction and maintenance ledger.

Recording this information tracks the history of all events and makes it possible to derive the complete history of the completion, including the use cases described above. A single event entry fills an instance of the data object well CM Ledger and can contain this information:




Well and wellbore name, event name, etc.

Event details

More detailed information about the operation of an event, e.g. depths, type, times, duration, etc.

Completion equipment reference

References to the downhole string (see Downhole String Set , Downhole String Set ), and the string equipment component being worked on within this string.

Operational and management information

Business associate, work order number, cost, rig ID, flags to indicate if the operation was planned or unplanned, etc.

Event Extension

Contains a reference to a WITSML data object containing the job data. These are listed as elements that reference AbstractEventExtension in the well CM ledger data object.


A reference to any WITSML data object associated with the event.