In order to track operational performance and efficiency, daily activities (operations) are labeled with an Event Class.  These fields are used to produce time distribution reports for post-well performance reviews and comparisons.

 

Planned events

Planned events are activities that are executed as part of the normal (planned) sequence of events.  Typically, these events are described in the drilling program.

 

Unplanned events

All activities that were not foreseen or planned (i.e. not part of the drilling program) are considered to be Unplanned Events.

 

Non-productive time (NPT)

If activities are delayed or interrupted, this is considered to be non-productive time (NPT). Non-productive time can occur during Planned and Unplanned events.

 

Service Interrupt (SI)

A Service Interrupt is non-productive time caused by a third-party (service) company. A Service Interrupt does not necessarily have to be down-hole. 

Any interruption to (or delay in) ongoing operations, that is caused by a third-party service company, is considered a Service Interrupt. 

 

By convention, an activity that is labeled as a Service Interrupt must also be an NPT event.

Wait on Weather (WOW)

The time by which Planned or Unplanned events are suspended or delayed due to weather circumstances, is considered Wait on Weather time.  This can be the inability to offload a supply vessel or supply pipe to the rig floor due to high winds (i.e. inability to work the crane) but also the inability to supply a land rig due to weather (road) conditions, etc. etc.

 

Event class assignment

Resulting from the above definitions, an activity is either a Planned or an Unplanned event.  In addition, the activity may be labeled as NPT, a SI or WOW.

As such, there are a total of 8 Event Classes that may chosen from when labeling an activity;

 

 

Root cause

For any activity that is labeled as non-productive time or service interrupt, a Root Cause must be provided.  Failure to do so will result in an error message when attempting to save the daily activity record.

Some examples of root causes are given below, but other may be added as required through Lookup Data Maintenance.

 

 

Determining the correct event class

The distinction between Planned and Unplanned activities in itself is fairly clear.  If the activity is part of the planned sequence of operations, which is normally described in a detailed drilling program, it is considered a Planned event.  If the activity was not planned (i.e. not in the drilling program), it is an unplanned event. Non-productive time and Service Interrupt is added when either of these activity classes are interrupt or delayed.

 

A good example is a sidetrack.  If the sidetrack occurs for geological reasons and it was planned for in the drilling program, all activities for the sidetrack (including setting a cement plug, dressing off cement, etc.) should be considered to be "Planned events" (P).

 

On the other side, if a sidetrack becomes required due to a BHA lost in hole, this will change.  The time from becoming stuck in hole - which occurred during a planned activity (i.e. drilling the hole section) - should be labeled as "Non-productive time during a Planned event" (PN).  This is continued until a cement stinger is run in hole to set a sidetrack plug.  From that moment onwards, activities become "Unplanned" (U). 

 

However, as long as (and this is important!) the "Unplanned" activities take place without problems, the event should not be labeled as NPT or Service Interrupt!  On the other side, if a mud motor failure occurs whilst attempting to sidetrack of the cement plug, then the activity becomes "Service Interrupt during an Unplanned event" (US) because it is non-productive time (NPT) caused by a service interrupt (SI).

 

The "Service Interrupt during an Unplanned event" (US) should be continued until a new mud motor is back on depth and sidetrack operations are resumed.  Note however that it is acceptable to label specific (intermediate) activities as "Unplanned" (U) during this period.  For example, if the topdrive was serviced during the round-trip to replace the mud motor, this time could be considered as "Unplanned" (i.e. not part of the service interrupt time).

 

The "Unplanned" (U) event time should continue until the sidetrack has reached the same measured depth as where the BHA became stuck in hole.  From this point onwards, the activities become "Planned" (P) again.

 

Another example would be a wiper trip prior to running surface casing (i.e. after drilling top hole).  If it was planned anyway (e.g. based on offset well results) this activity should be considered "Planned" (P) events. However, if wiper trips were never required on the offset wells (and thus not planned for), a wiper trip performed because of sudden hole problems whilst pulling out of hole with the drilling assembly, should certainly be classed as "Unplanned" (U).