Calculation

The calculation of the Start Time of each Operation is based on the Operations Duration and the defined Working Times.

The Operation Duration is calculated as follows:

•If Actual (hrs) is specified then Duration = Actual(hrs) else,

•If Adjusted (hrs) is specified then Duration = Adjusted (hrs) else,

•Duration = Planned (hrs). Note that Planned (hrs) is mandatory input but may be 0.00.

Note that Operations with 0.00 hrs Duration will not be shown on the Lookahead schedule unless they are tagged as Milestone. To show an Operation with 0.00 hrs Duration, which is not a Milestone, on the Lookahead schedule define a Duration of 0.001 hrs.

Operations tagged as Contingency can have a Duration longer that 0.00 hrs. However, for the calculation they will be treated as having no (i.e. 0.00 hrs) duration. This facilitates input of activities (consisting of one or more Operations) that are not planned for but may occur (e.g. round-trip for bit or tool failure, remedial cement job, etc.). By multi-selecting these Operations and removing the Contingency tag, they can be quickly included in the schedule calculation.

As defined in the project's working times, the working schedule may be defined as Unrestricted (working all days from 00:00 to 24:00) or Restricted (Work From and Work To defined or Non-working days active). For Unrestricted schedules, the first operations starts at the start date & time as input in the Project Data dialog. The start date and time of each subsequent operation is then calculated by adding the Duration of the current operation. On a Restricted working schedule, the duration will be split across non-working hours and/or non-working days. The effect of this is shown below.

No split operations

If the working schedule is Restricted, the column 'No split' becomes visible in the Operations grid (see above image). If an Operation is tagged as No Split and the working schedule is Restricted, the Operation will not be split across non-working time (i.e defined non-working hours or non-working days). The Operation will then start at the next available date and time and the next operation start will be calculated by adding the Duration (hrs) thereto. This has two implications:

1.If a Restricted working schedule is defined all 'no split operations' may not have a duration that is longer than the available working hours in a day. Likewise, changing the restricted working times is only allowed if there are no 'no split operations' defined with a duration that exceeds the new working hours for a day.

2.If a 'no split operation' is moved to start of the next available start time, its end time (start time of next operation) is calculated from the new start date and time. However, the Cumulative Days (Planned, Adjusted and Actual) are calculated from the original start date and time (i.e. the end date and time from the previous operation) in order to reflect the correct project duration.

The effect of 'no split' is shown below.

Long Operation may be split

The Operation may be suspended and continued the next available working hours.

Long Operation may not be split

The Operation may not be suspended and completed once started. It will then start at the next available start date and time (at which it can also be completed).