Project Management in the Oil and Gas Industry

Precedence diagram
Start
A
B
C
Finish
D
E
F
No.
ES
EF
D
LS
LF
Activity
D: Duration
ES: Early Start
EF: Early Finish
LS: Latest Start
LF: Latest Finish
Figure 3.6 Method of preceding diagram.

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98 
Project Management in the Oil and Gas Industry
analysis is used in a number of areas of the computer industry, construction 
industries, and in planning the shutdown for maintenance in refineries.
This analysis has confirmed its applicability and importance by its appli-
cation in different projects. Contracting companies can use it successfully 
because of its role in solving problems of coordination between various 
activities in a project that have considerable degrees of complexity and its 
role in planning the time required for implementing each activity. This 
method has made it possible to complete a project within the time planned 
and the overall schedule. 
PERT was developed primarily to simplify the planning and scheduling 
of large and complex projects. It was able to incorporate uncertainty by 
making it possible to schedule a project while not knowing precisely the 
details and durations of all the activities.
Hence, the PERT method depends on using statistics and probability 
theory, so it is now the main key for the project risk assessment from the 
time schedule point of view.
In some cases, it is required to compress the time schedule and items by 
a crashing technique as to reduce the time and calculate its impact out the 
cost and let them work overtime. The other way is by using a fast tracking 
method. This is done by letting some activities be in parallel which are 
usually in series. As we discussed, in the oil and gas industry, time is very 
critical. For example, we can start to construct the foundation for a petro-
leum processing plant before finishing 25 percent of the engineering deliv-
erables. Fast tracking often results in rework and usually increases risk.
Any dependencies between activities require specification of a lead or 
lag to accurately define the relationship. An example of lead in a start-
to-finish dependency with a ten day lead is in a case where the successor 
activity starts ten days before the predecessor has completed. An example 
of a lag is when there might be a desire to schedule a two week delay (lag) 
between ordering the equipment and using or installing it.