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Integrated Asset Management and Optimization Workflows 233

coupling workflow. When interfacing with parallel and distributed com-
puting systems, the controller carries dual functionality:
– Constructs the message packets and forwards them to the distributed
system annex which contains a set of parallel virtual machine (PVM)
system calls to communicate with the running PVM daemon.
– Communicates with the network and reservoir simulator through an
open interface, which contains the PVM connectivity and controls
the communication between the host computers.
Fig. 6.13 shows an example of a tight coupling architecture extended with
PVM connectivity.
• Loose-coupling scheme, at specific time intervals, when two or more reser-
voir simulators are coupled to a network with common global con-
straints: The workflow allocates global production and injection
targets to the principal groups of surface networks at the start of each syn-
chronization step. When the synchronization steps overlap with the res-
ervoir simulation time-steps, the loose-coupling scheme becomes an
explicit-coupling scheme.
• Explicit coupling, when the balancing between reservoir simulator and
surface network is performed exactly at the start of each simulation
time-step. Fig. 6.10 above shows an example of an explicit-coupling
scheme.
The IAM workflow was deployed and extensively validated in five scenarios
(Khedr et al., 2009) according to the business plan constraints that mandate

Fig. 6.13 Architecture of the coupled reservoir simulation and surface network system
with PVM connectivity. (Modified from Ghorayeb, K., Holmes, J., Torrens, R., Grewal, B.,
2003. A General Purpose Controller for Coupling Multiple Reservoir Simulations and Surface
Facility Networks. SPE-79702-MS. https://doi.org/10.2118/79702-MS.)