Project Portfolio Integration (focusing on the schedule only)

Primavera Version: P6 Release 7 SP4

Given situation:

1) A very large Oil & Gas EPC project portfolio that was divided into 6 major project areas.

2) Each area EPMC/S Level 3 (WBS is down to the Work Package Level) schedule is approximately 10,000 activities. EPMC/S means Engineering, Procurement, Modularization/Fabrication, Construction and Commissioning/Start-up.

3) I have to contend with a total of 60,000 activities where there were about 100 key milestones per area and about 200 Interface Milestones to manage and closely monitor.

4) The project is expected to complete in 6 to 7 years.

Question:

1) What is the best approach and/or method of integrating all the project area schedule using the Primavera scheduling tool we have at present?