Multizone single-trip gravel-pack (MZ-STGP) completion systems not only save rig time to complete wells with long multilayer intervals but can significantly reduce capital and operational expenditures by standardizing completion design and simplifying operation complexity. It can also help improve quality, health, safety, and environment (QHSE) performance for a long-term project development.
This paper discusses a case history of an operator in Indonesia developing a major offshore field primarily with MZ-STGP completion systems to produce marginal reservoirs. A MZ-STGP system was selected to reduce multizone gravel-packing operation time as compared to conventional stacked-pack systems. The main focus was to standardize completion design and help improve system reliability and operational efficiency, which is associated with both logistic preparation and field execution. Despite exploring cost-effective solutions, operational safety—including well control, particularly for developing a shallow-gas field—was the number one priority, as usual. A new concept type of safe running system was developed and implemented as part of a field operation standard to help ensure a safe and efficient operation.
Based on MZ-STGP system trial results and lessons learned during the early stage, a standard MZ-STGP completion instruction was approved and applied as a guideline to standardize completion operation and identify and mitigate potential operational risks quickly to improve safety, performance, and efficiency. By understanding the principle of MZ-STGP system limitations, the system-working envelope was expanded and refined without jeopardizing system reliability and performance.
With more than 170 wells with MZ-STGP installation and more than 650 zones gravel packed in a 12-year time span, a case history review provides an opportunity to share lessons learned and fundamental success factors and explore the future of this technology.