DOT 2010: Benchmarking aids deepwater field design, production efficiency
The offshore industry would benefit from a consistent periodic approach to performance benchmarking for deepwater facilities, according to Thomas Gray of consultants Ziff Energy.
HOUSTON -- The offshore industry would benefit from a consistent periodic approach to performance benchmarking for deepwater facilities, according to Thomas Gray of consultants Ziff Energy.
In a paper presented at DOT, Gray said that external benchmarking by an independent third party can provide an objective analysis of a field’s operating costs and production efficiency, based on performance data from similar fields.
In the development phase, this performance data can assist with concept selection, project economic analysis, operating budget preparation, and performance targets.
During the plateau output phase, when actual field costs and production performance are relatively stable, Gray added that benchmarking data can be useful to make comparisons with other similar projects concerning well operations, maintenance procedures, logistics, and so on. And during a field’s tail-end phase, benchmarking can provide pointers for new approaches to improve operating efficiency.
Deepwater fields bring unique challenges and issues for valid benchmarking, Gray said. These include high cost and long-lead time well operations; subsea maintenance and ROV operations; injection well and artificial lift systems; flow assurance systems; and FPSO/FSO/shuttle tanker lease fees.
Also, there are relatively few deepwater fields in operation. In this case, the benchmark study design involves finding a group of fields similar in characteristics and then understanding how results are impacted by the differences. Unique deepwater characteristics that can be used for peer comparisons include wet versus dry trees, export method, type of facility, location, and water depth.
Deepwater cost benchmarking is complicated because even in apparently similar fields, costs may vary significantly in a study year. Anomalies can arise depending on the scope of artificial lift, well workovers, or subsea repairs. These anomalies must be considered when looking at benchmark results, Gray stressed.
For production benchmarking, deepwater facilities present many of the same challenges in maintaining output as fields in conventional water depths. But deepwater facilities also have special problems, notably the impact of weather and metocean conditions, which vary widely across the globe. A hurricane in the Gulf of Mexico can shut down production for days or months – longer if facilities incur damage.
Among benchmark studies of deepwater facilities to date, some lessons have been learned, Gray said. Results show that most of these facilities produce at rates below their design capacity, up to 50% below in some cases. Facilities are often sized and designed based on limited reservoir data, produced fluid properties, and well performance data. Larger facilities can be justified given uncertainties over future performance and expansion plans, but this does lead to higher development capex.
Other benchmark studies have shown that higher complexity fields cost more to operate. The benchmark data, however, helps the operator to better understand the cost consequences of complex designs and to better compare the performance of facilities.