De-manning of offshore processing facilities presents an opportunity for significant CAPEX and OPEX savings for operators, is inherently safer and may be an enabler for marginal oil and gas developments.

Unmanned wellhead platforms are common, however de-manning of significant oil and gas processing facilities has not been achieved to-date.

This paper presents a conceptual design for a Normally Unmanned Installation (NUI) with full processing of well fluids to export specifications. By using novel and innovative solutions, a design with reduced equipment count, platform weight and attendance is proposed. The design is technically ready for implementation whilst meeting the functional requirements of an offshore processing facility.

A functional specification was developed for the platform; it was important that the design is transferrable, therefore this functional specification was kept broad. The platform was expected to process well fluid to typical pipeline export specifications. To test the design, commerciality was tested against a "Reference Case", traditional manned platform. Full subsea processing was investigated but discounted due to a lack of technical readiness.

Traditional approaches to platform design were challenged at every level, from platform access methods to the requirement for platform power generation. The key drivers for manning were investigated, identifying the target areas for simplification. An optimal platform design was then identified integrating the latest techniques and technology.

The NUI CAPEX was compared versus the Reference Case. Ground-up OPEX estimates were prepared to quantify the reduction in attendance and achievable savings.

The resulting NUI design achieves an approximate 60% reduction in equipment weight compared with a traditional manned platform, leading to a CAPEX reduction of around 30%. Significant reduction is achieved by removal of living quarters, and therefore life support systems from the facility. Power import allows maintenance-heavy power generation to be removed.

The optimised NUI delivers a reduction in OPEX of around 50% when compared to a traditional manned facility. Digital strategies such as predictive maintenance, robotic inspection and remote monitoring reduce the reactive maintenance hours offshore by up to 85% while maintaining platform availability. Walk-to-Work platform access is a mature technology and offers cost savings when compared with helicopter access and there is the potential for sharing of walk-to-work systems between assets and industries. Walk-to-Work access has the advantage that no permanent living quarters are required. A significant reduction in fabric maintenance manhours is achieved by carrying out inspection remotely.

The truly innovative and disruptive solution for unmanned facilities is the subsea factory on the floor. At the time of writing, the technology is not of the required maturity and it does not offer a viable solution. As this technology matures the potential exits to create a truly differentiated, facility of the future.

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