Intelligent subsea control

Abstract

The production control system provides control of all functions of the subsea production system. Conventionally, subsea functions include operation and control of: down hole, safety valves, subsea chokes, production valves mounted on the x-mas tree and utility functions such as monitoring of fluid characteristics, pressure leakage, valve positions, etc. The subsea system comprises a wellhead, valve tree (x-mas tree) equipment, pipelines, structures and piping systems among others. In many cases a number of wellheads have to be controlled from a single location. The control system provides operation of valves and chokes on subsea completions, templates, manifolds and pipelines. The design of a control system must also provide a means for safe shutdown on failure of equipments or loss of electrical/hydraulic control from the topside (a platform or floating facility) and other safety features that automatically prevent dangerous events. Presently there are no tools for early fault detection and diagnosis in the subsea control systems area. Troubleshooting and fault finding are normally performed with procedures when the fault is already affecting the system performance and, in most cases finding the root cause of the fault is not straight forward. This fact affects subsea operations and does not provide any support for maintenance plans. Intelligent supervision, fault detection and diagnosis techniques successfully applied to other oil industry related processes are perfectly applicable to subsea technology.