Requirements of Downhole Flow Control Valves

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA brief review of Down Hole Flow Control technology shows that it is still far from mature. Efforts on characterizing DHFC valves highlight some fundamental challenges, and indicate that DHFC valves are flow control devices, not pressure control devices as chokes are. The DHFC valve requirements are then detailed, including the functionality, mechanical, and reliability requirements and other considerations, and an attempt is made to dispel some of the misconceptions. Some simple guidelines for system/valve design and selection are also presented, providing a useful tool for the user. An example is given, demonstrating the complexity of the interactions of multiple well and reservoir parameters and some of the design basics, and the use of a simple spreadsheet simulator.It is concluded that while the DHFC technology has proved itself as viable and capable of delivering huge value to the industry, there remain some serious technical challenges, which call for continued and concerted efforts. The complex requirements should be managed with a system approach not just focusing on discrete components. Analytical tools are needed for proper system design and validation in the given application environment to achieve success.

Robust observer‐based control for uncertain discrete time‐delay systems with nonlinearities electric‐hydraulic system under Hölder condition

“…In this work, we consider the electro-hydraulic system studied in previous studies, 26,27 which consists of surface hydraulic supply unit and subsea parts: servovalve and hydraulic actuator. The hydraulic actuators' displacement is controlled by the surface hydraulic supply unit and the servovalve.…”

“…In Section 3, a new Lyapunov-Krasovskii functional that accounts for both the nonlinearities and the dependent noises will be proposed, and Lyapunov stability theory and LMI optimization approach will be used to guarantee the asymptotically stable of the system and achieve the minimal H ∞ -norm bound for the state feedback control system. In Section 4, subsea electric-hydraulic control system will be studied to illustrate the proposed observer and get the minimal H ∞ -norm bound; different from the researchers studied in other studies, [26][27][28] the electric-hydraulic system in this paper contains parameter uncertainties, hydraulic delay, and nonlinear resistance under Hölder condition as influenced by control fluid viscosity, hydraulic shock, and sediment concentration. And conclusion is given in Section 5.…”