With the increasing number of laterals or extended horizontal-well depths, operators are seeking to maximize zonal control using intelligent completions. Electrohydraulic (EH) control systems introduce substantial reservoir-control advances by combining the benefits of both hydraulic and electric systems. This paper focuses on the features and benefits of a new EH control system, its reliability, and its overall performance when paired with interval control valves (ICVs) and other equipment.
The EH control system presented in this paper uses a novel approach to zonal control. The EH system uses two hydraulic lines and one electrical line to control up to 12 zones selectively. The system employs a unique addressing method that uses simple electronic components to selectively address different downhole tools. The system has the ability to provide the high motive power typical with existing hydraulic systems while providing fast system responses associated with electrical systems. Furthermore, system reliability is enhanced by fluid filling the electrical system with a pressurized non-conductive fluid biased to the external environment.
Careful consideration was given to both current electrical and hydraulic systems for deriving the system performance of the referenced EH system. One of the initial drivers for the EH system was the need to increase control while reducing the amount of control lines and surface infrastructure required to deploy such a system. Testing and deployment of the EH system suggests that the system response was able to meet or exceed current N+1 control systems while greatly increasing the amount of zones controlled. System response, system performance, surface infrastructure, ease of installation, number of control lines, and system modularity were assessed for this paper. Finally, the paper documents the cost savings and reliability obtained with the new EH module compared to traditional N+1 direct hydraulic control systems and current electrical systems.
This paper provides a thorough understanding of electric, hydraulic, and EH systems for downhole control in intelligent completions. It focuses on the comparison of all three systems but emphasizes the modularity of the EH system presented. Such modularity allows the EH system to be used in different intelligent completion applications while remaining compatible with other equipment deployed.