Electric actuation of a surface controlled subsea safety valve

Abstract

The growing technology associated with petroleum equipment has lead to an increase in electrical components used to measure, adjust and control many aspects of the petroleum extraction process. This increase in electrical use has lead to the conversion of many components from hydraulic operation to electric. Therefore, it is the purpose of this report to detail and propose an engineering solution to the electrical conversion of a surface controlled subsea safety valve (SCSSV). Preliminary analysis has resulted in the following important functional requirements that the SCSSV should operate within: Temperatures up to 350 F. Estimated operational life of 20 years. Peak available power of 4300 W (actual value will be much lower than this due to other power system drains). The three conceptual designs presented in this report are the following: Electric motor actuator with a solenoid latching detent. Linear actuation with a fluid reservoir locking valve. Rotational engagement with an electric locking clutch. After reviewing and comparing these concepts, the last concept was chosen to be further developed. This concept will have the least temperature sensitive components and fewer leak path problem areas. Upon completion of the detailed design phase an electric SCSSV solution has been proposed. The following is a brief list of the performance claims: Power requirement to open: 0.5 W. Time required to open valve: 10 minutes. Installable inline with 4-1/2 tubing. Operating temperature range: 20-350 F. H₂S service certified. Hold open energy requirements 0~0.2 W. There are however practical issues that must be addressed to ensure reliable and satisfactory performance of the SCSSV. The actual efficiency of the cylindrical cam mechanism and reliability of the torque overload clutch must be empirically determined due to the number of theoretical assumptions used. Thus these items should be thoroughly tested in order to produce a reliable and satisfactory SCSSV. It is with these claims and working issue that this electrically converted SCSSV be fully developed and installed for electrical petroleum production systems.