Design and Performance Evaluation of an Ultradeepwater Subsea Blowout PreventorControl System Using Shape Memory Alloy Actuators

摘要

As drilling moves to ultradeepwater, conventional blowoutrnpreventers (BOP) actuation technologies based on full orrnpartial hydraulics are unable to meet the API standard forrncontrol system response times because of long hydraulic fluidrncommunication path between an offshore platform and a BOPrnstack on the sea floor. Now that an ultradeepwater subsearnblowout preventer (SSBOP) control system using shapernmemory alloy actuators has been demonstrated in thernlaboratory, several practical issues can be addressed.rnThe experimental device uses nitinol smart alloy materialrn(SMA). It can be actuated by electrical heating, therebyrnreplacing hydraulic actuation and hydraulic lines with electricrncables. Alternatively, the SMA actuator system can bernactivated by chemical heating. With significantly fewerrncomponents, the SMA system will dramatically reduce totalrncost and will increase operation reliability. The new devicerncan easily be retrofitted to existing conventional subsearncontrol system thus enabling other methods to be used as arnbackup. Most importantly, the innovative all-electric BOP willrnprovide a much faster response than its hydraulic counterpartrnand will improve safety for subsea drilling. The BOP actuatorrnuses strands of SMA wires to achieve large force and largerndisplacement in a remarkably small space. Experimentalrnresults demonstrate that the BOP can be activated and fullyrnclosed in less than 15 seconds.rnThis paper considers chemical and thermal energy sourcesrnas alternatives to electricity and ways to trigger an automaticrnmechanism. Additionally, a model is used to calculate thernSMA length and diameter that will be required to providernsufficient force for different types and diameters of BOP ramsrn(blind, pipe, or shear) or the annular BOP, and the energyrnrequirements in each case. The model also addresses the rangernof pressures and temperatures that can be handled. Simpleguidelines are presented along with practical field examplesrnfor different types of BOP hook ups.