Current Status and Techniques of Equipment for Depressurization Exploitation of Marine Gas Hydrate
The China Geological Survey has successfully implemented two natural gas hydrate production tests in the Shenhu sea area using depressurization method,achieving multiple major breakthroughs in drilling and pro-duction technologies of hydrate in deepwater shallow soft formations.However,there are still problems such as low single well production,complex exploitation supporting equipment and weak economic applicability.In order to support the exploitation plan of the third depressurization production test in the Shenhu Sea area,the influential fac-tors of depressurization exploitation technique on exploitation equipment were systematically sorted out.The adapta-bility of subsea Christmas tree structure for conventional oil and gas exploitation was compared and analyzed,and a set of key technical theories for subsea horizontal Christmas tree suitable for deepwater gas hydrate exploitation was proposed.The technologies such as"integrated"Christmas tree body,dual crossing structure subsea crossing de-vice,fail safe hydraulic control subsea valve and driver,and composite electrohydraulic control system were formed,which can meet the requirements of lightweight equipment for the development of marine gas hydrate,sec-ondary icing and plugging intervention of hydrate,downhole operation condition monitoring and remote control.The research results provide reference for the development of supporting equipment for long-term stable and controllable exploitation of marine gas hydrates.
Shenhu sea areamarine gas hydratedepressurization exploitationkey technologies and equip-mentsubsea christmas tree