The Design And Research Of Wellhead Safety System

Subsurface safety valve (SSV) and wellhead safety control system (WSCS) arerespectively the performing mechanism and the control section of the wellhead safety system,and impact directly its operational performance. At present the domestic research of SSV isstill in its infancy, poor sealing, complicated structure and small inner-size are all its defects.Wellhead safety control systems used currently are controlled by hydraulic and pneumatic orhydraulic only. In the long-term use, a series of problems such as inaccurate guide pressure,lack of power supply, component failure, bad sensitive properties in pressure sensorsemerged.In the reference of domestic and international successful SSV and WSCS products, withthe help of advanced FEA and CAD software, SSV that could be used under the depth of1000m was independently designed. In this design, a self balancing mechanism was added,and that provided a possible solution for the leakage of the control pipeline when it was usedin ultra deep well. The traditional plate type flapper was redesigned to the spherical type, andthis greatly reduced the space occupied by the valve plate, and provided a valve bore ofsubstantially the same size as the bore of the well tubing. The traditional cone type sealingbetween the valve plate and seat was changed to spherical type, which increased the sealingsurface, and then improved the sealing performance. By the use of FEA transient analysistheory, the procedure that the flapper plate rubbed against the operator tube was simulated.What’s more, existing wellhead control system was also improved in this article. A set of theelectro-hydraulic control wellhead safety control system was designed based on theexplosion-proof control theory. With the control circuit inserted into the wellhead safetycontrol system, and combined with the hydraulic control, hydraulic and electronic controlcircuit was designed to meet the required function. Then the various components of controlsystem were selected according to the needs of the system under the condition fully considering the antiknock performance. Finally a3D model was constructed, which showedthe layout of the control system.