WELL RIG LIFT SYSTEM AND A HYDRAULIC ENERGY-STORING WELL RIG LIFT SYSTEM

摘要

A well rig lifting system and a hydraulic energy-storing wellrig lifting system, wherein a high pressure energy-storingcylinder and a composite cylinder or cylinder group are used tocarry out the lifting and lowering operations. During thelifting operation, a power machine under a substantiallyconstant load continuously pumps oil to the energy-storingcylinder, and communication relationships of the energy-storingcylinder with various chambers of the composite cylinder orcylinder group is selected to provide an appropriate liftingforce to lift the pipe string. Therefore, the installed capacityof the power machine can be reduced to 1/3-1/4 of that in aconventional lifting system. During the lowering operation,communication relationships of the energy-storing cylinder withvarious chambers of the composite cylinder or cylinder group isselected to provide an appropriate lifting force grade less thanthe gravity of the pipe string, so as to utilize theenergy-storing cylinder to recover the potential energy releasedduring the lowering of the pipe string. The recovered energy canthen be used to carry out auxiliary operations during thelowering operation, and therefore no power machine is needed torun. The recovered energy can also be used in power generation,heating, etc.