GB534850A - Improved gas lift pumping unit for wells - Google Patents

Abstract

534,850. Liquid-raising apparatus. KNOX, G. S. June 16, 1939, No. 17667. Convention date, June 23, 1938. [Class 102(ii)] A gas lift pumping unit for oil or other wells comprises a valve 33 and port 45 for entry of the oil, a pipe 12 through which the oil is lifted to the surface, a gas pipe 14 and valve 21 having a smaller area exposed to the gas pressure than to the liquid pressure in the pipe 12 so that it opens when the ratio of the liquid to the gas pressure exceeds a pre-determined value and closes when if falls below this value A part of the upper face of the valve 21 is closed off by a metal bellows 18 filled with gas, e.g. at atmospheric pressure, if, e.g. it is desired that only a small difference of pressure in pipes 12, 14 will open but that a comparatively great difference is required for closing the valve 21, this is formed with a cylindrical extension 23, Fig. 12, coacting with a reduced bore 65 which causes a reduction, when the valve opens, of the gas pressure in the chamber 61 which acts on a portion 62 of the upper face of the valve 21. Preferably instead of or in addition to the valve 33 a spring closed oil valve 31, Fig. 3, is provided and is opened by gas from above the valve 21 passing through bores 25 into a small bellows 27 connected to a spring lifted plunger 30. When however the valve 21 opens and hence the pressure in the constricted space 24 falls the springs 32, 29 are sufficient to close the valve. The valve 31 may comprise a pilot 51, Fig. 5, which is opened first and controls a main valve 52 in the form of an annulus by causing a pressure drop. At one or more points above a packed joint 13, Fig. 1, and a port 15 which admits the compressed natural gas or air &c. supplied to the well casing 10 into the pipe 12 an auxiliary pump is provided comprising a valve 37 which is held shut by the gas pressure below it until a float 40, lifted by plug of rising oil until it engages a stop 42, is allowed to fall when the lifting gas reaches it and strikes a pin 39. When the wad of oil reaches the surface the pressure of gas above the valve 37 is reduced and the increased flow closes it. This pumping unit will operate against a back pressure, e.g. of a pressure gas trap or separator at the surface.