Artificial lift for oil wells

An artificial lift apparatus for a hydrocarbon producing well having a well head and a well casing therein, said apparatus comprising:

• production tubing extending from the well head into the casing to a level below which the hydrocarbon will naturally fill from a hydrocarbon producing zone through perforations in the casing;
• accumulator means attached to the bottom of the production tubing for collecting hydrocarbon in the well;
• gas tubing means extending from the well head into the accumulator means for communication therewith from the well head;
• piston means located in said production tubing and normally positioned above said accumulator means, said piston means being free to move up and down said production tubing;
• path means communicating with said accumulator for moving hydrocarbon above said piston means when said piston means is in its normal position;
• first check valve means for only allowing flow of hydrocarbon into said accumulator means;
• control means for alternately venting and pressurizing said accumulator means via said gas tubing means, hydrocarbon being allowed to collect in said accumulator means via said first check valve means during venting, thereafter, in response to said pressurizing, said hydrocarbon is moved through said path means above said piston means in said production tubing and raised to the well head with said piston means;
• sealing means for sealing the top of said casing;
• packer means for sealing said casing above said perforations in said casing to form a tank means from the upper portion of said casing means pressurizing said tank with gas;
• said pressurized gas means being used to pressurize said accumulator means fluidly communicating said tank with the lower face of said piston means so that said piston means moves up and down in response to pressure within said tank.