Ventless gas-driven pumping system

Abstract

A ventless gas-driven pumping system controlled via a plurality of pneumatic valves and associated switches, for driving a diversity of process pumps at a natural gas well site. The ventless pumping system is readily interconnected with any gas pipeline location and uses flowing well gas and consequent differential pressure to drive a plurality of pumps and related pneumatic controls exclusively using a continuous self-generated air supply. Only self-generated air and no well gas is vented into the atmosphere during pumping operations.

1 . A ventless pumping system for operating a plurality of process pumps with said: ventless pumping system interconnected with a flowline having well gas flow therein, said ventless pumping system comprising:
 a differential pressure control valve member connected into said flowline to generate a pressure differential between an inlet member and an outlet member, with said well gas flow through said inlet member flowing at higher pressure than said well gas flow at said outlet member;   a cycling valve member for continuously directing said high pressure well gas alternately to each side of a drive cylinder member and for simultaneously directing said lower pressure well gas alternatively to each opposite side of said drive cylinder member, while recycling said lower pressure well gas to said flowline without any venting thereof into the atmosphere;   said recycling valve member alternately redirecting said high pressure well gas to either side of said drive cylinder member;   said high pressure well gas supplied through said cycling valve member to said drive cylinder member for mechanically actuating, in turn, each of a pair of switching valve members;   each switching valve member of said pair of switching valve members disposed at an opposite end of said drive cylinder member adjacent a sealed drive piston rod of a pair of sealed drive piston rod members, with each said sealed drive piston rod member extending outwardly from a corresponding end of said drive cylinder member;   a piston member disposed annularly of said drive cylinder member and axially containing said pair of sealed drive cylinder piston rod members;   said pair of sealed drive cylinder piston rod members driving an interconnected air cylinder member for self-generating low pressure air to actuate said pair of switching valve members and said cycling valve member; and   said plurality of process pumps interconnected with said pair of sealed drive cylinder piston rod members and being powered thereby.   
   
   
       2 . The ventless pumping system recited in  claim 1 , wherein a shuttle valve member receives a small startup amount of said well gas at low pressure from a gas regulator member interconnected with said flowline and supplies said small startup amount thereof to air lines interconnected with and operating said pair of switching valve members and said cycling valve member for a short time until stroking of said drive cylinder piston member commences. 
   
   
       3 . The ventless pumping system recited in  claim 2 , wherein said shuttle valve deactivates said well gas flow from said gas regulator member once said self-generated air supply pressure exceeds said pressure of said well gas flow from said gas regulator member, wherein said self-generated air supply commences controlling said pair of switching valve members and said cycling valve member. 
   
   
       4 . The ventless pumping system recited in  claim 1 , wherein said self-generated low pressure air is received by an air bottle member and said interconnected air lines, with an adjustable vent valve member sustaining said low pressure in said air bottle and said interconnected air lines by venting any excess of said self-generated air into the atmosphere. 
   
   
       5 . The ventless pumping system recited in  claim 4 , wherein said self-generated low pressure air is directed to an air-actuated cylinder disposed at an end of said cycling valve member by said switching valve member and urges said cycling valve member to cycle from a first position to a second position and then venting said low pressure self-generated air into the atmosphere. 
   
   
       6 . The ventless pumping system recited in  claim 5 , wherein said self-generated low pressure air flow and said pair of switching valve members cause said cycling valve member to continuously cycle from said first position to said second position, and vice versa, to sustain said driving of said drive cylinder member and, in turn, to sustain said driving of said plurality of process pumps. 
   
   
       7 . The ventless pumping system recited in  claim 1 , wherein said drive cylinder member comprises a piston member disposed annularly thereof and with each of said pair of switching valve members interconnected at an opposite end thereof. 
   
   
       8 . The ventless pumping system recited in  claim 7 , wherein one of said pair of said switching valve members is urged by said adjacent sealed drive cylinder piston rod member and said switching valve member actuates said cycling valve, directing said high pressure well gas to a first end of said drive cylinder member, and simultaneously directing said lower pressure well gas to a second, opposite end thereof, and upon completing its stroke, said other sealed piston rod member mechanically actuating said adjacent switching valve member which, in turn, actuates said cycling valve member for redirecting said high pressure well gas to said second end of said drive cylinder member and simultaneously redirecting said lower pressure well gas to said first end thereof. 
   
   
       9 . The ventless pumping system recited in  claim 8 , wherein simultaneously with said piston member actuating said cycling valve member, expelling said well gas at lower pressure from the other, opposite end of said drive cylinder member to said well gas outlet and back into said flowline. 
   
   
       10 . The ventless pumping system recited in  claim 1 , wherein at least one process pump of said plurality of process pumps includes a low discharge pressure switch member indicating an interruption of normal, adequate fluid discharge pressure, and a gas-operated diaphragm pump member is activated until sufficient pressure is generated to sustain normal flow of said process pump fluid. 
   
   
       11 . The ventless pumping system recited in  claim 10 , wherein said gas-operated diaphragm pump member is deactivated when said normal process pump flow has been restored.