Patent ID: 6213201
Filing Date: 2001-04-10
Classification: E21B

Abstract:
A low pressure system of gas production and liquid removal from gas wells employing a large volume expansion tank, where the well is constructed to contain an open ended internal tubing string, the open, lower end is set at the level of gas producing zones, within a larger external casing, that is cemented into the gas producing formations, and subsequently perforated at the said formations to feed gas from the gas producing zones into an annulus, the space between the larger casing and the smaller tubing; said tubing is open ended to allow free passage of gas and fluid from the annulus into this tubing; the down hole end consists of a retainer, a bottom hole spring, and a steel plunger that is loosely fitted within the tubing string, wherein at a predetermined pressure differential, the tubing valve opens automatically, allowing the plunger's travel upwards, and bring the collected well liquids towards the surface, said liquids and the gas accumulation ahead of the liquids are allowed to discharge to an expansion tank, eliminating the restricted volume, conventional gas separator, designed to accept the volume of gas and well fluids from at least one well clean out cycle, at a reduced pressure, to be subsequently fed into a gas sales line at a controlled pressure; by means of a fully automatic gas well production control system, identified as a, simplified control mechanism means for discharging gas and liquid from the gas well; said means to include two switch gauges to sense the annular and tubing pressure, that are preset to form an electrical circuit when a predetermined pressure differential is reached between the tubing and the annulus, and upon the exhaustion of the gas from the expansion tank to the sales line; said electric circuit means to be energized by means of AC or DC power to operate two time delay relays that are interdependent upon each other to operate one electromagnetic solenoid slave valve, also powered by the same power source, that, upon activation, will open a normally closed fluid and gas discharge line, and close a normally open gas production line from the tubing string, to avoid the discharge of fluid into the gas sales line during the clean out cycle; said discharge and gas production pressure operated line valves, as well as the slave valve to be powered by means of a regulated supply pressure, sourced from the constant, dry and stable gas pressure of the annulus; said valve operation control to be accomplished by the completed switch gauge control circuit means of the first relay that is further controlled by, and dependent upon, the second relay means that maintains a closed electrical circuit to the electromagnetic solenoid slave valve, until a signal from a magnetic sensor, that opens the electric circuit upon the arrival of the steel plunger, at the proximity of the sensor at the top of the tubing string; said first relay means to initiate the gas discharge, and the well clean out cycle, is preset with sufficient time delay to allow the complete exhaustion of the arriving tubing fluid content initiated by the cycle; the cycle is terminated by the preset function of the second relay; said second relay means maintains a closed electrical circuit, until it is deactivated by the means of the steel plunger to sensor magnetic field signal, that acts as the external switch for the second relay; this momentary disruption opens the electric circuit to the solenoid slave valve, thereby closes the valve to the fluid discharge line, reopens the gas production line, and coincidentally, resets the simplified control mechanism for the next well clean out cycle; the accumulated waste fluids collected in the expansion tank to be subsequently transferred by manual or automatic means to a fluid holding tank for disposal.