FIELD OF INVENTION
This invention relates generally to gas gathering and transportation systems and, in particular, the extraction of fluid out of gas gathering and transportation pipelines.
BACKGROUND OF THE INVENTION
In gas gathering and transportation systems, fluid in pipelines has been a constant source of problems and expense. In depleted fields in particular, where wells must be pulled down to a few pounds or a vacuum to maintain production, the problem is worse. For many years the amount of vacuum was limited due to the use of compressors which leak oxygen past mechanical seals and rings. The advent of liquid ring and rotary liquid screw type compressors supplied the industry with the ability to increase production in the Panhandle West gas fields, and many other fields, by reducing the pressure below atmospheric without introducing oxygen into the system. Over the past 20 years this has led to entire fields involving thousands of wells which must be kept at various vacuums, with many at 22″, which is close to the maximum that can be reached at the elevation of the Panhandle West fields.
A method to extract fluid out of these lines has remained many years behind the technology used to place them in the existing situation. As the secondary recovery technique progressed, the time increased for wells and gathering lines to pressure up and blow the fluid out of the drips when the compressors were shut down or bypassed. (A “drip” is typically an underground vessel designed to catch and hold fluids which drop out of natural gas during transportation through pipelines). Over the past several years the situation has evolved into a major problem. Drip trucks cannot pull fluid out unless the system is vented or left down for long periods of time in order to lower the amount of vacuum. In many cases entire sections of a field involving several wells must be shut down and lines allowed to suck in air. After a point is reached where a truck can empty the drip, the wells are opened and lines purged to atmosphere to evacuate the oxygen which was sucked in.
The wasted power for compressors, the amount of gas lost with air during the purging process, and the hours of trucking cost and down time are unacceptable. The danger of environmental impact problems due to the wasted natural gas is increasing because the oxygen tends to lay in the low parts of the lines and a large amount of gas must be vented to attain the 50 ppm or less oxygen content required to enter the pipeline system and resume normal production delivery. Many of these wells will not return to positive pressure in several months or years. Even in newer wells, gas is wasted and the environment is impacted as thousands of mcf are lost daily to the atmosphere when vacuum trucks or gear type pumps are used to load the drip trucks.
One of the insurmountable problems with all prior art is the mixture of the fluid in these drips. The fluid is a high gravity condensate mixed in various degrees of percentage with water. Pumps used to move normal liquefied petroleum gas or Y-Grade products are damaged or unsuitable for moving water and heavier liquids. Pumps used to move fluids are not capable of moving the Y-Grade type hydrocarbons. Vacuum type pumps are limited to the same or less vacuum capability as the elevation of the gathering system.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is view of a closed system for pumping fluid from an underground drip. A pump barrel is in communication with a fluid collecting within the underground drip. A stuffing box helps provide for vertical adjustment of the pump barrel so that the nipple end of the pump tags a bottom of the drip. A vertically positioned elongated stroke actuator cylinder supported above the pump barrel actuates a piston in communication with the pump plunger to force fluid upward into a tee fitting and to a collection vessel.
FIG. 2 is a view of the pumping system in which a pumping tee is screwed directly to the siphon line. Valving on the pumping tee allows the drip to be sucked out or blown in a normal way if the pump is not working.
FIGS. 3A and 3B are a view of the pumping system in which a ball valve is connected above the pumping tee and the stuffing box is screwed into the ball valve. When the pump pulled, the ball valve may be closed prior to clearing the stuffing box and the pumping system does not have to be shutdown if repairs are needed.
FIGS. 4A and 4B are a view of a stuffing box-free pumping system. To ensure that the straining nipple tags the bottom of the pump, the pump barrel and piping must be cut to exact length pipe.
FIG. 5 is a view of a power source for the pumping system. On many remote locations solar power panels may be used as the power source. In addition, if a hydraulic cylinder is used as the stroke actuator cylinder, the hydraulic fluid pump system may include a hydraulic control.
SUMMARY OF THE INVENTION
A system and method for pumping fluid out of an underground drip includes a pump barrel in communication with a fluid collecting within the underground drip. The drip may have a positive pressure or may have a vacuum within. A vertically positioned elongated stroke actuator cylinder is supported above the pump barrel and in alignment therewith.
The pump barrel may be located within a portion of an existing siphon line. The system may also include a ball valve that receives the pump barrel and sealably closes access to an upper end of the siphon line. The pump barrel may also have at least one vent port and include a plunger having at least one vent hole and one or more traveling valves.
The stroke actuator cylinder may be a hydraulic cylinder, an air cylinder, a vacuum cylinder, an electric cylinder, or an electromagnetic cylinder, and includes a vertically displaceable piston that is in communication with the pump plunger. The stroke actuator cylinder may also include a seal member affixed to a lower end of the cylinder for sealably and reciprocally receiving a piston rod.
A power system powers the stroke actuator cylinder to vertically reciprocate the piston and thereby the plunger. Fluid flows upwardly under pressure through a passageway formed by the pump barrel and into a tee fitting vertical passageway and out through the tee fitting side opening to a collection vessel. The collection vessel may be a low pressure tank or a surface pressurized tank and may have a vapor return line in communication with the underground drip. The pump, stroke actuator cylinder, tee fitting, and collection vessel form a closed system. A water collection tank may also be included.
The system may include a stuffing box that allows for vertical height adjustment of the pump barrel and piping. The stuffing box is mounted on the siphon line and then the pump barrel is inserted through the siphon line until the straining nipple of the pump tags a bottom portion of the drip. Stuffing box is then tightened to seal the pump barrel to the siphon line to prevent air from entering the drip.
The method of pumping the underground drip includes the step of inserting the pump barrel into the drip until the straining nipple end of the pump barrel tags a bottom portion of the drip. The pump barrel is sealed at an upper end and the elongated stroke actuator cylinder is positioned and sealed above and in alignment with the pump barrel. A collection vessel is connected to a tee fitting in communication with the pump barrel. A plunger within the pump barrel is then sequentially vertically manipulated by the stroke actuator cylinder to pump fluid located within the underground drip to the collection vessel.
The method may also include the step of inserting and passing the pump barrel through an open ball valve attached to an upper end of a siphon line. The pump barrel may then be removed from the siphon line and the ball valve closed. A draining step may be accomplished by a tee with a valve located below the ball valve.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Elements of the preferred embodiments illustrated by the drawings and described herein are referenced by the following numbers:
Drip pumping system
Fluid outlet tee
Top of 16
Stroke actuator cylinder