Air lift pump system

Disclosed is a pumping system utilizing pressurized air injected into a lift assembly submerged in oil fluids for lifting of these oil fluids from a well. The system includes a volume expansion chamber with a self-cleaning check valving assembly. The lift assembly being suspended in the well by highly efficient, corrosion resistant, production and air supply tubing. Pressurized lift air is supplied to the lift assembly through a photovoltaic solar powered programmable control device by a pressure regulated air compressor. The entire lift system being constructed of such light weight chemically resistant materials as to allow hand installation and retrieval thereby greatly improving low production well economics. The system process efficiency is such that one air supply compressor will provide lifting capacity for multiple producing wells also providing another advantage in shallow oil well economics.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a fluid moving system whereby the movement 
of such fluid is from the producing formation elevation of a shallow well 
to the earth's surface. The more specific intended application of the 
herein described invention encompasses a downhole air lift pumping 
assembly utilizing pressurized air supplied by an air compressor through a 
photo-voltaic programmable control system which supplies artificial lift 
air to oil from its sub-surface formation through production tubing 
suspended in a well bore and casing to the earth's surface and storage. 
2. Background Art 
Many shallow oil wells do not initially contain sufficient reservoir 
pressure necessary to provide natural lift of the oil and any associated 
fluids from the sub-surface producing formation level to the earth's 
surface. When this condition exists, it becomes necessary to utilize 
equipment and methods known as "artificial lift" to accomplish movement of 
the oil fluids from the well to the surface. 
The type of pumping method selected for this artificial lift is determined 
by differing factors such as: production rate, well depth, well 
cleanliness, oil viscosity, economics of production, and others. 
The most common lift method utilized today is the reciprocating sucker-rod 
and jack technique which incorporates a piston/ball mechanical pump 
located in production tubing at the producing formation level. 
Other types of lift systems sometimes used are the submersible and screw 
type pump located downhole in the well bore; gas lift valves on production 
tubing; and the bailer or wick type pump. 
Each of these systems has its specific technique of employing lift; however 
all have common disadvantages in operation and well economics. Each 
system, excluding gas lift valves, produces friction losses and internal 
wear. Gas lift valves on the other hand, require higher reservoir pressure 
for proper operation which most shallow wells commonly lack. All of the 
above systems require high capital expenses upon initial installation due 
in part to the system design and mechanical equipment required for 
operation. They historically also require large amounts of professional 
workover maintenance expense simply to keep in operation. 
Giving consideration to the characteristics associated with these various 
pumping systems, it becomes unfeasible to drill, complete, and then 
produce many low volume shallow oil wells primarily due to the previously 
mentioned economic expenditures of equipping such a well and then the 
associated excessive mechanical expenses required to maintain it in 
operation. 
In view of this, there would be a significant advantage to shallow oil 
operations if an efficient, economical, easily installed and maintenance 
reduced lift system could be provided. 
BRIEF SUMMARY OF THE INVENTION 
The preferred form of the present invention consists of a dual-valved lift 
assembly with volume expansion chamber utilizing injected pressurized 
supply air to lift oil from the producing formation level through a highly 
efficient production line to the well surface of storage. 
The lifting of the oil is accomplished by injecting pressurized air 
supplied from a surface mounted pressure regulated air compressor through 
a programmable photovoltaic control device. The control device is 
connected to an air lift supply line extending from the control device at 
the well surface to the lift assembly downhole. Upon operation of the 
control device air is injected into the lift assembly through the inlet 
nozzle. The pressurized air then expands, decreasing the specific gravity 
of the accumulated volume of oil in the volume expansion chamber. Through 
the simultaneous action of kinetic air expansion, decreased specific 
gravity, and hydrostatic well fluid pressure, an efficient lift of oil is 
made from the downhole lift assembly to the well surface and storage. 
An important feature is the use of a photovoltaic timing circuit and pulse 
valve so programmed to match the fluid inflow rate of an individual well. 
After a pre-determined hydrostatic recharge time of the air lift assembly 
has elapsed, another lift cycle is initiated. This action then continues 
as the normal operating process of the present invention. The pressure 
regulated air compressor constantly maintains the correct operating 
pressure and supply air. The only adjustments necessary may be the 
re-programming of the control device to match any change in an individual 
well's production rate. 
It is a primary object of the present invention to provide a new and 
improved artificial lift system for shallow oil wells. This present 
invention provides a high degree of reliabilty in operation by employing 
in design a minimal number of moving parts in the downhole lift assembly 
thereby resulting in decreased maintenance expense. 
It is another object of this invention to utilize the kinetic expansion of 
pressurized air thereby decreasing the specific gravity of the contained 
oil fluids while acting in conjunction with the hydrostatic pressure head 
of the well fluids. This action provides a highly efficient air lift oil 
fluid pump system. 
It is another object of this invention to provide a single nozzle injection 
point into a closed loop lift system and by so doing eliminates any 
unnecessary pressurizing of the oil producing formation which may inhibit 
the natural inflow of oil fluids to the well bore. 
It is another object of this invention to provide an injection nozzle so 
positioned as to utilize the injected pressurized air as an internal 
cleaning medium of the assembly lift check valve making this system highly 
conducive for use in well with a high contaminant level, particularly 
formation sand. 
It is another object of this invention to provide a downhole volume 
expansion chamber used to decrease oil fluids specific gravity and 
increase lift efficiency. 
It is another object of this invention to provide a new and improved, 
lightweight, high pressure lift production and air supply tubing which as 
utilized will decrease installation and workover expenses. 
It is another object of this invention to provide a new and improved lift 
production tubing which incorporates materials with characteristics that 
exhibit maximum flow characteristics and line efficiency while maintaining 
minimal internal contaminant buildup. 
It is another object of this invention to provide a photovoltaic solar 
powered control system that in its self-contained arrangement minimizes 
installation time and expense. 
It is another object of this invention to provide a programmable control 
system capable of being programmed to match well production rates and best 
operating efficiency. 
It is another object of this invention to provide a pulse operated control 
valve which requires minimal energy consumption during operation and 
through the additional low flow characteristics of the valve minimizes 
potential emulsions which frequently form with other types of artificial 
lift systems. 
It is another object of this invention to provide a highly efficient lift 
system which utilizes a low volume of injected air thereby reducing 
operating costs. 
It is another object of this invention to provide a pressure monitoring 
device which will continuously monitor lift efficiency, well downhole 
conditions, and well fluid levels. 
It is another object of this invention to provide a surface mounted, 
pressure regulated air compressor of adequate size which will act as a 
common pressurized air supply source for multiple wells and thereby 
greatly reducing the capital cost of equipping each producing well. 
Other objects, features, and advantages of this invention will become 
apparent from the following detailed description of the specifications, 
drawings, and claims.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
FIG. 1 illustrates a typically completed oil well and general arrangement 
of the present invention. A well casing 1 extends through a well bore in 
the earth 2 to the oil bearing formation 3. The casing 1 has been cemented 
into place with cement 4. Perforations 5 are made in the casing 1 to allow 
oil fluids 6 to communicate with and flow into the casing 1 from the oil 
bearing formation 3 for removal. It should be noted the preceeding 
description of FIG. 1 details a typically completed oil well which in this 
specification has no significant bearing of the operation of the present 
invention other than to exhibit the present invention installed in a 
typically completed well. The present invention is applicable to any 
variety of well completions which consist of an open casing to the oil 
formation such as exhibited in FIG. 1. The only feature considered as 
significant is casing 1 must be of sufficient internal diameter allowing 
physical insertion of that portion of the present invention as shown in 
the enlarged perspective view of FIG. 2, the downhole lift assembly, also 
generally shown in FIG. 1 as 7. 
The oil fluids 6 entering the casing 1 will seek some natural fluid level 
6A as shown. The present invention is installed with its downhole lift 
assembly, generally shown as 7 in FIG. 1, submerged in the fluids 6 near 
or opposite the elevation of the oil bearing formation 3. The downhole 
lift assembly generally shown as 7 in FIG. 1, is connected to the 
production tubing 8 and air lift supply line 9. Production tubing 8 
supports the lift assembly through well seal 13 by tubing clamp 14. The 
production tubing 8 and air lift supply line 9 are specified as new and 
improved lightweight, pressure, chemical, and flow efficient materials. 
The conventional iron base materials customarily used in oil well 
completions and production typically reflect the materials which were 
available to the oil industry. The advent of new technology in piping 
materials now allows for a greater diversity in production techniques in 
which various materials can be successfully utilized. This present 
invention incorporates these technologically advanced materials and in so 
doing, greatly reduces installation time, expense, and associated workover 
expenses normally incurred with a standard completion. 
Production tubing 8 and air lift supply line 9 are installed in the well 
from rolls of extruded tubing of sufficient length to reach the desired 
operating level. Although the material utilized in the present invention 
should not be confined to the following, for clarity in this descriptive 
specification, the material will be designated as high molecular density, 
chemically inhibited, polyethelene tubing. 
Utilizing this unique material as production tubing 8 offers several 
advantages. A primary advantage is that for shallow well installation, the 
weight of this material is of such a value as to allow the installation of 
the entire air lift assembly generally shown as 7, production tubing 8, 
and air lift supply line 9 by hand thereby requiring no expensive workover 
rig time. 
In a similar manner, if remedial work is required to clean a well, the 
entire system is also retrievable by hand again offering a cost savings. 
The consideration of these workover expenses are of paramount concern to 
the shallow oil operator. This due in part to the general low productivity 
of these shallow wells versus the high expense of workovers. 
This material utilized in the present invention as production tubing 8 and 
air lift supply line 9 is not only lightweight and strong but is also 
chemically resistant to the corrosive and oxidizing conditions prevalent 
in many wells causing serious attack to conventional iron base materials. 
The extrusion process used in the manufacturing of this tubing also 
provides additional advantages. First, the manufacturing extrusion process 
provides a tubing in which the internal walls have an extremely low 
frictional flow coefficient (Reynolds Number) which in turn greatly 
increases the efficiency of lifting fluids. Secondly, this same internal 
characteristic also provides resistance to buildup on the internal 
surfaces of the tubing of such contaminants as paraffin and scale which 
also improves lift efficiency. Thirdly, wall wetting and fluid fall back 
are greatly reduced by the characteristic of this extrusion process. 
The flexibility of this tubing also allows the formation of flow loop 12 at 
the well casing head. This flow loop design dramatically reduces outlet 
flow losses which are normally incurred when using the standard pipe 
fittings ells and tees of a typical completion. 
FIG. 1 illustrates the lift assembly shown as 7, production tubing 8, and 
air lift supply line 9 installed in a typically completed well. Airlift 
supply line 9 is connected to the photovoltaic solar powered control 
device generally shown as 11 in FIG. 1. The control device is continuously 
supplied with pressurized air from a pressure regulated air compressor 10 
through connecting air supply line 10A providing motive force for the 
lifting operation. 
Using the general well illustration of FIG. 1 and the detailed section of 
FIG. 4, the present invention operational process can be further 
described. 
The downhole lift assembly generally shown as 7 in FIG. 1 and detailed 
further in FIG. 4, consists of several parts. Foot check valve 17 with 
stainless steel strainer 18 and stainless steel poppet 20 is constructed 
of Navy Brass. This foot check valve 17 is connected by means of a 
polyvinylchloride pipe nipple 19 in series to Navy Brass lift check valve 
16 also with a stainless steel poppet 21. This flow check assembly is then 
connected to a polyvinylchloride volume expansion chamber 15 having two 
tapped insert bushings 25 for bottom connection with the lower flow check 
valve assembly by polyvinylchloride nipple 19 and upper connection with 
production tubing 8 by polyvinylchloride insert fitting 24 and stainless 
steel clamp 14. Lift check valve 16 is tapped on the outlet side for the 
connection of brass inlet nozzle 22 and airlift supply line 9 by an acetal 
copolymer compression collet. 
For convenience in installation, air lift supply line 9 is secured to 
volume expansion chamber 15 by means of a nylon tiewrap 23 and can be 
likewise secured along the length of the production tubing 8 as needed. 
All components of polyethelene, polyvinylchloride, acetal copolymer, 
nylon, Navy brass, and stainless steel comprising this protion of the 
present invention are highly resistant to oxidation, corrosion, and 
chemical attack prevalent in shallow oil well conditions. 
With the downhole assembly of the present invention in place, the oil 
fluids 6 inflowing through perforations 5 into casing 1 have reached some 
natural level 6A as shown in FIG. 1. In the static or "off" cycle of the 
process, this level 6A produces a hydrostatic pressure head on the 
generally shown lift assemby 7 of FIG. 1. Referring to FIG. 4, this 
pressure head forces open poppet assembly 20 of the lower foot check valve 
17 allowing oil fluids 6 to pass through poppet 21 of lift check valve 16 
thereby filling volume expansion chamber 15 and production tubing 8 to an 
equalized level with fluid level 6A. The entering fluids 6 of FIG. 1 are 
maintained contaminant free by the stainless steel strainer assembly 18 of 
lower foot check valve 17 in FIG. 4. This filtering process insures a 
reduction of major particulate which might present pluggage problems of 
the lower lift check valve poppet assembly 21. If in the event small 
particulate contaminates inadvertently accumulate under the poppet 
assembly 21, inlet nozzle 22 has been so positioned that the pressurized 
injection air will clean away these contaminants. This feature results in 
a system operation with reduced maintenance problems due to contaminants 
and the accompanying pump inoperation. 
With the system equalized and prepared for the "on" lifting cycle of 
operation, control device, generally shown as 11 in FIG. 1, utilizes logic 
panel 27 in FIG. 6, to pulse open control valve 26 shown in FIG. 6 
allowing pressurized air from air compressor 10 and air supply line 10A 
shown in FIG. 1, to flow through control valve 26 of FIG. 6, monitoring 
gage assembly 28, airlift supply line 9, inlet nozzle 22 of FIG. 4 into 
lift check valve 16. 
Pressurization of the fluid column forces poppet 21 closed against its seat 
and directs the injected air into volume expansion chamber 15. This volume 
injection of pressurized air results in a kinetic release of energy 
through expansion which in turn forms a high pressure liquid-air mixing 
phase in the volume chamber 15 with such phase causing a reduction of the 
specific gravity of the oil fluids 6 contained therein. This decrease in 
specific gravity or "lightening" of the fluid 6 and associated pressure 
results in the lift cycle. The lift cycle then results in the movement of 
oil fluids 6 from the zone of higher pressure towards the zone of lower 
pressure and atmosphere at the earth's surface and storage. 
After the predetermined "on" cycle time has elapsed, the control valve 26 
in FIG. 6 is pulsed off by the programmable logic panel 27 allowing an 
"off" cycle time during which static conditions exist for the refilling of 
the downhole lift assembly generally shown as 7 in FIG. 1 in preparation 
for another lift "on" cycle. 
The production cycling rate of "on" time and "off" time can be monitored 
and appropriate programming of logic panel 27 can be determined by 
monitoring gage assembly 28 shown in FIG. 6 as follows. The fluid level 6A 
of FIG. 1 will produce a resultant back pressure head on the lift assembly 
generally shown as 7 in FIG. 1. This pressure will result in a readout on 
the pressure gage of assembly 28 when the system is in the static or "off" 
condition. Monitoring of the resultant fluid level 6A of FIG. 1 during 
operation and programming of logic panel 27 of FIG. 6 to match desired 
fluid level conditions will then result in the proper operation of the 
present invention for an individual well inflow rate. 
An additional feature of the present invention is the control device 
generally shown as 11 in FIG. 1 is a photovoltaic solar energy panel with 
a self-contained power supply and battery backup unit. The design of the 
system allows the photovoltaic solar panel 30 of FIG. 6 to charge and 
maintain an adequate power reserve in battery 29 which will maintain 
operation of the system during darkness and in the event of overcast 
conditions, can continuously operate the system for an estimated 30 days 
through the power reserve provided. This unique design feature eliminates 
the time, expense, materials, and potential dangers existing with 
conventional high voltage alternating current power source installations. 
The advantages of this feature are numerous when considering rodent, 
moisture, and unauthorized trespass of personnel in a low security field 
operation. 
A significant economic feature of the present invention is the low volume 
of supply air required to perform a lift cycle. Testing reveals a low flow 
of 3-5 cubic feet per minute during an "on" cycle of 20-40 seconds will 
provide adequate lifting of fluids. If a low producing shallow well 
requires only 15-20 cyclic operations per day, it is easily seen that the 
initial investment in one compressor of adequate size (say, 20 cfm 
capacity) can supply many wells in the same field. Typical designs 
indicate one compressor may be sized to provide lifting motive force for 
as many as 30 wells or more in the same field operation. This design of 
the present invention thereby eliminates the major equipment expense such 
as normally experienced with a jack type pumping system. The capital costs 
per well are greatly reduced due to this factor. 
The foregoing description of the present invention has been directed to a 
particular preferred embodiment for the purpose of illustration and 
explanation. It will be apparent, however, to those skilled in this art 
that modifications and changes or additions to the illustrated system and 
process taught may be made without departing from the spirit of the 
invention. It is the applicant's intention in the following claims to 
cover all equivalent modifications and variations as fall within the scope 
of the invention.