WO2005108743A1

WO2005108743A1 - Method and apparatus to remove liquids from a well

Info

Publication number: WO2005108743A1
Application number: PCT/US2005/015081
Authority: WO
Inventors: David Randolph Smith
Original assignee: The Research Factory, L.C.
Priority date: 2004-04-30
Filing date: 2005-05-02
Publication date: 2005-11-17

Abstract

The present invention includes methods and apparatuses to pump fluids from a depth of a wellbore. The methods and apparatuses preferably use a hydraulically actuated reciprocating pump (fig 1) to pump fluids from the subterranean depths of a wellbore to the surface.

Description

METHOD AND APPARATUS TO REMOVE LIQUIDS FROM A WELL

BACKGROUND OF THE INVENTION The present invention relates to a hydraulically operated pump apparatus and method. More particularly, the present invention relates to a hydraulically operated pump for downhole use. More particularly still, the present invention relates to a hydraulically operated pump to pump fluids from a downhole location to a surface location. In various downhole operations, it is often necessary to pump fluids from a downhole location to the surface. This can include the pumping of water, production fluids, or any other fluid needed to be removed. Because of the tight confines of wellbores, it is often not feasible to deploy traditional pumping apparatuses to their subterranean depths. Prior artificial lift systems have employed downhole pumps that are actuated by a reciprocating rod. The rod typically extends to the surface where a motor assembly reciprocates the rod, thereby oscillating the downhole pump and bringing the fluids to the surface. While effective, systems of this type usually require the permanent installation of a motor assembly (one having structural support) and the manufacture of a long lift rod to extend down the hole to the subterranean pump. A system capable of being easily and temporarily disposed within the wellbore therefore is highly desirable. BRIEF SUMMARY OF THE INVENTION

The present invention discloses a hydraulically operated pump

assembly and method for controlling a hydraulic pump. The pump is

preferably configured to be actuated by first and second hydraulic power

transmission line to oscillate a downhole piston, configured within a cylinder,

to move from a first upward position to a second downward position. The piston in the cylinder separates a first fluid chamber and a second fluid

chamber and is urged into the downward position when pressure within the

first power transmission line is increased; while said piston is urged into the

second upward position when pressure within said second power transmission

line is increased. A fluid return line connects the outlets of said first and

second fluid chambers to allow the movement of fluid from the pump to the

surface. Pressure within the first and the second power transmission lines

can be controlled by a surface pump, which alternatively can be powered by

solar energy. The first and said second power transmission lines and the fluid

return line can extend through a hydraulic packoff isolating the wellbore from

the atmosphere. Gas can be produced from the wellbore simultaneously with

the production of fluids through the fluid return line in those wells which still

flow gas or in which gas production increases when fluid is taken from the

well. The first and said second power transmission lines can extend down the

wellbore in a parallel arrangement or can be deployed in a coaxial

arrangement. The working fluid used within the first and second power

transmission lines can be the same as the fluids produced through said fluid

return line thereby replenishing the supply from the produced fluid. The first

power transmission line can provide an injection valve to allow the bleeding of

gas from the first power transmission line and the injection of a chemical

substance therethrough. The second power transmission line can include an

injection valve to allow the bleeding of gas from the second power

transmission line and the injection of a chemical substance therethrough. The apparatus described can be used to produce fluids from a wellbore,

in the following manner. An operator would install a hydraulically actuated

pump to a desired depth within the wellbore; commence operating the

hydraulically actuated pump with a surface power pump, wherein the surface

power pump pressurizes power transmission lines extending from the sur ace

of the wellbore to the depth within the wellbore. This would cause a

reciprocating of a piston within the hydraulically actuated pump with a surface

control system, the surface control system configured to alternate pressure to

the power transmission lines to oscillate the piston from a first position to a

second position; and to thereby pump the fluids from the wellbore up a fluid

return line when the piston is oscillated between the first and the second

position. The operator could also inject chemicals to the desired depth

through an injection valve located within the power transmission lines. The

operator in certain circumstances could bleed gas from the power

transmission lines through an injection valve mounted thereupon.

The novel apparatus and method of the present invention are more fully described in the drawings and detailed description herein.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS Figure 1 is a schematic sketch of a hydraulically actuated downhole pump assembly in accordance with a preferred embodiment of the present invention. Figure 2 is a schematic sketch of a hydraulically actuated downhole pump assembly and surface control scheme in accordance with a preferred embodiment of the present invention. Figure 3 shows a schematic sketch of a valving diagram of a pumping method and apparatus for a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION To recover production fluids, a well is drilled, cased, and cemented. The casing is then preferably connected to a wellhead valving system and the well is preferably perforated at a depth to produce fluids. A preferred embodiment of the present invention preferably includes deploying a pump assembly through the cemented casing or production tubing. The pump assembly preferably includes a system having three hydraulic lines with a hydraulically actuated pumped disposed thereupon. Two of the hydraulic lines preferably transmit hydraulic power to the pump and the third hydraulic line preferably carries the fluids to be produced and discharged from the wellbore. Preferably, fluids are produced through the production line on both strokes (up and down) of the hydraulic pump, but a separate line for each stroke may be desired and used instead. Preferably, the production hydraulic line includes a standing valve or check valve in it to keep fluids from "falling" back down the hydraulic line and returning back to the pump assembly downhole after discharge. Referring initially to Figure 1, a schematic hydraulic pump assembly 100 is shown. Pump assembly 100 preferably includes three hydraulic lines, L1 , L2, and L3. L1 is shown as a hydraulic down-stroke operation line, L2 is shown as a hydraulic up-stroke operation line, and L3 is shown as a production fluid return line. While the lines are shown as three distinct lines, it should be understood by one of ordinary skill in the art that lines L1 , L2, and L3 may be constructed as a single coaxial line having three distinct fluid flow passages. Pump assembly 100 includes a hydraulic piston assembly P that reciprocates up and down within a housing of pump assembly 100. Piston P defines two pumping chambers 1 and 2, and two pressure actuation surfaces U and D. Chambers 1 and 2 can be segregated by providing elastomeric seals S1 between the piston P and the inner wall of the vessel as is common in the industry. Pressure from line L1 engages surface D and drives piston P down. As piston P is driven down, chamber 1 fills with production fluids through inlet valve 11 and production fluids within chamber 2 are forced through outlet valve 02 to line L3. Next, pressure from line L2 engages surface U and drives piston P upward. As piston P is driven upward, chamber 2 fills with production fluids through inlet valve 12 and production fluids within chamber 1 are forced through outlet valve 01 to line L3. The upward and downward movement of piston P is alternated at a desired frequency to allow production fluids to flow from the wellbore, through line L3, and up to the surface. Valves, 11 , 12, 01 , and 02 are preferably one-way check valves that only allow flow of production fluids in a single direction. Injection valves IV1 , IV2 allow for elevated pressures within lines L1 , L2 respectively to be released therefrom. Once the apparatus is in location, the hydraulic lines L1, L2 are connected to a surface hydraulic power system that includes a series of valves and a surface pump. Referring briefly to Figure 2, a schematic of the surface hydraulic power system can be described. To operate the pump, fluids are preferably pumped down line L1 with all valves closed except for valve V1. This forces fluid out of injection valve IV1 to purge line L1. This step is capable of removing air bubbles or gas from line L1. Next, valve V1 is closed and valve V2 opened and air is similarly bled through injection valve IV2 to purge line L2. Next the surface pressure required for the surface pump to operate piston P is preferably set on the surface control logic such that the operating pressure to function the downhole pump is less than the pressure required to open injection valves IV1 , and IV2. In addition to their use in purging lines L1 and L2 from air or gas bubbles, injection valves IV1 and IV2 can also be used as chemical injection ports for wells that require the addition of chemicals downhole. Next, by switching the surface valves in an appropriate sequence, the surface pump oscillates piston P upward and downward to deliver fluids from the wellbore up line L3; the fluids can be delivered to a storage tank T1 , for example, or to an alternate location for storage and/or use. The surface power system provides the switching and logic for activating the downhole pump assembly 100. The surface power system powers, the downhole pump assembly 100. ^! Using the apparatus and method as described, gas fluids are capable of being simultaneously produced from a well with gas production. Using a three-line wellhead packoff, fluid pressure (gas or liquid) can be maintained with lines L1 , L2, and L3 extending therefrom and continuing to operate downhole pump 100. The weight of hydrostatic pressure within lines L1 and L2 allow minimal power input from the surface pump to operate piston P of downhole pump 100. Furthermore, lines L1, L2, and L3 can be manufactured of continuous hydraulic line (or hose), or jointed sections of line or pipe, depending on preferences of the well operator. Referring to Figure 3, a method of operating a downhole pump like the one disclosed in Figures 1-2 can be described. The method preferably includes opening line L1 and valves V1 and V4 and closing valves V2 and V3. Next, when pressure within line L1 reaches a set pressure, line L1 is vented to a pump reservoir tank T2 via valve V3. Next, valves V1 , V3, and V4 are closed, valve V2 is opened and fluid is pumped down line L2. When L1 reaches the set pressure, L2 is vented via valve V4 to the pump reservoir T2. When pumping down line L1 , alves V4 and V1 are opened by the surface controller and valves V2, V3, and V5 are closed. When pressure in line L1 reaches the set pressure, valve V4 is closed, valve V5 is opened, and valve V1 is closed. Next, valve V5 is closed, valve V3 is opened, and valve V2 is opened. When pumping down line L2, valves V3 and V2 are open and valves V1 , V4, and V5 are closed. When pressure in line L2 reaches the set pressure, valve V3 is closed, valve V5 is opened, and valve V2 is then closed. Next, valve V5 is closed, valve V4 is opened and valve V1 is opened. The process is then repeated, preferably with computer control of valves V1 , V2, V3, V4, and V5 to maximize the speed of operation of downhole pump 100. Optionally, the system can include the use of a gas operated surface pump using the well pressure for power as part of the system. The system can include powering the surface pump with chemical energy from gas. The system can include powering the surface pump with solar power. The lines in the system can extend downhole in parallel or concentrically. The system can include running multiple fluid conduits to transmit the power fluid and a separate fluid conduit to transmit the produced fluids to the surface. The system can include timing and switching the hydraulic power fluid at the surface between the hydraulic power conduits running from surface to the depth of the well. The system can include having a downhole injection valve built into each of the hydraulic control lines down at the bottom end in the well to be opened by applying sufficiently high pressure to open them and allow fluid to discharge into the well therethrough. The system can include the hydraulic power fluid being the same as the produced fluid. The system can include the power fluid as a separate fluid from the produced fluid, for example, a fluid with lubricating qualities. The system can include a power fluid having corrosion inhibitors, scale inhibitors, hydrate inhibitors, paraffin inhibitors, and wax inhibitors. The piston of the downhole pump of the system can optionally be biased with springs. In another embodiment, line L1 can be filled with a heavy fluid, such as brine. Line L2 can be filled with a lighter fluid, such as an oil. The weight of the brine over the length/heighth of L1 can effectuate the pumping motion of the piston in the downward direction. A flow scheme such as this could decrease capital and/or operating expenses when installing and operating the downhole pump of the present invention. One skilled in the art will realize that the embodiments disclosed are illustrative only and that the scope and content of the invention is to be determined by the scope of the claims attached hereto.

Claims

CLAIMSWhat is claimed is:

1. A downhole pump to remove fluids from a wellbore, the pump comprising: a first power transmission line and a second power transmission line; a piston, said piston configured to be displaced within a cylinder from a first upward position to a second downward position; said piston within said housing defining a first fluid chamber and a second fluid chamber said piston urged into said first downward position when pressure within said first power transmission line is increased; said piston urged into said second upward position when pressure within said second power transmission line is increased; and a fluid return line connected to outlets of said first and second fluid chambers.

2. The downhole pump of claim 1 wherein pressure within said first and

said second power transmission lines are controlled by a surface pump.

3. The downhole pump of claim 2 wherein said surface pump is powered

by solar energy.

4. The downhole pump of claim 1 wherein said first and said second

power transmission lines and said fluid return line extend through a hydraulic

packoff isolating the wellbore from the atmosphere.

5. The downhole pump of claim 4 wherein gas is produced from the

wellbore simultaneously with the production of fluids through the fluid return

line.

6. The downhole pump of claim 1 wherein said first and said second

power transmission lines extend down the wellbore in a parallel arrangement.

7. The downhole pump of claim 1 wherein said first and said second

power transmission lines extend down the wellbore in a coaxial arrangement.

8. The downhole pump of claim 1 wherein a working fluid used within said

first and said second power transmission lines is the same as the fluids

produced through said fluid return line.

9. The downhole pump of claim 1 wherein said first power transmission

line includes an injection valve, wherein said injection valve is configured to

allow the bleeding of gas from the first power transmission line and the

injection of a chemical substance therethrough.

10. The downhole pump of claim 1 wherein said second power transmission

line includes an injection valve, wherein said injection valve is configured to

allow the bleeding of gas from the second power transmission line and the

injection of a chemical substance therethrough.

11. A method to produce fluids from a wellbore, the method comprising: installing a hydraulically actuated pump to a desired depth within the wellbore; operating the hydraulically actuated pump with a surface power pump, wherein the surface power pump pressurizes power transmission lines extending from the surface of the wellbore to the depth within the wellbore; reciprocating a piston within the hydraulically actuated pump with a surface control system, the surface control system configured to alternate pressure to the power transmission lines to oscillate the piston from a first position to a second position; and pumping the fluids from the wellbore up a fluid return line when the piston is oscillated between the first and the second position.

12. The method of claim 11 further comprising injecting chemicals to the

desired depth through an injection valve located within the power transmission

lines.

13. The method of claim 11 further comprising bleeding gas from the power

transmission lines through an injection valve mounted thereupon.