Abstract
A pump for extraction of water, petroleum or other fluids from thousands of meters of depth is a reciprocating pump that reduces the incidence of piston seizures and, furthermore, gas locks that block fluid from entering the pump. When the pump is introduced into a well casing or tubing, a sleeve of the pump latches to the well casing or tubing and allows a hollow piston to travel therein in a reciprocating motion for fluid extraction. A traveling valve is located in the hollow piston and fixed valve is seated in the well casing or tubing. The sleeve length is less than the length of the hollow piston. In a preferred embodiment, passages are provided for releasing gases.
Claims
1. A reciprocating pump for extracting water, petroleum, and other fluids actuated by a pumping rod moved by a pumping apparatus, the pump being introduced within a casing of a well, the reciprocating pump comprising: a sleeve adapted for attachment to the casing; a hollow piston slidably received within the sleeve, the hollow piston having a length that is longer than a length of the sleeve; a traveling valve operably disposed in the hollow piston; and a fixed valve adapted to be seated in the casing below the traveling valve; wherein because the length of the piston is longer than the length of the sleeve, an annulus formed between the piston and the sleeve is smaller than an annulus formed over a remainder length of the piston and the casing; wherein the sleeve includes an outer wall and an inner wall, the inner wall has internal sections, each internal section increases in width in an ascending direction with regard to an adjacent internal section; each internal section includes a first portion forming a first step and a second portion forming a second step, reducing an annular space between the piston and the sleeve in the ascending direction, wherein the second portion includes horizontal passages that cross the second step and communicate with a chamber that stores gases produced by the fluid in the sleeve; wherein the horizontal passages serve to expel the gases present on the fluid to an exterior side of the sleeve.
2. The pump as claimed in claim 1, wherein the hollow piston is greater than 2.5 times the length of the sleeve.
3. The pump as claimed in claim 1, wherein the hollow piston is in a range from 2.5 times to 5 times the length of the sleeve.
4. The pump as claimed in claim 1, wherein the sleeve is a unitary structure with the casing.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The pump of the present invention will be better understood by referring to the following detailed description of preferred embodiments and the drawings referenced therein, in which:
(2) FIG. 1A is a cross section view of a well having a PRIOR ART pump for extracting oil, water and other fluids in an upstroke phase;
(3) FIG. 1B is an enlarged view of detail X of FIG. 1A;
(4) FIG. 2A is a longitudinal cross section view of a well and one embodiment of a pump according to the present invention during an upstroke phase, where an upper traveling valve is in a closed position and a lower fixed valve is in an open position;
(5) FIG. 2B is an enlarged view of detail Y of FIG. 2A;
(6) FIG. 3 is a longitudinal cross section view of the pump of FIG. 2A during a downstroke phase, where the upper traveling valve is in an open position, and the lower fixed valve is in a closed position;
(7) FIG. 4 is a longitudinal cross section view of a well and another embodiment of the pump according to the present invention, having passages for removal of gases present in the fluid being extracted;
(8) FIG. 5A is an enlarged view of detail Z1 of FIG. 4;
(9) FIG. 5B is an enlarged view of detail Z2 of FIG. 5; and
(10) FIG. 6 is an enlarge view of the pump according to the present invention showing the step formed on the inner wall of the sleeve.
DETAILED DESCRIPTION OF THE INVENTION
(11) FIGS. 1A and 1B illustrate a pump of the prior art used for petroleum extraction. A pump is introduced into a well casing 1. A rod string 2 of the pump is driven reciprocally, the rod string 2 being connected to a hollow piston 3 having a corresponding traveling valve 4. The traveling valve 4 is closed during an upstroke phase, as depicted by arrow A. The hollow piston 3 slides inside a long barrel 5. A fixed valve 6 is located at the lower extremity of the barrel 5. As shown in FIG. 1A, the length of the hollow piston 3 is significantly less than the length of the barrel 5 in which the hollow piston 3 travels.
(12) FIG. 1B, which is an enlarged view of detail X in FIG. 1A, schematically illustrates the presence of solids a, such as sand, drillings or other abrasive elements, which are drawn into the annulus 7 between the hollow piston 3 and the barrel 5, when the piston moves in an upstroke phase, depicted by arrow A. These solids a can cause the hollow piston 3 to seize or lock up against the barrel 5, as discussed above.
(13) FIGS. 2A and 2B illustrate one embodiment of a pump 10 according to the present invention that overcomes the disadvantages of the prior art pump of FIGS. 1 A and 1B. As shown in FIG. 2A, pump 10 of the present invention is illustrated in place in a well casing 1. The pump 10 has a sleeve 12 that has an inside diameter that is less than the inside diameter of the well casing 1. The pump 10 of the present invention also has a hollow piston 14 that is longer than the sleeve 12 in which the hollow piston 14 travels. The hollow piston 14 is preferably greater than 2.5 times the length of the sleeve 12, more preferably in a range from 2.5 times to 5 times the length of the sleeve 12.
(14) Although the sleeve 12 of the embodiment in FIGS. 2A and 2B is formed as a unitary structure with the casing 1, it is also possible, in another embodiment, to attach the sleeve 12 as an annular body to the casing 1. This embodiment is shown in FIGS. 3, 4, 5A and 5B. As in the prior art pumps, the hollow piston 14 has a traveling valve 16 and fixed valve 18.
(15) FIGS. 2A and 2B show, in contrast to the Prior Art in FIGS. 1 and 1B, the pump 10 in an upstroke phase, depicted by Arrow A. FIG. 2B, which is an enlarged view of detail Y in FIG. 2A, shows abrasive solids a are not drawn into the annulus 22 between the hollow piston 14 and the sleeve 12 and moreover, the action of the upstroke of the hollow piston 14, entrains in the fluid any solids a built up on the upper edge of the sleeve 12.
(16) In FIG. 3, the hollow piston 14 may be observed in a downstroke phase (direction of arrow B), wherein the traveling valve 16 is open and, consequently, there is no pressure differential between the fluid flowing into the hollow piston 14 and the fluid above the fixed valve 18, that would promote the ingress of the abrasive solids a into the annulus 22 between the hollow piston 14 and the sleeve 12.
(17) FIG. 4 illustrates the pump 10 in an upstroke phase (depicted by arrow A). In this embodiment, the sleeve 12 has a lower portion 24 having the same outer diameter but a larger inside diameter having passages 28 therethrough, permitting communication of the gases present in the fluid with the annulus 24, thereby avoiding gas locks that can cause the traveling valve 16 and/or the fixed valve 18 to not operate as desired.
(18) FIG. 5A illustrates the detail Z1 of FIG. 4, while FIG. 5B illustrates the detail Z2 of FIG. 5A.
(19) FIG. 6 shows that the sleeve includes an outer wall 12b and an inner wall 12c, the inner wall have sections 12d, each section increases in width in an ascending direction with regard to an adjacent section forming a step 12a, thus an annular space 13 between the piston and the sleeve is reduced as the width of each section increases.
METHOD OF OPERATION
(20) In use, the pump 10 is inserted into a well casing or tubing 1. In the embodiment where the sleeve 12 is a unitary structure with the well casing or tubing 1 (as shown in FIGS. 2A and 2B), the pump is lowered until the piston 14 is slidably received into the sleeve 12. In the embodiment where the sleeve 12 is not a unitary structure with the well casing or tubing 1 (as shown in FIGS. 3, 4, 5A and 5B), sleeve 12 is lowered with the piston 14 and latched or sealed to the well casing or tubing 1, with an attachment liner or collet (not shown). The fixed valve 18 is seated in the well casing or tubing 1 in a manner known to those skilled in the art. In the operation of the pump 10 of the present invention, a conventional pumping apparatus (not shown) at the wellhead generates a pull that is transmitted to the pumping rod 26 (as shown in FIG. 4) and, from the pumping rod 26, to the hollow piston 14 that slides within the sleeve 14, which may be of a unitary structure with the well casing or tubing 1 (as shown in FIGS. 2A and 2B) or a separate component that is sealed or attached to well casing or tubing 1. When the hollow piston 14 is pulled upwardly in the upstroke phase, the traveling valve 16 closes to lift the fluid being extracted, as well as generating a vacuum to open fixed valve 18 to draw subsurface fluid into the well casing through the open fixed valve 18.
(21) In the downstroke phase of the pump 10, the hollow piston 14 is pushed downwardly by the pumping rod 26 (as shown in FIG. 3), causing the fixed valve 18 to close and the traveling valve 16 to open, pushing the fluid being extracted through the traveling valve 16 into the hollow piston 14.
(22) Any gases present in the fluid being extracted can escape into the well casing or tubing 1, so gas locks can be avoided and the hollow piston 14 can generate a sufficient draw to open the fixed valve 18.
(23) Specific measurements, diameters and lengths of the components of the pump 10 of the present invention-will be determined by those skilled in art depending on the type of fluid being extracted, whether water, petroleum or any other fluid.
