Patent Description:
Without limiting the scope of the present invention, the background will be described in relation to aging hydrocarbon producing wells where water encroachment may occur. In a healthy, optimally producing well, high pressure hydrocarbon or oil flow has the ability to lift this liquid to the surface. Over time, however, as the pressures in the formation decline and water production increases, the flow conditions change. The reservoir pressure may no longer be sufficient to unload the well such that water accumulates in the lower section of the well forming a column which further retards hydrocarbon production. Several pump-based solutions have been suggested to overcome the fluid accumulation problem and restore the flow rate of hydrocarbon producing wells. Plunger-type pump assemblies are limited by travel speed and typically operate in low pressure, lower production hydrocarbon producing wells in an advanced well life. Centrifugal-type pump assemblies are able to handle high production requests, but typically have a higher operational cost than plunger-type pump assemblies.

Further, as mentioned, over time, as the pressures in the formation decline and water production increases, the flow conditions and pressure conditions change. In existing pump assemblies, a rotational speed of a drive unit may be adjusted to compensate for the change in pressure conditions at a cost to the pump assemblies efficiency. Accordingly, there is a need for improved submersible pump assemblies and method for use of the same that efficiently operate across different hydrocarbon producing wells over the life of the hydrocarbon producing well.

<CIT> describes a wellbore pumping system submerged into a wellbore for unloading liquid from a wellbore comprising well fluid, such as gas, having a wellbore pressure, comprising a pump having an inlet and an outlet, a tubing fluidly connected with the outlet of the pump, and a driving unit connected with and powered by a cable, such as a wireline, and having a rotatable drive shaft for driving the pump, wherein the pump is a reciprocating pump comprising at least one pumping unit having a first moving member displaceable in a housing for sucking well fluid into and out of a first chamber.

<CIT> describes a submersible pumping system having an electric motor, a rotary hydraulic pump driven by the electric motor, and a linear hydraulic pump that is configured to move a production fluid.

<CIT> describes a hydraulic installation comprising a hydraulic motor for linearly or rotatively moving against a load, a first connection with a source of pressurized hydraulic fluid of mainly constant high pressure, a second connection with a source of pressurized hydraulic fluid of mainly constant low pressure, a hydraulic transformer for transforming a flow of hydraulic fluid of a first pressure into a flow of hydraulic fluid of a second pressure and connected to the first connection and the second connection and at least one connecting line connecting the hydraulic motor and the hydraulic transformer, the hydraulic transformer comprising a housing, a rotor freely rotatable in the housing, chambers in the rotor with means for changing the volume of the chambers between a minimum and a maximum value during a full rotation of the rotor and means for alternately connecting each chamber with the first connection, the second connection and the connecting line, and wherein the hydraulic motor and the hydraulic transformer are combined into a single unit connected to the first and the second connection.

It would be advantageous to achieve a submersible pump assembly and method for use of same that would improve upon existing limitations in functionality. It would also be desirable to enable a mechanical-based solution that would provide enhanced operational efficiently across different producing wells or other environments requiring the removal of fluid mediums with low viscosity, such as water or light crude oil. To better address one or more of these concerns, a submersible pump assembly and method for use of the same are disclosed. In one aspect, some embodiments include a cylinder block having cylinders and pistons. A drive shaft is rotatably supported in the cylinder block and coupled to a drive unit. An inclined leading plate is coupled to the pistons and the drive shaft such that pistons are configured to be axially driven in a reciprocating motion within the cylinders upon rotation of the inclined leading plate. A suction port and a pressure port are each located in fluid communication with the cylinders. In one operational mode, the fluid medium is transferred from the suction port to the pressure port during the reciprocating motion of the pistons, when the pistons are actively pumping. In another operational mode, the fluid medium is circulated through the suction chamber.

In another aspect, some embodiments include a submersible pump assembly for transference of a fluid medium with low viscosity is disclosed. In these embodiments, the submersible pump assembly includes multiple pump units co-axially aligned with a common drive shaft, a common suction chamber, and a common pressure chamber. Each of the pump units includes an active operational mode wherein the fluid medium is transferred from the common suction chamber to the common pressure chamber as well as an inactive operational mode wherein the fluid medium is circulated through the common suction chamber. Each of the pump units is individually actuatable.

In a still further aspect, some embodiments include multiple pump units co-axially aligned with a common drive shaft. Each of the multiple pump units is individually controllable such that the multiple pumps are serially positioned and controllable in parallel. Each of the multiple pump units include a drive shaft, which is rotatably supported in the cylinder block and coupled to a drive unit. An inclined leading plate is coupled to the pistons and the drive shaft such that pistons are configured to be axially driven in a reciprocating motion within the cylinders upon rotation of the inclined leading plate. A suction port and a pressure port are each located in fluid communication with the cylinders.

For a more complete understanding of the features and advantages of the present invention, reference is now made to the detailed description of the invention along with the accompanying figures in which corresponding numerals in the different figures refer to corresponding parts and in which:.

While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts, which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the present invention.

Referring initially to <FIG>, therein is depicted one embodiment of a submersible pump assembly <NUM> being employed in an onshore hydrocarbon production operation <NUM>, which may be producing oil, gas, or a combination thereof, for example. A wellhead <NUM> is positioned over a subterranean hydrocarbon formation <NUM>, which is located below a surface <NUM>. A wellbore <NUM> extends through the various earth strata including the subterranean hydrocarbon formation <NUM>. A casing string <NUM> lines the wellbore <NUM> and the casing string <NUM> is cemented into place with cement <NUM>. Perforations <NUM> provide fluid communication from the subterranean hydrocarbon formation <NUM> to the interior of the wellbore <NUM>. A packer <NUM> provides a fluid seal between a production tubing <NUM> and the casing string <NUM>. Composite coiled tubing <NUM>, which is a type of production tubing <NUM>, runs from the surface <NUM>, wherein various surface equipment <NUM> is located, to a fluid accumulation zone <NUM> containing a fluid medium F having a low viscosity, such as hydrocarbons like oil or gas, fracture fluids, water, or a combination thereof. As shown, the submersible pump assembly <NUM> is coupled to a lower end <NUM> of the production tubing <NUM>.

Referring now to figure <NUM> and figure <NUM>, as shown, the submersible pump assembly <NUM> is positioned in the fluid accumulation zone <NUM> defined by the casing string <NUM> cemented by the cement <NUM> within the wellbore <NUM>. The submersible pump assembly <NUM> is incorporated into a downhole tool <NUM> connected to the lower end <NUM> of the production tubing <NUM> and, more particularly, the submersible pump assembly <NUM> includes a housing <NUM> having a drive unit <NUM> coupled by a coupling unit <NUM> to serially positioned pump units <NUM>, <NUM>, <NUM>, which are, in turn, coupled to an intervention unit <NUM> and a connector <NUM>. The pump unit <NUM> may include ports <NUM>, <NUM>. Similarly, the pump unit <NUM> may include ports <NUM>, <NUM> and the pump unit <NUM> may include ports <NUM>, <NUM>. The various ports <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> may be assigned various inlet or outlet functions or be sealed shut. It should be appreciated that a variety of pump unit-configurations may be employed and number of pump units, as well as ports, may vary depending on the particular application that the submersible pump assembly <NUM> is assigned. By way of example, in one implementation, the pump units <NUM>, <NUM>, <NUM> may share a common inlet port.

In operation, to begin the processes of transferring the fluid medium F, the submersible pump assembly <NUM> is positioned in the fluid accumulation zone <NUM>. Initially, as shown best in figure <NUM>, the submersible pump assembly <NUM> is completely submerged in the fluid medium F, which, as mentioned, may include hydrocarbons such as oil and/or gas, fracture fluid, water, or combinations thereof. The submersible pump assembly <NUM> is actuated and selective operation of one or more of the pump units <NUM>, <NUM>, <NUM> begins. As time progresses, as shown best in figure <NUM>, the submersible pump assembly <NUM> pumps the fluid medium F, which may be a production fluid or a production inhibiting fluid, for example, to the surface <NUM>. The process of pumping the fluid medium F continues until the submersible pump assembly <NUM> is stopped.

In some embodiments, the submersible pump assembly <NUM> includes modularity to provide multiple pump units in a serial arrangement in a single volume represented by the housing <NUM>. The serial arrangement of the multiple pump units, however, provides for parallel operation with concurrent use of the pump units <NUM>, <NUM>, <NUM> to ensure redundancy. In particular, selective operation of the pump units <NUM>, <NUM>, <NUM> achieve total available low rate as well as a variable flow rate through the selective application of ON/OFF states to each of the pump units <NUM>, <NUM>, <NUM>.

Referring now to <FIG>, the submersible pump assembly <NUM> for transference of the fluid medium F with low viscosity is depicted in additional detail. As previously discussed, the housing <NUM> includes a drive unit <NUM> coupled by a coupling unit <NUM> to serially positioned pump units <NUM>, <NUM>, <NUM>, which are, in turn, coupled to an intervention unit <NUM> and a connector <NUM>, which, as shown, connects the submersible pump assembly <NUM> to the production tubing <NUM>. The intervention unit <NUM> may be co-axially aligned with the pump units <NUM>, <NUM>, <NUM> and permit the fluid medium F to bypass the pump units <NUM>, <NUM>, <NUM> as shown by arrow C. The housing <NUM> may include housing members for each of the drive unit <NUM> and pump units <NUM>, <NUM>, <NUM>. The pump units <NUM>, <NUM>, <NUM> are co-axially aligned with a common drive shaft <NUM>. The common drive shaft <NUM> may permit each of the pump units <NUM>, <NUM>, <NUM> to have its own drive shaft section with drive shaft sections united by special shape joint couplings and driven in a serial arrangement by the drive unit <NUM>. The common drive shaft <NUM> provides non-interfered power transmission to each of the pump units <NUM>, <NUM>, <NUM> via the central shaft hole for the common drive shaft <NUM>. Each of the pump units <NUM>, <NUM>, <NUM> may be the same with respect to structure and function.

A suction chamber <NUM> and a pressure chamber <NUM> are each located in fluid communication with the pump units <NUM>, <NUM>, <NUM>. The suction chamber <NUM> may include peripheral positioning and service each of the pump units <NUM>, <NUM>, <NUM> and provide a common suction chamber, which allows concurrent or parallel access by all of the pump units to a low pressure side of the fluid medium F being pumped. The suction chamber <NUM> includes an inlet port <NUM> with respective connection ports <NUM>, <NUM>, <NUM> to each of the pump units <NUM>, <NUM>, <NUM>. The inlet port <NUM> may be positioned in fluid communication with port <NUM>, for example. Each of the pump units <NUM>, <NUM>, <NUM> include respective connection ports <NUM>, <NUM>, <NUM> to the suction chamber <NUM>. The pressure chamber <NUM> may also include peripheral positioning and service each of the pump units <NUM>, <NUM>, <NUM> and provide a common pressure chamber, which allows concurrent or parallel access by all of the pump units <NUM>, <NUM>, <NUM> to a high pressure side of the fluid medium F being pumped. The pressure chamber <NUM> includes an outlet port <NUM> with respective connection ports <NUM>, <NUM>, <NUM> establishing fluid communication from the pump units <NUM>, <NUM>, <NUM> to the production tubing <NUM> at the connector <NUM>. The suction chamber <NUM> and the pressure chamber <NUM> provide each of the pump units <NUM>, <NUM>, <NUM> access to the fluid medium F. As all of the pump units <NUM>, <NUM>, <NUM> share the common suction chamber <NUM> and the common pressure chamber <NUM>, the number of pump units <NUM>, <NUM>, <NUM> may be modified as required. That is, any number of pump units <NUM>, <NUM>, <NUM> may be employed and the number of pump units <NUM>, <NUM>, <NUM> employed will depend on the application. In one implementation, a pump unit <NUM>, <NUM>, <NUM> may be designed with respect to available fluid medium F capacity, i.e., flow that can be attained in combination with the drive unit rotational speed and the selected suction chamber cross-section. The common suction chamber <NUM> and the common pressure chamber <NUM> are peripherally positioned and the size of the common suction chamber <NUM> and the common pressure chamber <NUM> defines the maximum possible pump unit flow rate of the fluid medium F.

By way of example and not by way of limitation, with respect to the pump unit <NUM>, a cylinder block <NUM> has multiple cylinders, including, for example, cylinders <NUM>, <NUM>, formed therein. The connection port <NUM> is connected to the suction chamber <NUM> to provide fluid communication to the cylinders <NUM>, <NUM>. The connection port <NUM> is also located in fluid communication with the cylinders <NUM>, <NUM>. The connection port <NUM> is located in fluid communication with the cylinders <NUM>, <NUM> as well. A respective number of pistons <NUM>, <NUM> are slidably received in each of the cylinders <NUM>, <NUM> and appropriately sealed thereat. The common drive shaft <NUM> is rotatably supported in the cylinder block <NUM> and the common drive shaft <NUM> is coupled to, and under the power of, the drive unit <NUM>. The cylinder block <NUM> is utilized to guide and support the pistons <NUM>, <NUM>. The cylinder block <NUM> may have equidistantly spaced bores serving as the cylinders <NUM>, <NUM> to accept the matching pistons <NUM>, <NUM>. The cylinder block <NUM> may include low friction sliding bushings that connect the cylinder block <NUM> and the pistons <NUM>, <NUM>. Sets of seals may be appropriately positioned within the cylinder block <NUM>. The pistons <NUM>, <NUM> push the fluid medium towards the pressure chamber <NUM>. In one implementation, each of the pistons <NUM>, <NUM> have circumferentially drilled holes that supply the fluid medium to the pistons <NUM>, <NUM> from the suction chamber <NUM>.

In one implementation, an inclined leading plate <NUM> is coupled to the pistons <NUM>, <NUM> and the common drive shaft <NUM>. The inclined leading plate <NUM> includes a tilt angle alpha that is selectively adjustable. Further, the inclined leading plate <NUM> is coupled to the pistons <NUM>, <NUM> such that the pistons <NUM>, <NUM> are configured to be axially driven in a reciprocating motion within the cylinders <NUM>, <NUM> upon rotation of the inclined leading plate <NUM>. A respective number of two-ball links <NUM>, <NUM> connect the inclined leading plate <NUM> to the pistons <NUM>, <NUM>. The inclined leading plate <NUM> is secured in place by sealing member <NUM> and bearing members <NUM> proximate an interface with the coupling unit <NUM>. A retainer plate <NUM> is secured to the inclined leading plate <NUM> with a bearing member <NUM>. The two-ball links <NUM>, <NUM>, in turn, are secured to the inclined leading plate <NUM> at the retainer plate <NUM>. The two-ball links <NUM>, <NUM> are designed to transfer linear, reciprocating motion from the retainer plate <NUM> to the pistons <NUM>, <NUM>. The form of the two-ball links <NUM>, <NUM> may be conditioned by the kinematic motion of the retainer plate <NUM> and the pistons <NUM>, <NUM>. As shown, a lubrication subsystem <NUM> may be co-located with the two-ball links <NUM>, <NUM>. In one embodiment, the lubrication subsystem reduces the friction between the pistons <NUM>, <NUM>, the two-ball links <NUM>, <NUM>, and the inclined leading plate <NUM> at the retainer plate <NUM>.

In one embodiment, the kinematic motion of the pistons <NUM>, <NUM> is achieved via a properly selected geometry of the inclined leading plate <NUM>. The angle of a contact surface with respect to the common drive shaft <NUM> connects the inclined leading plate <NUM> to the retainer plate <NUM> and the pistons <NUM>, <NUM>. Total inclination of the inclined leading plate <NUM> is limited by an inner diameter of the housing <NUM>. The retainer plate <NUM> may be designed to hold and guide the two-ball links <NUM>, <NUM> such that each of the two-ball links <NUM>, <NUM> may freely rotate but still transmit axial force to the appropriate piston <NUM>, <NUM>. The sealing member <NUM> may be designed to hold wear-resistant components and sealing components that prevent the fluid medium from contacting the inclined leading plate <NUM>. In this manner, the inclined leading plate <NUM> is lubricated by the lubrication subsystem <NUM>. Many low viscosity fluids do not have sufficient lubricating properties for high-load conditions, like the conditions that may be found proximate the two-ball links <NUM>, <NUM>. Therefore, the sealing and lubrication components at the two-ball links <NUM>, <NUM> ensure sufficient lubrication when the pump unit <NUM> is being utilized with low viscosity fluid mediums.

Check valves <NUM>, <NUM> are serially positioned within the cylinder block <NUM> at the cylinder <NUM> to service the piston <NUM>. Similarly, check valves <NUM>, <NUM> are serially positioned within the cylinder block <NUM> at the cylinder <NUM> to service the piston <NUM>. The check valves <NUM>, <NUM> cooperate to prevent backpressure by opening during an intake stroke and closing during an exhaust stroke. A valve plate connection <NUM> is positioned at the cylinder block <NUM> and secured to a valve plate <NUM> actuatable by a drive member <NUM>. The valve plate <NUM> may be utilized to control the flow of the fluid medium F, on a pump unit-by-pump unit basis, by rotating the valve plate <NUM> by a predetermined angle via the driver member <NUM>. For example, in one embodiment, the valve plate <NUM> may be set to an arrangement whereby the fluid medium F is permitted to flow into the pressure chamber <NUM> during active pumping. Alternatively, the valve plate <NUM> may be set to an arrangement whereby the fluid medium F returns to the suction chamber <NUM>, via the connection port <NUM>, for example, with respect to the pump unit <NUM>. It should be appreciated that the valve plate <NUM> includes proper sealing components to prevent any connection between the suction chamber <NUM> and the pressure chamber <NUM>. By way of example, a sealing member <NUM> positioned at the junction between the pump unit <NUM> and the pump unit <NUM> prevents any leaking at the connection between the suction chamber <NUM> and the pressure chamber <NUM>. Similarly, a sealing member <NUM> positioned at the junction between the pump unit <NUM> and the pump unit <NUM> also prevents any leaking at the connection between the suction chamber <NUM> and the pressure chamber <NUM>. A connection assembly <NUM> represents the flanges, gaskets, seals, and other physical components that connect the pump unit <NUM> to the coupling unit <NUM>. Similarly, a connection assembly <NUM> is positioned between the pump unit <NUM> and the pump unit <NUM>; a connection assembly <NUM> is positioned between the pump unit <NUM> and the pump unit <NUM>; and a connection assembly <NUM> is positioned between the pump unit <NUM> and the intervention unit <NUM>. The housing <NUM> of the submersible pump assembly <NUM> also provides the space for communication lines, control and service lines, acquisition and data lines, and power lines. The size and positioning of these additional utilities does not diminish the strength of operation of the submersible pump assembly <NUM>.

In an active pumping or active operational mode when the pistons <NUM>, <NUM> are active, the fluid medium F is transferred from the connection port <NUM> at the suction chamber <NUM> to the connection port <NUM> at the pressure chamber <NUM> during the reciprocating motion of the pistons <NUM>, <NUM>. That is, the fluid medium F flows as shown by arrows A and arrows B. On the other hand, in an inactive pumping or inactive operational mode when the pistons <NUM>, <NUM> are circulating the fluid medium F, the fluid medium F is transferred from the connection port <NUM> at the suction chamber <NUM> through the cylinder block <NUM> and out of the connection port <NUM> to the suction chamber <NUM>, as shown by arrows A and arrows B'. During active pumping, the submersible pump assembly <NUM> generates flow of fluid medium F by creating a positive pressure difference between the suction side at the suction chamber <NUM> and the pressure side at the pressure chamber <NUM>. The pressure difference is achieved by the radial positioning of the moving pistons <NUM>, <NUM> with an accompanying number of the check valve pairs, such as check valves <NUM>, <NUM>, <NUM>, <NUM>, that open and close in an alternating manner to prevent the pressurized fluid medium F from running back. That is, each of the check valves <NUM>, <NUM>, <NUM>, <NUM> prevents backpressure by, with respect to the pistons <NUM>, <NUM>, opening during an intake stroke and closing during an exhaust stroke. The design of the submersible pump assembly <NUM> allows each pump unit <NUM>, <NUM>, <NUM> to selectively pump fluid medium F into the pressure sided at the pressure chamber <NUM> in an active operational mode or circulate the fluid medium F through the suction chamber <NUM> during an inactive operational mode when the pump units <NUM>, <NUM>, <NUM> are pumping to circulate the fluid medium F. During the inactive pumping mode, an individual pump unit <NUM>, <NUM>, <NUM> does not add anything to the total pumping flow rate since the fluid medium F is circulating to and from the suction chamber <NUM>. In this inactive operational mode, a pump unit is not loaded and may be idle or redundant and continue in this mode of operation indefinitely.

The submersible pump assembly <NUM> presented herein functions to remove fluid mediums with low viscosity, such as water or light crude oil, for example. As discussed, the submersible pump assembly <NUM> provides for installation in confined spaces such as pipes, below or above the ground level, near or at a remote location. Optionally, the submersible pump assembly <NUM> may be utilized with other downhole tools, such as hydrocarbon and solid particle separators, sensors, and measuring devices, for example. Further, as discussed, any number of pump units <NUM>, <NUM>, <NUM> may be utilized in the submersible pump assembly <NUM> to provide redundancy as well as, through selectively actuation, calibration of the fluid medium transference required. Further, in instances of multiple pump units, like pump units <NUM>, <NUM>, <NUM>, each of the pump units <NUM>, <NUM>, <NUM>, may individually and selectively actuated to pump the fluid medium F from the suction chamber <NUM> to the pressure chamber <NUM> or circulate the fluid medium F through the suction chamber <NUM>.

Claim 1:
A submersible pump assembly (<NUM>) for transference of a fluid medium with low viscosity, the submersible pump assembly (<NUM>) comprising:
a cylinder block (<NUM>) having a plurality of cylinders (<NUM>, <NUM>) formed therein;
a first port (<NUM>) located in fluid communication with the plurality of cylinders (<NUM>, <NUM>) and a suction chamber (<NUM>);
a second port (<NUM>) located in fluid communication with the plurality of cylinders (<NUM>, <NUM>) and a pressure chamber (<NUM>);
a third port (<NUM>) located in fluid communication with the plurality of cylinders (<NUM>, <NUM>) and the suction chamber (<NUM>);
a respective plurality of pistons (<NUM>, <NUM>) slidably received in each of the plurality of cylinders (<NUM>, <NUM>);
a drive shaft (<NUM>) rotatably supported in the cylinder block (<NUM>), the drive shaft (<NUM>) being coupled to a drive unit (<NUM>);
an inclined leading plate (<NUM>) coupled to the plurality of pistons (<NUM>, <NUM>) and the drive shaft (<NUM>), the inclined leading plate (<NUM>) coupled to the plurality of pistons (<NUM>, <NUM>) such that the plurality of pistons (<NUM>, <NUM>) are configured to be axially driven in a reciprocating motion within the plurality of cylinders (<NUM>, <NUM>) upon rotation of the inclined leading plate (<NUM>);
a first operational mode wherein the fluid medium is transferred from the first port (<NUM>) to the second port (<NUM>) during the reciprocating motion of the plurality of pistons (<NUM>, <NUM>);
a second operational mode wherein the fluid medium is transferred from the first port (<NUM>) to the third port (<NUM>); and
a valve plate (<NUM>) having a first position and a second position, the valve plate (<NUM>) selectively actuatable under control of a drive member (<NUM>) between the first position and the second position, the first position corresponding to the first operational mode, the second position corresponding to the second operational mode.