PUMPDOWN ASSIST TOOL FOR WIRELINE OPERATIONS

Abstract

A pumpdown assist device has an outer housing comprising a top connection, a spring housing, a piston housing and a bottom connection, all defining a central bore; a mandrel disposed and slidably moveable within the central bore between a run-in-hole (RIH) position and a pull-out-of-hole (POOH) position, the mandrel comprising a head portion, a central portion and a bottom stem, all defining a central passage, wherein the head portion comprises a flow restriction from the top connection central bore; a piston connected to the mandrel and having a sloped ramp surface; a plurality of pads slidably disposed on the piston ramp surface and which are transversely moveable through pad cutouts defined by the piston housing; and biasing means disposed within the spring housing, for urging the mandrel in its POOH position. The device is installed into a bottom hole assembly (BHA) and is urged into a wellbore by pumping down fluid. When fluid pressure within the device top connection exceeds the biasing means force, the mandrel is shifted to the RIH position and the pads are deployed outwards. Sufficient flow rate is then maintained to maintain deployment pressure in the device top connection until the BHA reaches a desired depth. The pads may then be retracted into a POOH position by reducing pumpdown flow rate.

Description

FIELD OF THE INVENTION

The present invention generally relates to a pumpdown tool for wireline operations in a wellbore.

BACKGROUND

Pumpdown perforating, known colloquially as “plug and perf” is a wireline-conveyed method of completing horizontal wells. Fluid pumped from surface is used to convey a plug and perforating guns to a desired depth, where the plug is set and the guns are fired, creating openings through the casing and cement and into the formation. The perforations provide reservoir access for subsequent fracturing operations.

Pumpdown perforating is generally performed in conjunction with fracturing services. After each fracturing operation, a frac plug and perforating guns are lowered into the well and pumped down to isolate the completed stage and prepare the next stage for fracturing. This process is repeated until all stages in the well have been completed according to the well design.

Typically, a composite frac plug is made up to a wireline bottom hole assembly (BHA) that includes a plug, setting tool, and perforating guns. This BHA is dropped down to the kickoff point in a horizontal well and then pumps are used to deploy it to its intended location. After setting, the wireline BHA will be used to perforate the casing above the plug and then removed from the well. The surface frac equipment will then be rigged up. For a ball drop plug, a ball will be dropped from surface. Once reaching the horizontal part of the well it will be pumped down to land on the plug, isolating the well into two sections. Bridge plugs may be used, which do not allow flow until it is retrieved or milled out.

There remains a need in the art for efficient methods of plug and perf wireline operations.

SUMMARY OF THE INVENTION

The present disclosure relates to a pumpdown assist tool for wireline operations.

In one claim, described is a pumpdown assist device comprising:

• • (a) an outer housing comprising a top connection, a spring housing, a piston housing and a bottom connection, together defining a central bore;
  • (b) a mandrel disposed and slidably moveable within the central bore between a run-in-hole (RIH) position and a pull-out-of-hole (POOH) position, the mandrel comprising a head portion, a central portion and a bottom stem, together defining a central passage, wherein the head portion defines a flow restriction from the top connection central bore;
  • (c) a piston connected to the mandrel and having a sloped ramp surface;
  • (d) a plurality of pads slidably disposed on the piston ramp surface and which are transversely moveable through the piston housing;
  • (e) biasing means disposed within the spring housing, for urging the mandrel to its POOH position.

In another claim, described is a method of pumping down a wireline bottom hole assembly (BHA), comprising the steps of:

• • (a) assembling a BHA with a pumpdown assist device a pumpdown assist device comprising:
    • i. an outer housing comprising a top connection, a spring housing, a piston housing and a bottom connection, all defining a central bore;
    • ii. a mandrel disposed and slidably moveable within the central bore between a run-in-hole (RIH) position and a pull-out-of-hole (POOH) position, the mandrel comprising a head portion, a central portion and a bottom stem, all defining a central passage, wherein the head portion defines a flow restriction from the top connection central bore;
    • iii. a piston connected to the mandrel and having a sloped ramp surface;
    • iv. a plurality of pads slidably disposed on the piston ramp surface and which are transversely moveable through the piston housing;
    • V. biasing means disposed within the spring housing, for urging the mandrel in its POOH position;
    • (b) pumping down fluid to convey the BHA into the wellbore until the fluid pressure within the device top connection exceeds the biasing means force, thereby shifting the mandrel to the RIH position and deploying the pads outwards;
    • (c) maintaining sufficient fluid flow rate to maintain deployment pressure in the device top connection until the BHA reaches a desired depth;
    • (d) retracting the pads towards a POOH position by reducing pumpdown flow rate.

BRIEF DESCRIPTION OF THE FIGURES

The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate some, but not the only or exclusive, examples of embodiments and/or features.

FIG. 1 shows a longitudinal cross-sectional view of one embodiment of a pumpdown assist tool; in a “pull out of hole” or “POOH” configuration.

FIG. 2A shows a cross-sectional view of the embodiment of FIG. 1, in a “run-in hole” or “RIH” configuration.

FIG. 3 shows a central mandrel.

FIG. 4 shows a spring housing.

FIG. 5A shows a piston. FIG. 5B shows the piston in longitudinal cross-section. FIG. 5C shows a bottom plan view of the piston.

FIG. 6 shows a piston housing.

FIG. 7A shows a pad. FIG. 7B shows a side plan view of the pad.

FIG. 8 shows a transverse cross-section of the embodiment of FIG. 1, with the pads retracted in a POOH configuration.

FIG. 9 shows the cross-section of FIG. 8, with the pads extended in a RIH configuration.

FIG. 10 shows a schematic of a plug and perf bottom hole assembly (BHA) incorporating one embodiment of a pumpdown assist tool

DETAILED DESCRIPTION

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are exemplified. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout. It is to be understood that this invention is not limited to the particular methodology and protocols described, as such may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention.

Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which the invention pertains having the benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

In this description, the directional prepositions of up, upwardly, down, downwardly, front, back, top, upper, bottom, lower, left, right and other such terms refer to the device as it is oriented and appears in the drawings and are used for convenience only; they are not intended to be limiting or to imply that the device has to be used or positioned in any particular orientation. The term “longitudinal” means the direction aligned with the long axis of the tool, while the term “radial” or “transverse” means a direction or plane which is normal or perpendicular to the longitudinal direction. Conventional components of the invention are elements that are well-known in the prior art and will not be discussed in detail for this disclosure.

As exemplified in FIG. 1, a pumpdown assist tool 10 comprises a top connection 12, a spring housing 14, a piston housing 16, and a bottom connection 18, all defining a central longitudinal bore. Within the tool 10 is a central mandrel 20, and a piston 26, and radially extendible pads 28. The top connection 12 and the bottom connection 18 may be used to connect the tool into the BHA, using threaded connections, as is well known in the art. Generally, the tool is configured to use fluid pressure above the tool to move the piston 26 downward, thereby extending the pads 28 radially outward when it is desired to do so.

As may be seen in FIG. 1, the tool 10 is in a POOH configuration, with the pads 28 retracted. This is also the configuration of the tool when making up the BHA, and when descending into the wellbore with gravity alone.

The central mandrel 20 has a head portion 20a which slides within the spring housing 14 and is sealed within the spring housing with, for example, an O-ring seal. When in the POOH position, the head portion abuts against a lower end of the top connection 12. Below the head portion 20a, the central mandrel 20 comprises a central portion 20b and a lower stem 21. The central portion slides within a lower shoulder 25 of the spring housing, also sealed with an O-ring. The central portion 20b and the spring housing 14 form an annular space spring chamber within which a biasing means 24, such as a coil spring for example, is disposed which bears on the shoulder 25 and the head portion 20a of the mandrel 20, urging the mandrel upwards. Preferably, the spring housing 14 is perforated to ensure fluid circulation within the spring housing to keep debris clear of the spring 24 and to allow fluid ingress and egress as the spring chamber contracts and expands.

The mandrel 20 defines an inner bore 1 which defines a significantly reduced flow area as compared to the top connection bore 2. When pumpdown pumps are activated, increasing the flowrate of fluid through the mandrel 20, there is a resulting pressure build up which drives the mandrel 20 downwards, compressing the spring 24, as may be seen in FIG. 2. The strength of the spring can be selected to be overcome by the desired pumpdown flowrate, and also to return the tool to a POOH configuration (FIG. 1) when it is desired to do so.

Piston 26 is connected to the mandrel 20, around the lower stem 21 of the mandrel. The upper end of the piston 26 contacts a shoulder 27 formed by the transition of the central portion 20b to the lower stem 21. The piston 26 has an inverted conical or pyramidal shape as a result of a transverse cross-sectional area which gradually gets smaller from top to bottom, thus defines a ramp surface 26a. In preferred embodiments, the piston has a quadrilateral cross-sectional shape with rounded corners, as shown in FIG. 5C, and thus comprises four piston ramp surfaces. In other embodiments, the piston may have a circular shape or other suitable geometry. The shape may define the number of ramp surfaces available. In preferred embodiments, each ramp surface define a longitudinal T-track 26b which retains and guides a pad rail 28b. The ramp surfaces 26a may define a plurality of openings 26c which allow for fluid circulation to flush debris from the T-tracks 26b.

One embodiment of a pad 28 is shown in FIGS. 7A and 7B. The pad has a curved outer surface 28a, to provide a substantially flush surface with the cylindrical piston housing 16 when retracted in a POOH position, as shown in FIG. 8. The inner surface of pad has a slope matching the slope of the piston ramp surface 16a, and a T-rail 28b which mates with and slides within the T-track 26b of the piston. The pad 28 is retained in the pad cutout 16a of the piston housing 16. The pads can comprise a shape which matches a cutout shape through the piston housing, which limits non-transverse movement of the pads. The shape preferably includes a tab 16b which corresponds with pad groove 28c, which assists in retaining the pad 28 within the pad cutout through its range of motion. The pad 28 thus rides on the piston 26 and is moved radially inward and outward through the pad cutout 16a, as the piston moves upwards and downwards longitudinally within the tool.

The number of pads, and the dimensions of the pads may be chosen to provide a designed reduction in the open flow area around the outside of the device 10 when deployed in the RIH position. Obviously, the greater the reduction, the more resistance the device will provide to flow of the pumpdown fluid around the device.

In an exemplary operation, the device 10 is assembled into a wireline BHA as is shown in FIG. 10 and inserted into a wellbore. The wireline (not shown) passes within the internal bore of the tool through to the cable head. A fishneck and weight bars can also be used as is well known. The lower end of the BHA is conventionally configured, and includes perforating guns, a setting sleeve and a frac plug.

Typically, the BHA can descend to the transition or horizontal section of the wellbore with gravity alone. Once the BHA reaches the transition or horizontal section of the wellbore, pumpdown pumping can begin. As the flowrate of pumpdown fluid increases, the fluid pressure above the mandrel 20 will increase as a result of the restricted fluid flow through the mandrel 20. As a result, when the fluid pressure compresses spring 24, the mandrel is pushed downwards within the tool 10, which causes the piston 26 to move downwards, thereby actuating the pads 28 radially outward. This significantly reduces the effective flow area around the outside of the tool, as may be seen in FIG. 9. As a result, the tension on the wireline will increase, and the operator may unspool the wireline faster, allowing for faster descent of the BHA into the wellbore.

Ports 12a in the top connection 12 and ports 18a in the bottom connection allow for pressure equalization in the annular space around the tool and can also prevent debris from accumulating in and around the device by permitting continuous fluid circulation through the ports 12a and 18a.

Once the BHA nears its desired position, the pump rate and fluid flow will slow, and the pressure within the device 10 above the mandrel 20 decreases until it no longer exceeds the force of the spring 24. Accordingly, the mandrel 20 will be pushed upwards by the spring, which pulls the piston 26 upwards, thereby retracting the pads. The BHA can then be retrieved by pulling out of hole, as the pads have fully retracted.

The actuation and retraction of the pads in this device is thus accomplished without any active components which require sensors and power actuators. Accordingly, no electric connections or lines are necessary. As may be appreciated by those skilled in the art, the activation pressure may be varied by varying the diameter of the central bore in the mandrel and the strength of the spring. Fluid pressure above the device 10 is affected by pump rate and speed of the BHA relative to fluid flowrate. A balance may be reached to ensure actuation and retraction of the pads when desired. When pulling out of hole, a significant pressure buildup may occur due to the rapid upward movement of the BHA against a static fluid column. Ports 12a allow fluid to escape, thereby reducing this pressure and prevent unwanted actuation of the pads.

The use of a pumpdown assist device 10 may promote healthy wireline cables by reducing the tension differential between RIH and POOH. This keeps the wireline cable normalized and prevents common cable failures such as torque knots, bird cages, & high strands. Faster RIH speeds may reduce frac standby and overall job time. The pumpdown assist device may achieve the same BHA pumpdown speed with a lower flow rate, which may allow for reduced water consumption and potentially significant cost savings and environmental impacts.

In one embodiment, the pumpdown assist device 10 may allow the BHA to be deployed without the use of a frac plug, to perform a hybrid completion safely and effectively while eliminating the costs associated with coil tubing milling following pad completion. By providing pumpdown assist with this device, the frac plug can be removed from the BHA and replaced with a ball drop and seat system to isolate the previous zone. This eliminates the need for coil tubing to mill out the frac plugs once the job is complete. This could result in significant cost savings and timeline improvements, as well as reducing servicing and failure points for the wireline crew by eliminating the setting tool and frac plug from the BHA.

Interpretation.

The forgoing description supplies specific details in order to provide a thorough understanding. Nevertheless, the skilled artisan would understand that the apparatuses, systems, and associated methods of using the apparatuses and systems can be implemented and used without employing these specific details. Indeed, the apparatuses, systems, and associated methods can be placed into practice by modifying the illustrated apparatus and associated methods and can be used in conjunction with any other apparatus and techniques conventionally used in the industry.

The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims appended to this specification are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed.

References in the specification to “one embodiment”, “an embodiment”, etc., indicate that the embodiment described may include a particular claim, feature, structure, or characteristic, but not every embodiment necessarily includes that claim, feature, structure, or characteristic. Moreover, such phrases may, but do not necessarily, refer to the same embodiment referred to in other portions of the specification. Further, when a particular claim, feature, structure, or characteristic is described in connection with an embodiment, it is within the knowledge of one skilled in the art to affect or connect such module, claim, feature, structure, or characteristic with other embodiments, whether or not explicitly described. In other words, any module, element or feature may be combined with any other element or feature in different embodiments, unless there is an obvious or inherent incompatibility, or it is specifically excluded.

It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for the use of exclusive terminology, such as “solely,” “only,” and the like, in connection with the recitation of claim elements or use of a “negative” limitation. The terms “preferably,” “preferred,” “prefer,” “optionally,” “may,” and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention.

The singular forms “a,” “an,” and “the” include the plural reference unless the context clearly dictates otherwise. The term “and/or” means any one of the items, any combination of the items, or all of the items with which this term is associated. The phrase “one or more” is readily understood by one of skill in the art, particularly when read in context of its usage.

As will also be understood by one skilled in the art, all language such as “up to”, “at least”, “greater than”, “less than”, “more than”, “or more”, and the like, include the number recited and such terms refer to ranges that can be subsequently broken down into sub-ranges as discussed above. In the same manner, all ratios recited herein also include all sub-ratios falling within the broader ratio.

Claims

1. A pumpdown assist device comprising: (a) an outer housing comprising a top connection, a spring housing, a piston housing and a bottom connection, all defining a central bore;(b) a mandrel disposed and slidably moveable within the central bore between a run-in-hole (RIH) position and a pull-out-of-hole (POOH) position, the mandrel comprising a head portion, a central portion and a bottom stem, all defining a central passage, wherein the head portion comprises a flow restriction from the top connection central bore;(c) a piston connected to the mandrel and having a sloped ramp surface;(d) a plurality of pads slidably disposed on the piston ramp surface and which are transversely moveable through the piston housing;(e) biasing means disposed within the spring housing, for urging the mandrel in its POOH position.

2. The device of claim 1, wherein the pads comprise a rail which mates with a channel formed on the piston, to guide the pads as they slide along the piston ramp surface.

3. The device of claim 1 wherein the pads comprise a shape which matches a cutout shape through the piston housing, which limits non-transverse movement of the pads.

4. The device of claim 1, wherein the biasing means comprises a coil spring.

5. The device of claim 1, wherein the spring housing and/or piston housing defines a plurality of openings for fluid circulation.

6. The device of claim 1, wherein the piston has a quadrilateral cross-sectional shape, with four sloped ramp surfaces.

7. A method of pumping down a wireline bottom hole assembly (BHA), comprising the steps of: (a) assembling a BHA with a device, wherein the device is responsive to fluid pressure to outwardly deploy one or more pads to reduce flow area around the BHA;(b) pumping down fluid to urge the BHA into the wellbore and deploy the pads outwards;(c) maintaining sufficient flow rate to maintain deployment pressure until the BHA reaches a desired depth; and(d) retracting the pads inwardly by reducing pumpdown flow rate.

8. The method of claim 7, wherein the device comprises a device of claim 1.

9. A bottom hole assembly for wireline plug and perf, comprising a device which is responsive to fluid pressure to outwardly deploy one or more pads to reduce flow area around the BHA.

10. The bottom hole assembly of claim 9 wherein the device comprises a device of claim 1.