PRESSURE DIFFERENTIAL PLUG AND METHOD

Abstract

A pressure differential plug including a mandrel, a baffle within the mandrel, and one or more passageways in the baffle, the passageways configured and dimensioned to restrict flow therethrough due to a valve coefficient thereof to both allow fluid flow therethrough and simultaneously allow the building of actuation pressure against the baffle without landing a member on the baffle. A borehole system including a borehole, a string in the borehole, the string including a plug as as in any prior embodiment. A method for causing an actuation via pressure including flowing fluid through a baffle of a plug as in any prior embodiment, increasing a flow rate through the baffle to raise pressure upstream of the baffle to an actuation level without seating a member on the baffle.

Description

BACKGROUND

In the drilling and completion industry, there is often a need to run and set plugs in an open hole or a cased hole or even in a tubing string for the purpose of allowing an operator to apply pressure from surface. That pressure may be used for things such as setting other tools or treating the formation including fracturing the formation. Using such configurations is a two-step process. The plug (aka seat) is set in the downhole environment and later a ball or similar is dropped to land on the plug or seat thereby presenting a restriction to fluid flow such that pressure may be built against this combination of components. This type of configuration has worked extremely well in the industry for an extended period of time. The industry is however always open to improvements in configurations and methods that enhance efficiency or reduce components and therefore cost.

SUMMARY

A pressure differential plug including a mandrel, a baffle within the mandrel, and one or more passageways in the baffle, the passageways configured and dimensioned to restrict flow therethrough due to a valve coefficient thereof to both allow fluid flow therethrough and simultaneously allow the building of actuation pressure against the baffle without landing a member on the baffle.

A borehole system including a borehole, a string in the borehole, the string including a plug as as in any prior embodiment.

A method for causing an actuation via pressure including flowing fluid through a baffle of a plug as in any prior embodiment, increasing a flow rate through the baffle to raise pressure upstream of the baffle to an actuation level without seating a member on the baffle.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:

FIG. 1 is a longitudinal cross sectional view of a Pressure Differential Plug as described herein;

FIG. 2 is a side view of FIG. 1 in the direction of arrows 1-1 in FIG. 1;

FIG. 3 is a transparent view of an alternate baffle having tortuous passageways;

FIG. 4 is another view of a baffle plate with more passageways than that shown in FIG. 2; and

FIG. 5 is an enlarged view of a portion of the baffle of FIG. 4 illustrating sand particles bridging over the passageways.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.

Referring to FIGS. 1 and 2 simultaneously, a Pressure Differential Plug 10 is disclosed that allows for a pressure differential to be created sufficient to take desired borehole actions based upon pressure without the loss of the ability to flow fluid through the plug. The plug 10 is illustrated with a packer 12 but it is to be understood that the disclosure hereof is directed to the inner portions of the tool such that providing tubing pressure cannot otherwise escape to an annulus 14, a packer would not be needed. In one embodiment, and as illustrated, the action being taken by application of pressure to the tubing is to treat the formation. In that case, the fluid inside the tubing will necessarily be open to the annulus 14 and hence the packer would be needed. The plug 10 includes a tubular mandrel 16 within which a baffle 18 is disposed. The baffle may be secured in the mandrel 16 with threads 17, screws, welding, adhesives, or be formed therein. The baffle 18 may also be a part of the mandrel 16 as in having been formed as a part of the mandrel 16. For example, the baffle 18 may be either subtractively machined or additively manufactured as a part of the mandrel 16.

The baffle 18, most easily identified in FIG. 2, includes a number of passageways 20 therein that range from 1 to any number of passageways that are practically positionable in the area provided by the particular baffle 16. For example, as illustrated there are 12 passageways 20. It is to be appreciated that a larger number of passageways may be achieved by using smaller diameters of the passageways. While “diameter” is used for discussion purposes, there is no reason the passageways must necessarily be cylindrical but rather any tubular form may be employed as desired.

Important to the teaching herein is that in all embodiments hereof regardless of the number of passageways, size of passageways or shape of passageways, the passageways 20 collectively must restrict flow therethrough due to a valve coefficient thereof to both allow fluid flow therethrough and simultaneously allow the building of actuation pressure against the baffle without landing a member on the baffle. In an embodiment the actuation pressure is a formation fracture pressure and in another embodiment the actuation pressure is that pressure associated with the actuation of a downhole tool. In embodiments the passageways collectively must have a valve coefficient of less than 4.47. This can be determined for a particular embodiment by using the equations:

Q_gpm=C_v*(ρ_water*ΔP/ρ)̂0.5 or rewritten as Q_gpm=C_v*(ΔP/SG)̂0.5 or rewritten as C_v=Q_gpm/(ρ_water*ΔP/ρ)̂0.5 or rewritten as C_v=Q_gpm/(ΔP/SG)̂0.5

Q_gpm=Flow Rate (gpm)

C_v=Valve Coefficient

ρ=Density (lb/ft³)

ρ_water=Water Density (lb/ft³)=62.4 lb/ft³

ΔP=Pressure Drop (psi)

SG=Specific gravity of the fluid

Maintaining configurations with a valve coefficient of less than 4.47 provides for a condition where applied flow rate and pressure from the surface will reach high enough levels in a target region to achieve the operation desired, for example a fracturing job, all while maintaining a flowing fluid dynamic at the plug site (i.e. no member is seated on the baffle). This allows for tools to be pumped to depth even with the plug 10 in place, if desired. This avoids the difficulties of very early plugs that prevent all fluid flow once set and the difficulties of those traditional plugs that utilize a seat to preserve fluid flow when set but require a ball drop (or similar member) to land on the seat to enable pressure up. And it will be appreciated by those of skill in the art that once the ball is seated, flow through is prevented and hence pumping other or additional tools to the site is not possible without removing the ball.

As illustrated, plug 10 also includes standard anchoring equipment 22 such as one or more slips 22 or other similar equipment.

In use, the plug 10 is installed in a tubular form which may be an open hole, a casing, a tubing, etc. and anchored there. A flow rate for flowing through the plug 10 may initially be established and then increased to a level where pressure is built against the baffle 18 and fracturing may occur. It will be understood that after setting of the plug 10, an operator may elect to run a set of guns to open the casing of tubing for access to the formation for a fracturing operation.

Further disclosed herein is a borehole system that includes a borehole 24 within which a string 26 (casing, tubing, etc.) is positioned and the string including a plug 10 as described above.

In an alternate embodiment, referring to FIG. 3, baffle 118 includes passageways 120 that are tortuous over their lengths. Tortuosity may be employed to alter the valve coefficient of a baffle 118. While the tortuous path illustrated is a squared off path, it is to be understood that any tortuous path is acceptable such as a curved path, helical path, etc. as is desired to create the valve coefficient needed while avoiding some other parameters that might otherwise be employed to secure the desired valve coefficient.

In yet another embodiment, referring to FIGS. 4 and 5, a baffle 218 is illustrated with many passageways 220. In combination with the valve coefficient as described above, it is also contemplated for this embodiment that particles 240 such as sand or similar may be used to bridge over the individual passageways 220 further inhibiting fluid flow therethrough.

Providing the velocity of fluid flow is sufficient to carry sand particles, which is dictated by Stokes law, to wit:

w=2*(ρ_p'1ρ_f)*g*r²/(9*μ)

• w=Particle settling velocity

ρ=fluid density (subscripts p and f indicate particle and fluid respectively)

g=the acceleration due to gravity

r=the radius of the particle and

μ=the dynamic viscosity of the fluid,

then the particles 240 will be carried along in the fluid flow to the baffle 218 and will bridge across the passageways 220 as seen in FIG. 5.

Set forth below are some embodiments of the foregoing disclosure:

Embodiment 1: A pressure differential plug including a mandrel, a baffle within the mandrel, and one or more passageways in the baffle, the passageways configured and dimensioned to restrict flow therethrough due to a valve coefficient thereof to both allow fluid flow therethrough and simultaneously allow the building of actuation pressure against the baffle without landing a member on the baffle.

Embodiment 2: The plug as in any prior embodiment wherein the one or more passageways collectively present a valve coefficient of less than 4.47.

Embodiment 3: The plug as in any prior embodiment wherein the plug further includes a packer and anchoring equipment.

Embodiment 4: The plug as in any prior embodiment wherein the baffle is secured in the mandrel with threads.

Embodiment 5: The plug as in any prior embodiment wherein the baffle is formed as a part of the mandrel.

Embodiment 6: The plug as in any prior embodiment wherein the one or more passageways are cylindrical.

Embodiment 7: The plug as in any prior embodiment wherein the one or more passageways are tortuous.

Embodiment 8: A borehole system including a borehole, a string in the borehole, the string including a plug as as in any prior embodiment.

Embodiment 9: A method for causing an actuation via pressure including flowing fluid through a baffle of a plug as in any prior embodiment, increasing a flow rate through the baffle to raise pressure upstream of the baffle to an actuation level without seating a member on the baffle.

Embodiment 10: The method as in any prior embodiment further including flowing particles to bridge over the one or more passageways in the baffle.

Embodiment 11: The method as in any prior embodiment wherein the actuation is fracturing.

Embodiment 12: The method as in any prior embodiment wherein the actuation is of another tool.

Embodiment 13: The method as in any prior embodiment further including returning fluid flow to a level below pressure increase and flowing fluid through the baffle.

Embodiment 14: A method for making a pressure differential plug as in any prior embodiment wherein the baffle is subtractively machined in the mandrel.

Embodiment 15: The method as in any prior embodiment wherein the baffle is additively manufactured with the mandrel.

The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Further, it should further be noted that the terms “first,” “second,” and the like herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The modifier “about” used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (e.g., it includes the degree of error associated with measurement of the particular quantity).

The teachings of the present disclosure may be used in a variety of well operations. These operations may involve using one or more treatment agents to treat a formation, the fluids resident in a formation, a wellbore, and/or equipment in the wellbore, such as production tubing. The treatment agents may be in the form of liquids, gases, solids, semi-solids, and mixtures thereof. Illustrative treatment agents include, but are not limited to, fracturing fluids, acids, steam, water, brine, anti-corrosion agents, cement, permeability modifiers, drilling muds, emulsifiers, demulsifiers, tracers, flow improvers etc. Illustrative well operations include, but are not limited to, hydraulic fracturing, stimulation, tracer injection, cleaning, acidizing, steam injection, water flooding, cementing, etc.

While the invention has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited.

Claims

1. A pressure differential plug comprising:

a mandrel;

a baffle within the mandrel; and

one or more passageways in the baffle, the passageways configured and dimensioned to restrict flow therethrough due to a valve coefficient thereof to both allow fluid flow therethrough and simultaneously allow the building of actuation pressure against the baffle without landing a member on the baffle.

2. The plug as claimed in claim 1 wherein the one or more passageways collectively present a valve coefficient of less than 4.47.

3. The plug as claimed in claim 1 wherein the plug further includes a packer and anchoring equipment.

4. The plug as claimed in claim 1 wherein the baffle is secured in the mandrel with threads.

5. The plug as claimed in claim 1 wherein the baffle is formed as a part of the mandrel.

6. The plug as claimed in claim 1 wherein the one or more passageways are cylindrical.

7. The plug as claimed in claim 1 wherein the one or more passageways are tortuous.

8. A borehole system comprising:

a borehole;

a string in the borehole, the string including a plug as claimed in claim 1.

9. A method for causing an actuation via pressure comprising:

flowing fluid through a baffle of a plug as claimed in claim 1;

increasing a flow rate through the baffle to raise pressure upstream of the baffle to an actuation level without seating a member on the baffle.

10. The method as claimed in claim 9 further including flowing particles to bridge over the one or more passageways in the baffle.

11. The method as claimed in claim 9 wherein the actuation is fracturing.

12. The method as claimed in claim 9 wherein the actuation is of another tool.

13. The method as claimed in claim 9 further including returning fluid flow to a level below pressure increase and flowing fluid through the baffle.

14. A method for making a pressure differential plug as claimed in claim 1 wherein the baffle is subtractively machined in the mandrel.

15. The method as claimed in claim 14 wherein the baffle is additively manufactured with the mandrel.