Frac plug system with a setting mandrel and fluid bypass slots

Abstract

The frac plug system includes a setting mandrel, a sleeve member, a sealing member, a cone assembly, and a slip device. The setting mandrel includes a plurality of fluid bypass slots. The sleeve member includes a sleeve body with an abutment end. The setting mandrel has a first configuration without fluid flow through the frac plug system, and a second configuration with fluid flow through the frac plug system. The methods of the present invention include running the frac plug system in the first configuration and the sealing member in an extended position for a first setting stage, moving the setting mandrel to the second configuration with the sealing member in an expanded position, and then returning the setting mandrel to the first configuration for a second setting state. If the placement is wrong, the method includes removing the frac plug system in the first setting stage.

Claims

1. A frac plug system, comprising: a setting mandrel being comprised of: a mandrel body with an outer mandrel surface, a seal end and a flow end opposite said seal end; a plurality of fluid bypass slots extending longitudinally along said mandrel body from said flow end toward said seal end, each slot having an opened end at said flow end of said mandrel body and a closed end between said seal end and said flow end; and a sealing shoulder surface at said seal end, said closed end being between said sealing shoulder surface and said flow end; a sleeve member being comprised of: a sleeve body with an outer sleeve surface, an abutment end and a free end opposite said abutment end, wherein said setting mandrel has a first configuration with said seal end adjacent said abutment end of said sleeve member, and a second configuration with said closed end between said seal end and said abutment end; a sealing member being mounted around said sleeve member between said abutment end and said free end, said sealing member having an expanded position and an extended position, said sealing member in said expanded position having a diameter larger than said sealing member in said extended position; a cone assembly being mounted around said sleeve member and being in mechanical engagement with said sealing member; and a slip device being mounted around said sleeve member, said cone assembly being in sliding engagement with said slip device, wherein said second configuration of said setting mandrel corresponds to said sealing member in said expanded position, and wherein said first configuration of said setting mandrel corresponds to both said sealing member in said expanded position and said sealing member in said extended position.

2. The frac plug system, according to claim 1, wherein said setting mandrel is further comprised of an O-ring groove between said closed end and said opened end of each slot, further comprising: an O-ring set in said O-ring groove.

3. The frac plug system, according to claim 2, wherein said setting mandrel is further comprised of an additional O-ring groove between said closed end and said O-ring groove opened end of each slot, further comprising: an additional O-ring set in said additional O-ring groove.

4. The frac plug system, according to claim 1, wherein said abutment end is comprised of a conical wedge having a first end facing said sealing shoulder surface and a second end opposite said first end, said first end being wider than said second end.

5. The frac plug system, according to claim 4, said first end being in slide fit engagement with said sealing shoulder surface in said first configuration.

6. The frac plug system, according to claim 4, wherein said second end is in mechanical engagement with said sealing member so as to transition said sealing member from said extended position to said expanded position.

7. The frac plug system, according to claim 1, wherein said sealing member is between said abutment end and said cone assembly, and wherein said cone assembly is between said sealing member and said slip device.

8. The frac plug system, according to claim 7, wherein said slip device is farther from said sleeve member with said sealing member in said expanded configuration than with said sealing member in said extended configuration.

9. The frac plug system, according to claim 7, wherein said cone assembly is closer to said slip device with said sealing member in said expanded configuration than with said sealing member in said extended configuration.

10. A method for isolating a zone in a wellbore, the method comprising the steps of: running a frac plug system, according to claim 1, in a borehole with a setting tool, said setting mandrel being in said first configuration, said sealing member being in said extended position; placing said frac plug system in a location in the wellbore; transitioning said sealing member in said extended position to said sealing member in said expanded position with said frac plug system in said location; moving said setting mandrel from said first configuration to said second configuration so as to form a fluid connection through said fluid bypass slots in a first setting stage; and moving said setting mandrel from said second configuration to said first configuration so as to seal said fluid connection in a second setting stage.

11. The method for isolating, according to claim 10, wherein the step of placing said frac plug system in said location comprises the step of breaking said setting mandrel with said setting tool.

12. The method for isolating, according to claim 10, wherein the step of transitioning said sealing member in said extended position to said sealing member in said expanded position with said frac plug system comprises the steps of: applying fluid pressure on said sleeve member; and compressing said sealing member from said extended position to said expanded position.

13. The method for isolating, according to claim 12, wherein said abutment end is comprised of a conical wedge having a first end facing said sealing shoulder surface and a second end opposite said first end, said first end being wider than said second end, said first end being in slide fit engagement with said sealing shoulder surface in said first configuration, and wherein said second end is in mechanical engagement with said sealing member so as to transition said sealing member from said extended position to said expanded position, the method further comprising the step of: exerting pressure on said sealing member by said second end of said abutment end.

14. The method for isolating, according to claim 12, wherein the step of moving said setting mandrel from said first configuration to said second configuration comprises the steps of: moving said sleeve member towards said flow end of said mandrel body with said fluid pressure; and placing said sleeve member between said closed end and said flow end of said mandrel body in said first setting stage with said fluid pressure.

15. The method for isolating, according to claim 12, wherein said second end is in mechanical engagement with said sealing member so as to move said setting mandrel from said second configuration to said first configuration.

16. The method for isolating, according to claim 15, wherein the step of moving said setting mandrel from said second configuration to said first configuration comprises the steps of: applying additional fluid pressure on said seal end of said mandrel body; moving said setting mandrel towards said free end of said sleeve member; and setting said sealing shoulder surface against said abutment end of said sleeve member so as to seal said fluid connection in said second setting stage.

17. A method for correcting placement in a wellbore, the method comprising the steps of: running a frac plug system, according to claim 1, in a borehole with a setting tool, said setting mandrel being in said first configuration, said sealing member being in said extended position; placing said frac plug system in a location in the wellbore; transitioning said sealing member in said extended position to said sealing member in said expanded position with said frac plug system in said location; moving said setting mandrel from said first configuration to said second configuration so as to form a fluid connection through said fluid bypass slots in a first setting stage; and injecting fluids through said fluid bypass slots so as to remove said frac plug system.

18. The method for correcting placement, according to claim 17, wherein the step of placing said frac plug system in said location comprises the step of breaking said setting mandrel with said setting tool.

19. The method for correcting placement, according to claim 17, wherein the step of transitioning said sealing member in said extended position to said sealing member in said expanded position with said frac plug system comprises the steps of: applying fluid pressure on said sleeve member; and compressing said sealing member from said extended position to said expanded position.

20. The method for correcting placement, according to claim 17, wherein the step of injecting fluids through said fluid bypass slots so as to remove said frac plug system comprises the step of: dissolving said frac plug system, said fluids being comprised of acid.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) FIG. 1 is a side elevation view of an embodiment of the setting mandrel and fluid bypass slots of the frac plug system according to the present invention.

(2) FIG. 2 is a sectional view of an embodiment of the frac plug system according to the present invention with the setting mandrel in the first configuration and the sealing member in an extended position.

(3) FIG. 3 is a sectional view of an embodiment of the frac plug system according to the present invention with the setting mandrel in the second configuration and the sealing member in an expanded position.

(4) FIG. 4 is a sectional view of an embodiment of the frac plug system according to the present invention with the setting mandrel in the first configuration and the sealing member in an expander position.

DETAILED DESCRIPTION OF THE INVENTION

(5) Conventional frac plugs and packers set in position and set a seal in separate stages. Pre-set frac plugs are set in position and set a seal in a single stage, and there is no need for another stage. Although efficient, there is high risk of setting position and setting the seal in the wrong location accidentally. The present invention is a frac plug system that is pre-set because setting the seal remains concurrent with setting in position. The seal is pre-set. The frac plug system of the present invention has components so that setting in position is split into multiple stages, which allows quick removal if the trigger to start the setting in position was wrong. There are multiple stages for setting in position, even though setting the seal is pre-set.

(6) Referring to FIGS. 1-4, the present invention is a frac plug system 10, including a setting mandrel 20, a sleeve member 40, a sealing member 60, a cone assembly 70, and a slip device 72. FIG. 1 shows the setting mandrel 20 being comprised of a mandrel body 22, a plurality of fluid bypass slots 30, and a sealing shoulder surface 36. The mandrel body 22 has an outer mandrel surface 24, a seal end 26 and a flow end 28 opposite the seal end 26. The fluid bypass slots 30 extend longitudinally along the mandrel body 22 from the flow end 28 toward the seal end 26. Each slot 30 has an opened end 32 at the flow end 28 of the mandrel body 22 and a closed end 34 between the seal end 26 and the flow end 28. The sealing shoulder surface 36 is at the seal end 26 so that the closed end 34 is between the sealing shoulder surface 36 and the flow end 28.

(7) In some embodiments, the setting mandrel 20 is further comprised of an O-ring groove 31 between the closed end 34 and the opened end 32 of each slot 30. FIGS. 2-4 show an O-ring 35 set in the O-ring groove 31 in sliding engagement with the sleeve member 40. There can also be an additional O-ring groove 33 between the closed end 34 and the O-ring groove 31 of each slot 30 and an additional O-ring 37 set in the additional O-ring groove 33.

(8) FIGS. 2-4 show the sleeve member 40 being comprised of a sleeve body 42 with an outer sleeve surface 44, an abutment end 46 and a free end 48 opposite the abutment end 46. The setting mandrel 20 has a first configuration with the seal end 26 adjacent the abutment end 46 of the sleeve member, and a second configuration with the closed end 36 of each slot 30 between the seal end 26 and the abutment end 46. The first configuration has the sleeve member 40 mechanically engaged to the seal end 26 of the setting mandrel 20. Mechanically engaged means that the sleeve member 40 is in physical contact with the setting mandrel 20 or adjacent so that sleeve member 40 and setting mandrel can exert pressure on each other.

(9) In one embodiment, the abutment end 46 is adjacent to the seal end 26. The abutment end 46 is comprised of a conical wedge 50 having a first end 52 facing the sealing shoulder surface 36 of the setting mandrel 20 and a second end 54 opposite the first end 52. The first end 52 is wider than the second end 54 so as to set the orientation of the cone shape. FIGS. 2 and 4 show the first end 52 being in slide fit engagement with the sealing shoulder surface 36 in the first configuration.

(10) FIGS. 2-4 also show the sealing member 60 being mounted around the sleeve member 40 between the abutment end 46 and the free end 48, the cone assembly 70 being mounted around the sleeve member 40 and being in mechanical engagement with the sealing member 60, and the slip device 72 being mounted around the sleeve member 40 and being in sliding engagement with the cone assembly 70. The sealing member 60 has an expanded position (FIGS. 3-4) and an extended position (FIG. 2). The sealing member 60 in the expanded position of FIGS. 3-4 having a diameter 62 larger than the sealing member 60 in the extended position of FIG. 2. In the embodiment with the abutment end 46 being comprised of a conical wedge 50, the second end 54 is in mechanical engagement with the sealing member 60 so as to transition the sealing member 60 from the extended position to the expanded position. That is, the second end 54 is adjacent or in contact with the sealing member 60 so as to exert pressure on the sealing member 60. The pressure can compress the sealing member 60 in the extended position of FIG. 2 into the expanded position of FIGS. 3-4.

(11) In the present invention, the second configuration of the setting mandrel 20 corresponds to the sealing member 60 in the expanded position of FIG. 3. The first configuration of the setting mandrel 20 corresponds to both the sealing member 60 in the expanded position (FIG. 4) and the sealing member 60 in the extended position (FIG. 2).

(12) The sealing member 60, cone assembly 70, and slip device 72 can be conventional components of a packer to set the frac plug system 10 in position in the wellbore. The anchoring to the wellbore by the slip device 72, the sealing against the wellbore by the sealing member 60, and the sliding of the cone assembly 70 to press the slip device 72 into the wellbore are shown in FIGS. 2-4. The particular embodiments show the sealing member 60 between the abutment end 46 of the sleeve member 40 and the cone assembly 70 and the cone assembly 70 between the sealing member 60 and the slip device 72. The slip device 72 is farther from the abutment end 46 of the sleeve member 40 with the sealing member 60 in the expanded position (FIG. 2) than with the sealing member 60 in the extended position (FIGS. 3-4). The cone assembly 70 is closer to the slip device 72 with the sealing member 60 in the expanded position (FIGS. 3-4) than with the sealing member 60 in the extended position (FIG. 2).

(13) FIGS. 2-4 also show the method for isolating a zone in a wellbore as an embodiment of the present invention. The method comprises the step of running a frac plug system 10 in a borehole with a setting tool 80. FIG. 2 shows the step of running with the setting mandrel 20 in the first configuration and the sealing member 60 in the extended position. The sealing member 60 has the smaller diameter 62 so that the packer system 10 can pass through the wellbore more easily. The method of the present invention further includes placing the frac plug system 10 in a location in the wellbore. The step of placing the frac plug system in the location can comprise the step of breaking the setting mandrel 20 with the setting tool 80 (FIG. 2 attached, FIGS. 3-4 detached).

(14) FIG. 3 shows the steps of transitioning the sealing member 60 in the extended position to the sealing member 60 in the expanded position at the location and moving the setting mandrel 20 from the first configuration to the second configuration so as to form a fluid connection through the fluid bypass slots 30 in a first setting stage of setting in position. The sealing member 60, cone assembly 70, and slip device 72 anchor the packer system 10 to the wellbore, but setting in position is not yet complete. The setting mandrel 20 is not yet in a final position. The pre-set seal at the seal end 26 is not in position yet.

(15) In some embodiments, the step of transitioning the sealing member 60 in the extended position to the sealing member 60 in the expanded position includes applying fluid pressure on the sleeve member 40 so as to compress the sealing member 60 from the extended position to the expanded position. FIG. 3 shows the abutment end 46 as the conical wedge 50, so the first end 52 is in slide fit engagement with the sealing shoulder surface 36 in the first configuration and the second end 54 is in mechanical engagement with the sealing member 60 so as to transition the sealing member 60 from the extended position to the expanded position. The fluid pressure applied to the second end 54 of the abutment end 46 of the sleeve member 60 exerts force on the sealing member 60, cone assembly 70, and slip device 72 to anchor to the wellbore and slides the sleeve member 40 relative to the setting mandrel 20 to the second configuration (FIG. 3). The fluid pressure moves the sleeve member 40 towards the flow end 28 of the mandrel body 22 so as to position the sleeve member 40 between the closed end 34 of each fluid bypass slot 30 and the flow end 28 of the mandrel body 22 for the second configuration of the setting mandrel 20.

(16) At this first setting stage for setting in position, FIG. 3 shows the fluid connection through the frac plug system 10. The frac plug system 10 is anchored in place, but the seal end 26 has not yet sealed the wellbore. When the position of the frac plug system 10 within the wellbore is acceptable, the method of the present invention proceeds with the step of moving the setting mandrel 20 from the second configuration to the first configuration so as to seal the fluid connection in a second setting stage (FIG. 4).

(17) FIG. 4 shows the second setting stage with the second end 54 of the abutment end 46 in mechanical engagement with the sealing member 60 so as to move the setting mandrel 20 from the second configuration to the first configuration. The mechanical engagement is being adjacent or other contact so as to exert force on each other. The sealing member 60 is now anchored in the wellbore in the expanded position and with the slip device 72 attached to the wellbore. Thus, the sleeve member 40 is now anchored in place. The method of the present invention now includes the step of moving the setting mandrel 20 from the second configuration back to the first configuration.

(18) In some embodiments, the moving back to the first configuration comprises the step of applying additional fluid pressure on the seal end 26 of the mandrel body 22. The original amount of fluid pressure is sufficient to move the sleeve member 40 until the sleeve member 40 was anchored in place. An additional fluid pressure is now applied to move the setting mandrel 20 towards the free end 48 of the sleeve member 40. The sealing shoulder surface 36 is back against the abutment end 46 of the sleeve member 40 so as to seal the fluid connection in the second setting stage.

(19) In the second setting stage, the setting in position is completed so that the pre-set seal can form a seal across the frac plug system 10 to isolate a zone.

(20) Embodiments of the method of the present invention further include an alternative at the first setting stage of FIG. 3, when the frac plug system 10 is anchored in place, but the seal end 26 has not yet sealed the wellbore. When the frac plug system 10 is in the wrong place, the method of the present invention now includes the step of injecting fluids through the fluid bypass slots 30 so as to remove the frac plug system 10. If triggered by accident, the frac plug system 10 is no longer sealed concurrent with setting in position. Strong acid can be injected to dissolve the frac plug system 10 so that the frac plug system is removed from the wrong place in the wellbore. The fluid bypass slots 30 allow pumping acid or other additives to be delivered to the frac plug system 10.

(21) The method of this embodiment is the same steps for placing the frac plug system 10 in the location by breaking the setting mandrel 20 with the setting tool 80 and moving the setting mandrel 20 from the first configuration to the second configuration by applying fluid pressure on the sleeve member 40, moving the sleeve member 40 towards the flow end 28 of the mandrel body 22, and moving the sleeve member 40 between the closed end 34 of at least one fluid bypass slot 30 and the flow end 28 of the mandrel body 22. Instead of applying additional fluid pressure to move the setting mandrel 20 to the now anchored sleeve member 40, this alternative embodiment injects strong acid to dissolve components of the frac plug system 10 so that the frac plug system 10 is removed from the location within the wellbore.

(22) The present invention provides a frac plug system to isolate zones in a wellbore. The frac plug system is pre-set because no additional stage is needed to set the seal. A frac ball is not dropped to form the seal. There is no ball seat or other valve seat to accommodate a frac ball in the frac plug system of the present invention. The time, components, and risk of a frac ball for form the seal is avoided. Additionally, the risk of accidental triggering the frac plug with a pre-set frac ball is also avoided. The present invention further includes the frac plug system having multiple stages for setting in position to isolate the wellbore. Despite this pre-setting of the seal, the setting in position includes multiple stages. Before all stages of setting in position are complete, it is possible to remove the frac plug system by injecting strong acid to dissolve components of the frac plug system. If the frac plug system was accidentally triggered in the wellbore to set position, there is no longer an automatic set position and set seal that cannot be easily removed.

(23) Embodiments of the present invention include a frac plug system having a setting mandrel with fluid bypass slots and a sleeve member. These components are positioned and have structures for fluid connection relationships so that fluid pressure variation controls isolating a zone. Also, the fluid pressure actuation of the setting mandrel and sleeve member allows the frac plug system to be removed at a first setting stage before a second setting stage.

(24) The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated structures, construction and method can be made without departing from the true spirit of the invention.