WO2019212496A1

WO2019212496A1 - Setting frac plugs

Info

Publication number: WO2019212496A1
Application number: PCT/US2018/030245
Authority: WO
Inventors: Michael L. Fripp; Zachary William WALTON; Tyler Joseph NORMAN; Matthew James MERRON
Original assignee: Halliburton Energy Services, Inc.
Priority date: 2018-04-30
Filing date: 2018-04-30
Publication date: 2019-11-07

Abstract

A method includes positioning frac sleeve within an oilfield tubular, wherein the frac sleeve includes a plug seat. The method includes using an explosive forming process to expand the frac sleeve outward into an interference fit with the oilfield tubular. Using an explosive forming process can include deforming both the frac sleeve and the oilfield tubular.

Description

SETTING FRAC PLUGS

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present disclosure relates to gas and oil production, and more particularly to frac plugs for use with down hole tools for fracking.

2. Description of Related Art

Traditional frac plugs use slips that bite into the casing or other oilfield tubular after compression with a setting tool. Once a frac plug is set, the casing up well from the plug can be perforated, e.g., using explosive charges from a gun tool. The resulting perforations in the casing can be used for hydraulic fracturing a frac zone from above the plug, and for subsequent production from the frac zone.

The conventional techniques have been considered satisfactory for their intended purpose. However, there is an ever present need for improved setting of frac plugs and the like. This disclosure provides a solution for this need.

BRIEF DESCRIPTION OF THE DRAWINGS

So that those skilled in the art to which the subject disclosure appertains will readily understand how to make and use the devices and methods of the subject disclosure without undue experimentation, preferred embodiments thereof will be described in detail herein below with reference to certain figures, wherein:

Fig. 1 is a schematic cross-sectional side elevation view of an exemplary embodiment of a system constructed in accordance with the present disclosure, showing the frac sleeve positioned within a well casing;

Fig. 2 is a schematic cross-sectional side elevation view of the system of Fig. 1, showing the frac sleeve and well casing after explosive forming;

Fig. 3 is a schematic cross-sectional side elevation view of the system of Fig. 1, showing a ball seated in the plug seat of the frac sleeve;

Fig. 4 is a schematic perspective view of an exemplary embodiment of a frac sleeve in accordance with the present disclosure, showing a plurality of discrete point dimples formed in the frac sleeve;

Fig. 5 is a schematic perspective view of an exemplary embodiment of a frac sleeve in accordance with the present disclosure, showing a plurality of full annular dimples formed in the frac sleeve;

Fig. 6 is a schematic cross-sectional side elevation view of a portion of the system of Fig. 1, showing the deformation in both the frac sleeve and the well casing;

Fig. 7 is a schematic cross-sectional side elevation view of a portion of another exemplary embodiment of the system of Fig. 1, showing both the frac sleeve and the well casing perforated; Fig. 8 is a schematic cross-sectional side elevation view of a portion of another exemplary embodiment of the system of Fig. 1, showing outward swelling of both the frac sleeve and the well casing;

Fig. 9 is a schematic cross-sectional side elevation view of a portion of another exemplary embodiment of the system of Fig. 1, showing a grappling hook fired through the frac sleeve and well casing;

Fig. 10 is a schematic cross-sectional side elevation view of a portion of another exemplary embodiment of the system of Fig. 1, showing a frac sleeve with variable wall thickness to facilitate the explosive forming process; and

Fig. 11 is a schematic cross-sectional side elevation view of a well system incorporating a plurality of frac sleeves like that of Fig. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawings wherein like reference numerals identify similar structural features or aspects of the subject disclosure. For purposes of explanation and illustration, and not limitation, a partial view of an exemplary embodiment of a frac sleeve in accordance with the disclosure is shown in Fig. 1 and is designated generally by reference character 100. Other embodiments of frac sleeves in accordance with the disclosure, or aspects thereof, are provided in Figs. 2-11, as will be described. The systems and methods described herein can be used to set frac plugs for hydraulic fracturing, e.g., to produce hydrocarbon fluids from earth formations.

The frac sleeve 100 is positioned within a well casing 102, which itself is positioned within an annulus 104 of a well bore 106 in an earth formation 108. While shown and described herein in the exemplary context of the well casing 102, those skilled in the art will appreciate that the systems and methods disclosed herein can be applied to any jointed tubular within a wellbore and includes casing, production tubing, drill tubing, liners, and any other suitable jointed oilfield tubular. The frac sleeve 100 includes a plug seat 110, however the frac sleeve can also be configured to receive any other suitable occlusion. An explosive forming process is used to expand the frac sleeve 100 outward to anchor the frac sleeve 100 to the well casing 102, e.g., by forming an interference fit with the well casing 102, to set the frac sleeve 100 in place within the well casing 102. An explosive forming tool 112 can be positioned inside the frac sleeve 100 as shown in Fig. 1, and explosive charges 114 can be fired to impact against an inner surface 116 of the frac sleeve 100 with projectiles and/or a jet of fluid as indicated schematically by the arrows in Fig. 2. The explosive forming tool 112 and frac sleeve 100 can be positioned within the well casing 102 using any suitable technique such as lowering, pumping, conveying, and/or tractoring. Those skilled in the art will readily appreciate that the explosive forming include using tools that incorporate a flammable solid as well as those that incorporate an explosive material, e.g., Hazard Class 1 and Hazard Class 4 materials.

With continued reference to Fig. 2, the explosive forming projectiles/and or jets form outward extending dimples 118 in the frac sleeve 100. As shown in Fig. 4, the dimples 118 can be discrete point dimples 118 in the frac sleeve 100. As shown in Fig. 5, it is also contemplated that the dimples 118 can be full annular dimples in the frac sleeve 100 extending circumferentially around the frac sleeve 100.

Using an explosive forming process can include deforming both the frac sleeve 100 and in the well casing 102. As shown in Fig. 6, forming the dimples 118 (whether they are discrete point dimples as shown in Fig. 4, full annular dimples as shown in Fig. 5, or any other suitable shape of dimples), can include forming corresponding discrete point, annular, or other shaped dimples 120 in the well casing 102. The well casing 102 can be elastically and/or plastically deformed. The explosive forming process can deform the inner surface 116 and outer surface 122 of the frac sleeve 100, and can also deform an inner surface 124 and an outer surface 126 of the well casing 102. After the explosive forming, the dimples 120 can manifest on the exterior of the well casing 102. The outer surface 122 of the frac sleeve 100 can optionally include a texture and/or coating configured to increase axial force holding of the frac sleeve 100 to the well casing 102.

Referring to Fig. 7, using an explosive forming process to expand the frac sleeve 100 outward into an interference fit with the well casing 102 can include perforating the frac sleeve 100, and even perforating the well casing 102. Fig. 7 shows a perforation 128 formed in the frac sleeve 100 as well as a corresponding perforation 130 formed in the well casing 102. The interference fit in this case is formed when generally triangular perforation petals 132 of the perforation 128 interlock with generally triangular perforation petals 134 of the perforation 130. It is also contemplated that only one of the frac sleeve 100 and well casing 102 can be perforated. Hydraulic fracturing and/or production of fluid can be performed through the perforations 128 and 130. The perforations 128 and 130 can be formed in lieu of or in addition to the dimples 118 described above, and the difference between forming dimples or perforations is based on the size and speed of the explosive forming projectile and/or jet. For example, lower speed projectiles, blunter shaped projectiles, and larger diameter projectiles are more likely to create a dimple, whereas higher speed projectiles, blunter shaped projectiles, and larger diameter projectiles are more likely to create a perforation. Changing the shape, explosive speed, the liner, the case, and the standoff between the explosive forming tool 112 and the frac sleeve 100 changes the shape, bluntness, and/or speed of the perforating jet and/or projectile. Depending on the strain-to-limit failure of the frac plug 100 and of the well casing 102, the actual interference may be a combination of dimpling, perforating, and explosive forming, e.g. swelling as shown in Fig. 8. For example, the frac plug 100 may be perforated while the well casing 102 is dimpled.

With reference now to Fig. 8, using the explosive forming process to expand the frac sleeve 100 outward into an interference fit with the well casing 102 can include a less focused swelling than in the case of the dimples 118 described above. For example if the chargers and/or projectiles from the explosive forming tool 112 (shown in Fig. 1) are less focused, a swelling 136 can be formed in the frac sleeve 100 and a corresponding swelling 138 can be formed in the well casing 102. The swellings 136 and 138 are similar to the dimples 118 and 120 described above and can be discrete points, fully annular, or of any other suitable shape, however they are more spread out than the dimples 118 and 120.

With reference now to Fig. 9, using an explosive forming process to expand the frac sleeve 100 into an interference fit with the well casing 102 can include firing a grappling hook 140 through the frac sleeve 100 and through the well casing 102, e.g., wherein a barb 142 of the grappling hook 140 passes the outer surface 126 of the well casing 102, a head 144 of the grappling hook 140 remains inside the inner surface 116 of the frac sleeve 100, and a shaft 146 of the grappling hook connects the barb 142 and the head 144 to secure the frac sleeve 100 in place within the well casing 100. The grappling hook 140 can be used in addition to or in lieu of dimples 118 and 120, perforations 128 and 130, and swellings 136 and 138. The barb 142 can have the same diameter as the shaft of the grappling hook 140. In another aspect, the grappling hook 140 can be conical with a continuously varying diameter (e.g. the shaft 146 and head 144 can optionally be omitted). As shown in Fig. 10 and in accordance with any of the foregoing embodiments, the frac sleeve 100 prior to explosive forming can include a variable wall thickness, e.g., with a thinner or weakened area 148, configured to enhance the interference fit. For example, the frac sleeve 100 prior to explosive forming can have pre-made circumferential ridges as shown in Fig. 10. The frac sleeve 100 can include a dissolvable material, e.g., a dissolvable metal alloy, configured to degrade in wellbore fluids, e.g., so the frac sleeve 100 can dissolve after hydraulic fracturing is completed.

With reference now to Fig. 3, an elastomer seal 150 can be confined between the frac sleeve 100 and the well casing 102 after the explosive forming that is indicated in Figs. 1 and 2. It is also contemplated that the outer diameter of the frac sleeve 100 can be coated with a hard coating such as a carbide coating. Fully annular dimples 118, as shown in Fig. 5, are less likely to give rise to a need for an elastomer seal 150 than discrete point dimples 118 as shown in Fig. 4, to ensure sealing between the frac plug 100 and the well casing 102. A ball 152 or other suitable plug can be received in the plug seat 110 to seal off the well casing 102 down well from the ball 152 and elastomer seal 150 (the portion of the well casing 102 below the ball 152 and elastomer seal 150 as oriented in Fig. 3) for hydraulic fracturing a predetermined frac zone, e.g., up well from or above the ball 152 and elastomer seal 150. An elastomer coating or other suitable coating can be included on the outer surface of the ball 152 to facilitating sealing the ball 152 against the plug seat 110, e.g., to create a water tight seal. Those skilled in the art will readily appreciate that in Figs. 1-3 the up well direction is upward in the figures, and the down well direction is downward in the figures, however other orientations are possible, e.g., in a horizontal section of a well bore where the up well direction leads closer to the surface as one travels along the well bore. Explosive forming pressure on the ball 152, e.g. from the up well direction, can be used to enhance elastomer engagement of the elastomer seal 150 with the well casing 102, and/or pressure on the ball 152 can be used to swell the well casing 102 by outward pressure from the elastomer seal 150 as indicated by the large arrows in Fig. 3. The resulting swelling can be as shown in Fig. 8 for example. Using explosive forming can include forming an interference fit, e.g., with dimples 118 and 120 or any of the other types of interference fit disclosed herein, in at least one position up well and/or down well of a seal between the frac sleeve 100 and the well casing 102. For example, as shown in in Fig. 3, the dimples 118 are formed both up well of and down well of the seal that includes the ball 152 sealing against the plug seat 110 and that includes the elastomer seal 150 sealing between the well casing 102 and the frac sleeve 100.

It may be advantageous depending on the application to use explosive forming to create the interference fit only up well of the plug seat 110 and (if applicable) the elastomer seal 150 in case perforations are formed in the well casing 102 that could undermine isolating frac zones from one another if there were perforations down well of where the ball 152, the frac sleeve 100, and the well casing 102 are sealed. It is also contemplated that the plug seat 110 can be on the side of the frac sleeve 100 closest to the surface of the wellbore.

With reference now to Fig. 11, positioning the frac sleeve 100 within the well casing 102 can include positioning a plurality of frac sleeves 100 within the well casing 102, spaced axially apart from one another. An explosive forming process can be used on each of the frac sleeves 100 for expanding each of the frac sleeves 100 outward into an interference fit with the well casing 102 as described above. Each of the frac sleeves 100 can have a plug seat 110 that is sized differently from the others, wherein the plug seat 110 with the smallest opening being the lower most, the plug seat 110 with the largest opening being the upper most, and so forth, as oriented in Fig. 11. The appropriately sized balls 152 can be dropped in the appropriate order to seal off different zones of well casing 102 for hydraulic fracturing of the earth formation 108 in a zone by zone manner. In the explosive forming processes described above, it can be noted that hydraulic fracturing utilizes explosives as part of the preparation of a frac zone, and that some of the explosive energy can be used to set the frac plugs 100 as described above, e.g. with reference to Fig. 8. Using explosive forming as disclosed herein can reduce the cost of setting and sealing a frac plug relative to traditional techniques.

Accordingly, as set forth above, the embodiments disclosed herein may be implemented in a number of ways. For example, in general, in one aspect, the disclosed embodiments relate to a method of setting a frac plug. The method includes positioning a frac sleeve within a oilfield tubular, wherein the frac sleeve is configured to receive an occlusion. The method includes using an explosive forming process to expand the frac sleeve outward and anchor the frac sleeve to the oilfield tubular.

In general, in another aspect, the disclosed embodiments relate to a system. The well arrangement includes a frac sleeve within a oilfield tubular, wherein the frac sleeve is anchored to the oilfield tubular by any process described herein.

In general, in another aspect, the disclosed embodiments relate to a system including a frac sleeve configured to engage an oilfield tubular for fracking. An explosive setting tool is within the frac sleeve, wherein the frac sleeve and explosive setting tool are configured to form an interference fit between the frac sleeve and the oilfield tubular by explosive forming upon activation by the explosive setting tool. In accordance with any of the foregoing embodiments, using an explosive forming process can include deforming both the frac sleeve and the oilfield tubular.

In accordance with any of the foregoing embodiments, using an explosive forming process can include deforming an inner surface and an outer surface of the oilfield tubular.

In accordance with any of the foregoing embodiments, expanding the frac sleeve outward can include forming a plurality of outward extending, discrete point dimples in the frac sleeve. Forming the plurality of outward extending, discrete point dimples in the frac sleeve can include forming the discrete point dimples in the oilfield tubular.

In accordance with any of the foregoing embodiments, expanding the frac sleeve outward can include forming at least one full annular dimple in the frac sleeve. Forming at least one full annular dimple in the frac sleeve can include forming the at least one full annular dimple in the oilfield tubular.

In accordance with any of the foregoing embodiments, the method can include confining an elastomer seal between the frac sleeve and the oilfield tubular, and receiving a ball in the plug seat to seal off the oilfield tubular down well from the ball and elastomer seal for hydraulic fracturing a predetermined frac zone. The method can include using pressure on the ball to enhance elastomer engagement of the elastomer seal, and/or swelling the oilfield tubular by outward pressure from the elastomer seal.

In accordance with any of the foregoing embodiments, using an explosive forming process to expand the frac sleeve outward and anchoring the frac sleeve to the oilfield tubular can include perforating the frac sleeve. Perforating the frac sleeve can include perforating the oilfield tubular.

In accordance with any of the foregoing embodiments, using an explosive forming process to expand the frac sleeve the oilfield tubular can include firing a grappling hook through the oilfield tubular. In accordance with any of the foregoing embodiments, the frac sleeve can include a dissolvable material configured to degrade in wellbore fluids.

In accordance with any of the foregoing embodiments, positioning the frac sleeve within the oilfield tubular can include positioning a plurality of frac sleeves within the oilfield tubular, spaced axially apart from one another, and using an explosive forming process can include expanding each of the frac sleeves in the plurality of frac sleeves outward and anchoring the frac sleeves to the oilfield tubular.

In accordance with any of the foregoing embodiments, using explosive forming can include firing a projectile against an inner surface of the frac sleeve. It is also contemplated that using explosive forming can include firing a jet of fluid against an inner surface of the frac sleeve.

In accordance with any of the foregoing embodiments, using explosive forming can include forming an interference fit in at least one position up well of and/or down well of a seal between the frac sleeve and the oilfield tubular.

In accordance with any of the foregoing embodiments, the frac sleeve can include a variable wall thickness configured to enhance the interference fit.

In accordance with any of the foregoing embodiments, an outer surface of the frac sleeve can include a texture configured to increase axial force holding of the frac sleeve.

The methods and systems of the present disclosure, as described above and shown in the drawings, provide for setting frac plugs with superior properties including ease of use and manufacture. While the apparatus and methods of the subject disclosure have been shown and described with reference to preferred embodiments, those skilled in the art will readily appreciate that changes and/or modifications may be made thereto without departing from the scope of the subject disclosure.

Claims

What is claimed is:

1. A method of setting a frac plug comprising:

positioning a frac sleeve within an oil field tubular, wherein the frac sleeve is configured to receive an occlusion; and

using an explosive forming process to expand the frac sleeve outward and anchor the frac sleeve to the oilfield tubular.

2. The method as recited in claim 1, wherein using an explosive forming process includes deforming both the frac sleeve and the oilfield tubular, and optionally,

wherein using an explosive forming process includes deforming an inner surface and an outer surface of the oilfield tubular.

3. The method as recited in any preceding claim, wherein expanding the frac sleeve outward includes forming a plurality of outward extending, discrete point dimples in the frac sleeve, and optionally,

wherein forming the plurality of outward extending, discrete point dimples in the frac sleeve includes forming the discrete point dimples in the oilfield tubular.

4. The method as recited in any preceding claim, wherein expanding the frac sleeve outward includes forming at least one full annular dimple in the frac sleeve, and optionally, wherein forming at least one full annular dimple in the frac sleeve includes forming the at least one full annular dimple in the oilfield tubular.

5. The method as recited in any preceding claim, further comprising confining an elastomer seal between the frac sleeve and the oilfield tubular, and receiving a ball in the plug seat to seal off the oilfield tubular down well from the ball and elastomer seal for hydraulic fracturing a predetermined frac zone, and optionally,

using pressure on the ball to enhance elastomer engagement of the elastomer seal, and optionally,

further comprising swelling the oilfield tubular by outward pressure from the elastomer seal.

6. The method as recited in any preceding claim, wherein using an explosive forming process to expand the frac sleeve outward and anchoring the frac sleeve to the oilfield tubular includes perforating the frac sleeve, and optionally,

wherein perforating the frac sleeve includes perforating the oilfield tubular.

7. The method as recited in any preceding claim, wherein using an explosive forming process to expand the frac sleeve includes firing a grappling hook through the oilfield tubular.

8. The method as recited in any preceding claim, wherein the frac sleeve includes a dissolvable material configured to degrade in wellbore fluids.

9. The method as recited in any preceding claim, wherein positioning the frac sleeve within the oilfield tubular includes positioning a plurality of frac sleeves within the oilfield tubular, spaced axially apart from one another, and wherein using an explosive forming process includes expanding each of the frac sleeves in the plurality of frac sleeves outward to anchor the frac sleeves to the oilfield tubular.

10. The method as recited in any preceding claim, wherein using explosive forming includes firing a projectile against an inner surface of the frac sleeve.

11. The method as recited in any preceding claim, wherein using explosive forming includes firing a jet of fluid against an inner surface of the frac sleeve.

12. The method as recited in any preceding claim, wherein using explosive forming includes forming an interference fit in at least one position up well of and/or down well of a seal between the frac sleeve and the oilfield tubular.

13. The method as recited in in any preceding claim, wherein the frac sleeve includes a variable wall thickness configured to enhance the interference fit.

14. The method as recited in any preceding claim, wherein an outer surface of the frac sleeve includes a texture configured to increase axial force holding of the frac sleeve.

15. A system comprising:

a frac sleeve configured to engage an oilfield tubular for fracking; and

an explosive setting tool within the frac sleeve, wherein the frac sleeve and explosive setting tool are configured to form an interference fit between the frac sleeve and the oilfield tubular by explosive forming upon activation by the explosive setting tool.