Pump down well stimulation

Abstract

A method and apparatus for perforating a well casing wherein the apparatus comprises an elongate body extending between first and second ends wherein the elongate body is physically unconnected to the surface and the elongate body includes at least one casing perforating charge and a controller therein. The controller is operable to activate at least one of the at least one casing perforating charge to perforate the casing at a predetermined location along the well. The method comprises pumping the body down a wellbore, determining a location of the body along the wellbore of the body and activating through a controller at least one casing perforating charge at a predetermined discharge location along the wellbore.

Description

BACKGROUND OF THE INVENTION1. Field of Invention

[0001] The present invention relates generally to petroleum production and in particular to a method and apparatus for stimulating a well.2. Description of Related Art

[0002] In hydrocarbon production, it is frequently desirable to select which zone of the wellbore is to be opened for production or to stimulate one or more zones of the well to increase production of that zone from time to time. One current method of stimulating a portion of the well is through the use of hydraulic fracturing or fracing. During fracing, it that is necessary to isolate all other zones and to hydraulically couple the desired zone to the interior of a production string to enable the producing string to provide fracing material to be the desired zone.

[0003] One conventional method of opening forming perforations in a casing for fracing operations is through the use of one of several methods. In particular, methods known as plug and perf utilize a bridge plug pumped down the casing with a perforating gun. The plug is set and then uses the perforating gun to pierce the casing in that zone and the zone pressurized with the fracture stimulation treatment. The process is then repeated moving up the well until complete. One difficulty with conventional plug and perf operations is that after the fracing operation is complete, the plugs must be removed, which is conventionally accomplished through milling them out. Additionally, as the bridge plug and perforating gun are lowered into the well on a wireline, the wireline must be returned to the surface for reloading which takes additional time between zones.SUMMARY OF THE INVENTION

[0004] According to one embodiment, there is disclosed an apparatus for perforating a well casing comprising an elongate body extending between first and second ends wherein the elongate body is physically unconnected to the surface, the elongate body including at least one casing perforating charge and a controller therein wherein the controller is operable to activate at least one of the at least one casing perforating charge to perforate the casing at a predetermined location along the well.

[0005] The apparatus may further include a seal for sealing below the discharge location with an isolating device. The isolating device may be included in the body. The isolating device may include an internal setting tool. The setting tool may be hydraulic. The setting tool may utilize an explosive charge. The setting tool may utilize hydrostatic pressure and an atmospheric chamber.

[0006] At least one degradable element of the body so as to permit removal. The at least one degradable element may be dissolvable. The at least one degradable element may be selected from the group comprising dissolvable plastics and metals. The at least one degradable element may be selected to decompose after a predetermined period of time.

[0007] The controller may be configured to detect and count casing collars passed by the body within the casing. The controller may include a connected sensor adapted to sense the presence of a casing collar. The sensor may detect the thickness of the casing collar. The sensor may detect the crack between casing collar edges.

[0008] The controller may be configured to detect the depth of the body within the wellbore. The controller may be configured to measure the depth form surface. The controller may be configured to measure the depth from a corresponding apparatus. The controller may measure depth utilizing sonar. The controller may receive a depth measurement from surface. The controller may measure depth to a next obstruction utilizing sonar. The controller may measure depth utilizing ultrasound. The controller may measure depth utilizing pressure pulses to surface.

[0009] The apparatus may include at least one shot segment containing the at least one casing perforating shot and a controller segment. The apparatus may include a plurality of shot segments. Each shot segment may be selectably decouplable from a subsequent shot segment. Each shot segment may be decoupled in response to a signal from the controller.

[0010] According to a further embodiment, there is disclosed an apparatus for stimulating a well comprising an elongate body extending between first and second ends and connectable to a casing perforating device, a first seal engaging cone secured around the elongate body, a second moveable seal engaging cone slidably locatable around the elongate body and a seal element between the first and second cones.

[0011] The second cone may include a pair of opposed retractable shoes adapted to selectively cover a rear actuating surface of the second cone. The retractable shoes may be retained in an extended positon by a frangible ember.

[0012] The apparatus may include a bypass passage therethrough. The bypass may include a check valve adapted to prevent flow therethrough in a downward direction.

[0013] According to a further embodiment, there is disclosed a method for perforating well casing comprising pumping a body down a wellbore, wherein the body is physically unconnected to the surface, determining a location of the body along the wellbore of the body and activating through a controller at least one casing perforating charge at a predetermined discharge location along the wellbore.

[0014] Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In drawings which illustrate embodiments of the invention wherein similar characters of reference denote corresponding parts in each view,

[0016] FIG. 1 is a cross-sectional view of a wellbore having a casing and a casing perforating apparatus therein.

[0017] FIG. 2 is a perspective view of an apparatus for perforating a casing according to a first embodiment of the present disclosure.

[0018] FIG. 3 is a cross-sectional view of the casing perforating apparatus of FIG. 2.

[0019] FIG. 4 is a cross-sectional view of the isolating section of the apparatus of FIG. 2 at an initial position.

[0020] FIG. 5 is a cross-sectional view of a setting tool of the isolating section of FIG. 4 at an activated position.

[0021] FIG. 6 is a perspective view of an apparatus for perforating a casing according to a further embodiment of the present disclosure.

[0022] FIG. 7 is a cross-sectional view of apparatus of FIG. 6.

[0023] FIG. 8 is an isolated cross sectional view of one perforating segment of the apparatus of FIG. 6 at an initial position.

[0024] FIG. 9 is a cross sectional view of the perforating segments of the apparatus of FIG. 6 at an activated or extended position spaced out along the wellbore.DETAILED DESCRIPTION

[0025] Referring to FIG. 1, a wellbore 10 is drilled into the ground 8 to a production zone 6 by known methods. The production zone 6 may contain a horizontally extending hydrocarbon bearing rock formation or may span a plurality of hydrocarbon bearing rock formations such that the wellbore 10 has a path designed to cross or intersect each formation. As illustrated in FIG. 1, the wellbore includes a vertical section 12 having a valve assembly or Christmas tree 14 at a top end thereof and a bottom or production section 16 which may be horizontal or angularly oriented relative to the horizontal located within the production zone 6. The casing 20 is formed of a plurality of casing 22 sections connected at collars 24 as are commonly known. After the wellbore 10 is drilled and casing 20 located therein according to known methods, the wellbore may be stimulated during a fracing operation as the operation is commonly referred to by pumping down a stimulation apparatus 30 as is further set out and described below. The stimulation apparatus 30 is physically unconnected to the surface through a tool string or wireline as are commonly known and is completely translated down the casing by pumping fluids through the casing in an operation commonly known as pump down. The apparatus 30 that is adapted to perforate the wellbore at a one or more predetermined locations or depths therealong.

[0026] Turning now to FIG. 2, the apparatus 30 comprises an elongate body extending between first and second ends, 32 and 34, respectively. The apparatus includes at least one casing perforating shot 36 located therein and a controller 40 adapted to control the discharge of the casing perforating shots 36. The casing perforating shots 36 may be of any known type and may be permanently or removably located in the apparatus. In particular, the casing perforating shots may comprise cartridges threadably or otherwise located within bores in the exterior of the apparatus. The elongate body may be further divided into a control section 40 and one or more shot segments 60. With reference to FIGS. 2 through 5, the apparatus may include a single shot segment wherein as illustrated in FIGS. 6 through 9, a plurality of shot segments may be utilized.

[0027] The controller 40 may include a battery and be formed of any known control circuitry, processor or the like and including all required accessories, including memory, data storage, batteries and signal transmitter / receivers. The controller may include an associated sensor 42 for determining the location of the apparatus within the well. The sensor 42 may be selected to sense a relative position of the apparatus within the well by counting casing collars (as are well known) or by determining the depth of the apparatus 30 within the wellbore. In particular the sensor 42 may be selected to count collars as a casing collar locator. The casing collar locator may be selected to detect casing thickness and identify thicker portion corresponding to a casing collar. Alternatively, the casing collar locator may identify cracks or metal separation identifying the connection between casing sections, including without limitation, a hall effect, ultrasound or magnetic flux sensors. It will be appreciated that any other casing collar locator methods may be utilized as well including, without limitation, a mechanical measurement of distance including a surveyors wheel, optical sensors measuring scattered return of light from the crack or seam or any combination of methods and devices.

[0028] In some embodiments, the sensor 42 may be selected to provide information to the controller 40 as to identify the depth of the apparatus 30 down the well. In particular, the sensor may comprise an ultrasound or sonar sensor configured to measure the distance of the apparatus 30 to an obstruction below the apparatus including, without limitation, the bottom of the well, a plug or isolation device downhole of the apparatus, including, a formerly located apparatus 30. Furthermore, a depth reader at the surface or other location adapted to read the depth of the apparatus 30 and send on or more signals, including without limitation, sonar, ultrasound, pressure pulse or other fluid communication signal or vibration or electric signal through the casing to the apparatus 30 to deploy perforating segments or engage the isolation section 70 as will be more fully described below. The controller 40 may also measure the speed of the apparatus 30 within the casing and time to further determine the proper location to discharge the shots 36. In such embodiments, an induction or magnetic flux device may be utilized in conjunction with a reader device to measure decay in the induction or magnetic flux so as to determine the apparatus speed.

[0029] In operation, the apparatus 30 is located in a casing 22 and disconnected from surface by a tool string, wireline or any other physical connection. Thereafter the apparatus 30 is pumped along with a fluid down the casing 22 and operates automatously under the control of the controller 40. The controller 40 in response to determining that the apparatus 30 is at the correct location down the well causes at least one of the shots 36 to discharge perforating the wellbore. Optionally, at a further location down the wellbore, the controller 40 may actuate an isolation device 70 as will be further described below to isolate the casing below the location of the casing perforations formed by the shot. Thereafter, increased fluid may be pumped down the casing to stimulate the well. As illustrated, the controller 40 and sensor may be located within the isolation section 70.

[0030] Turning to FIGS. 4 and 5, the isolation device is illustrated. It will be appreciated that although one isolation device style is illustrated herein, any other isolation device may also be utilized as are known. In particular as illustrated in FIGS. 4 and 5, the isolation device includes a top cone 72 and a moveable bottom cone 74 with a seal element 76 therebetween. The seal element 76 may be of any expandable material as are know and may optionally include one or more grip enhancing inserts therein or other surface treatments to enhance gripping on the casing. The isolation device may include at least one bypass passage 92 extending therethrough with a captured ball 92 therein adapted to cover the passage so as to prevent the flow in a downward direction therethrough as illustrated in FIG. 5 or uncovered so as to permit fluid flow upward through eh apparatus as illustrated in FIG. 4.

[0031] The apparatus 30 may be formed of any suitable material, including, without limitation, metals, plastics composite materials or ceramics. Optionally one or more of the elements of the apparatus 30 may be formed of a material that is degradable or dissolvable so as to permit the apparatus to be removed from its set location within the casing without milling. In particular, one or more of the elements of the apparatus may be formed of a dissolvable metal, a dissolvable plastic or the like, including without limitation thermoplastics, magnesium alloys, aluminium alloys and composite materials that are dissolvable and / or millable.

[0032] Turning now to FIGS. 6 through 9, the apparatus 30 may be formed with a plurality of shot segments 60, each including at least one casing perforating shot 36. As illustrated, each shot segment 60 may include a wedge 62 or other casing engaging member adapted to be extended into engagement with the casing and a releasable connector 64 to the next shot segment. In response to a signal from the controller 40, a wedge 62 of the top most shot segment 60 to engage the wedge 62, release the connector 64 and discharge the shots at any combination of timing. It will be appreciated that by sequentially releasing the shot segments, a plurality of casing perforations at a plurality of locations along the wellbore may be achieved. After forming such perforations, the controller 40 may engage the isolation device 70 to isolate the wellbore above the isolation device permitting stimulating. Optionally, isolation may occur prior to perforating.

[0033] While specific embodiments have been described and illustrated, such embodiments should be considered illustrative only and not as limiting the disclosure as construed in accordance with the accompanying claims.

Examples

Embodiment Construction

[0025]Referring to FIG. 1, a wellbore 10 is drilled into the ground 8 to a production zone 6 by known methods. The production zone 6 may contain a horizontally extending hydrocarbon bearing rock formation or may span a plurality of hydrocarbon bearing rock formations such that the wellbore 10 has a path designed to cross or intersect each formation. As illustrated in FIG. 1, the wellbore includes a vertical section 12 having a valve assembly or Christmas tree 14 at a top end thereof and a bottom or production section 16 which may be horizontal or angularly oriented relative to the horizontal located within the production zone 6. The casing 20 is formed of a plurality of casing 22 sections connected at collars 24 as are commonly known. After the wellbore 10 is drilled and casing 20 located therein according to known methods, the wellbore may be stimulated during a fracing operation as the operation is commonly referred to by pumping down a stimulation apparatus 30 as is further set o...

BACKGROUND OF THE INVENTION1. Field of Invention

[0001] The present invention relates generally to petroleum production and in particular to a method and apparatus for stimulating a well.2. Description of Related Art

[0002] In hydrocarbon production, it is frequently desirable to select which zone of the wellbore is to be opened for production or to stimulate one or more zones of the well to increase production of that zone from time to time. One current method of stimulating a portion of the well is through the use of hydraulic fracturing or fracing. During fracing, it that is necessary to isolate all other zones and to hydraulically couple the desired zone to the interior of a production string to enable the producing string to provide fracing material to be the desired zone.

[0003] One conventional method of opening forming perforations in a casing for fracing operations is through the use of one of several methods. In particular, methods known as plug and perf utilize a bridge plug pumped down the casing with a perforating gun. The plug is set and then uses the perforating gun to pierce the casing in that zone and the zone pressurized with the fracture stimulation treatment. The process is then repeated moving up the well until complete. One difficulty with conventional plug and perf operations is that after the fracing operation is complete, the plugs must be removed, which is conventionally accomplished through milling them out. Additionally, as the bridge plug and perforating gun are lowered into the well on a wireline, the wireline must be returned to the surface for reloading which takes additional time between zones.SUMMARY OF THE INVENTION

[0004] According to one embodiment, there is disclosed an apparatus for perforating a well casing comprising an elongate body extending between first and second ends wherein the elongate body is physically unconnected to the surface, the elongate body including at least one casing perforating charge and a controller therein wherein the controller is operable to activate at least one of the at least one casing perforating charge to perforate the casing at a predetermined location along the well.

[0005] The apparatus may further include a seal for sealing below the discharge location with an isolating device. The isolating device may be included in the body. The isolating device may include an internal setting tool. The setting tool may be hydraulic. The setting tool may utilize an explosive charge. The setting tool may utilize hydrostatic pressure and an atmospheric chamber.

[0006] At least one degradable element of the body so as to permit removal. The at least one degradable element may be dissolvable. The at least one degradable element may be selected from the group comprising dissolvable plastics and metals. The at least one degradable element may be selected to decompose after a predetermined period of time.

[0007] The controller may be configured to detect and count casing collars passed by the body within the casing. The controller may include a connected sensor adapted to sense the presence of a casing collar. The sensor may detect the thickness of the casing collar. The sensor may detect the crack between casing collar edges.

[0008] The controller may be configured to detect the depth of the body within the wellbore. The controller may be configured to measure the depth form surface. The controller may be configured to measure the depth from a corresponding apparatus. The controller may measure depth utilizing sonar. The controller may receive a depth measurement from surface. The controller may measure depth to a next obstruction utilizing sonar. The controller may measure depth utilizing ultrasound. The controller may measure depth utilizing pressure pulses to surface.

[0009] The apparatus may include at least one shot segment containing the at least one casing perforating shot and a controller segment. The apparatus may include a plurality of shot segments. Each shot segment may be selectably decouplable from a subsequent shot segment. Each shot segment may be decoupled in response to a signal from the controller.

[0010] According to a further embodiment, there is disclosed an apparatus for stimulating a well comprising an elongate body extending between first and second ends and connectable to a casing perforating device, a first seal engaging cone secured around the elongate body, a second moveable seal engaging cone slidably locatable around the elongate body and a seal element between the first and second cones.

[0011] The second cone may include a pair of opposed retractable shoes adapted to selectively cover a rear actuating surface of the second cone. The retractable shoes may be retained in an extended positon by a frangible ember.

[0012] The apparatus may include a bypass passage therethrough. The bypass may include a check valve adapted to prevent flow therethrough in a downward direction.

[0013] According to a further embodiment, there is disclosed a method for perforating well casing comprising pumping a body down a wellbore, wherein the body is physically unconnected to the surface, determining a location of the body along the wellbore of the body and activating through a controller at least one casing perforating charge at a predetermined discharge location along the wellbore.

[0014] Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In drawings which illustrate embodiments of the invention wherein similar characters of reference denote corresponding parts in each view,

[0016] FIG. 1 is a cross-sectional view of a wellbore having a casing and a casing perforating apparatus therein.

[0017] FIG. 2 is a perspective view of an apparatus for perforating a casing according to a first embodiment of the present disclosure.

[0018] FIG. 3 is a cross-sectional view of the casing perforating apparatus of FIG. 2.

[0019] FIG. 4 is a cross-sectional view of the isolating section of the apparatus of FIG. 2 at an initial position.

[0020] FIG. 5 is a cross-sectional view of a setting tool of the isolating section of FIG. 4 at an activated position.

[0021] FIG. 6 is a perspective view of an apparatus for perforating a casing according to a further embodiment of the present disclosure.

[0022] FIG. 7 is a cross-sectional view of apparatus of FIG. 6.

[0023] FIG. 8 is an isolated cross sectional view of one perforating segment of the apparatus of FIG. 6 at an initial position.

[0024] FIG. 9 is a cross sectional view of the perforating segments of the apparatus of FIG. 6 at an activated or extended position spaced out along the wellbore.DETAILED DESCRIPTION

[0025] Referring to FIG. 1, a wellbore 10 is drilled into the ground 8 to a production zone 6 by known methods. The production zone 6 may contain a horizontally extending hydrocarbon bearing rock formation or may span a plurality of hydrocarbon bearing rock formations such that the wellbore 10 has a path designed to cross or intersect each formation. As illustrated in FIG. 1, the wellbore includes a vertical section 12 having a valve assembly or Christmas tree 14 at a top end thereof and a bottom or production section 16 which may be horizontal or angularly oriented relative to the horizontal located within the production zone 6. The casing 20 is formed of a plurality of casing 22 sections connected at collars 24 as are commonly known. After the wellbore 10 is drilled and casing 20 located therein according to known methods, the wellbore may be stimulated during a fracing operation as the operation is commonly referred to by pumping down a stimulation apparatus 30 as is further set out and described below. The stimulation apparatus 30 is physically unconnected to the surface through a tool string or wireline as are commonly known and is completely translated down the casing by pumping fluids through the casing in an operation commonly known as pump down. The apparatus 30 that is adapted to perforate the wellbore at a one or more predetermined locations or depths therealong.

[0026] Turning now to FIG. 2, the apparatus 30 comprises an elongate body extending between first and second ends, 32 and 34, respectively. The apparatus includes at least one casing perforating shot 36 located therein and a controller 40 adapted to control the discharge of the casing perforating shots 36. The casing perforating shots 36 may be of any known type and may be permanently or removably located in the apparatus. In particular, the casing perforating shots may comprise cartridges threadably or otherwise located within bores in the exterior of the apparatus. The elongate body may be further divided into a control section 40 and one or more shot segments 60. With reference to FIGS. 2 through 5, the apparatus may include a single shot segment wherein as illustrated in FIGS. 6 through 9, a plurality of shot segments may be utilized.

[0027] The controller 40 may include a battery and be formed of any known control circuitry, processor or the like and including all required accessories, including memory, data storage, batteries and signal transmitter / receivers. The controller may include an associated sensor 42 for determining the location of the apparatus within the well. The sensor 42 may be selected to sense a relative position of the apparatus within the well by counting casing collars (as are well known) or by determining the depth of the apparatus 30 within the wellbore. In particular the sensor 42 may be selected to count collars as a casing collar locator. The casing collar locator may be selected to detect casing thickness and identify thicker portion corresponding to a casing collar. Alternatively, the casing collar locator may identify cracks or metal separation identifying the connection between casing sections, including without limitation, a hall effect, ultrasound or magnetic flux sensors. It will be appreciated that any other casing collar locator methods may be utilized as well including, without limitation, a mechanical measurement of distance including a surveyors wheel, optical sensors measuring scattered return of light from the crack or seam or any combination of methods and devices.

[0028] In some embodiments, the sensor 42 may be selected to provide information to the controller 40 as to identify the depth of the apparatus 30 down the well. In particular, the sensor may comprise an ultrasound or sonar sensor configured to measure the distance of the apparatus 30 to an obstruction below the apparatus including, without limitation, the bottom of the well, a plug or isolation device downhole of the apparatus, including, a formerly located apparatus 30. Furthermore, a depth reader at the surface or other location adapted to read the depth of the apparatus 30 and send on or more signals, including without limitation, sonar, ultrasound, pressure pulse or other fluid communication signal or vibration or electric signal through the casing to the apparatus 30 to deploy perforating segments or engage the isolation section 70 as will be more fully described below. The controller 40 may also measure the speed of the apparatus 30 within the casing and time to further determine the proper location to discharge the shots 36. In such embodiments, an induction or magnetic flux device may be utilized in conjunction with a reader device to measure decay in the induction or magnetic flux so as to determine the apparatus speed.

[0029] In operation, the apparatus 30 is located in a casing 22 and disconnected from surface by a tool string, wireline or any other physical connection. Thereafter the apparatus 30 is pumped along with a fluid down the casing 22 and operates automatously under the control of the controller 40. The controller 40 in response to determining that the apparatus 30 is at the correct location down the well causes at least one of the shots 36 to discharge perforating the wellbore. Optionally, at a further location down the wellbore, the controller 40 may actuate an isolation device 70 as will be further described below to isolate the casing below the location of the casing perforations formed by the shot. Thereafter, increased fluid may be pumped down the casing to stimulate the well. As illustrated, the controller 40 and sensor may be located within the isolation section 70.

[0030] Turning to FIGS. 4 and 5, the isolation device is illustrated. It will be appreciated that although one isolation device style is illustrated herein, any other isolation device may also be utilized as are known. In particular as illustrated in FIGS. 4 and 5, the isolation device includes a top cone 72 and a moveable bottom cone 74 with a seal element 76 therebetween. The seal element 76 may be of any expandable material as are know and may optionally include one or more grip enhancing inserts therein or other surface treatments to enhance gripping on the casing. The isolation device may include at least one bypass passage 92 extending therethrough with a captured ball 92 therein adapted to cover the passage so as to prevent the flow in a downward direction therethrough as illustrated in FIG. 5 or uncovered so as to permit fluid flow upward through eh apparatus as illustrated in FIG. 4.

[0031] The apparatus 30 may be formed of any suitable material, including, without limitation, metals, plastics composite materials or ceramics. Optionally one or more of the elements of the apparatus 30 may be formed of a material that is degradable or dissolvable so as to permit the apparatus to be removed from its set location within the casing without milling. In particular, one or more of the elements of the apparatus may be formed of a dissolvable metal, a dissolvable plastic or the like, including without limitation thermoplastics, magnesium alloys, aluminium alloys and composite materials that are dissolvable and / or millable.

[0032] Turning now to FIGS. 6 through 9, the apparatus 30 may be formed with a plurality of shot segments 60, each including at least one casing perforating shot 36. As illustrated, each shot segment 60 may include a wedge 62 or other casing engaging member adapted to be extended into engagement with the casing and a releasable connector 64 to the next shot segment. In response to a signal from the controller 40, a wedge 62 of the top most shot segment 60 to engage the wedge 62, release the connector 64 and discharge the shots at any combination of timing. It will be appreciated that by sequentially releasing the shot segments, a plurality of casing perforations at a plurality of locations along the wellbore may be achieved. After forming such perforations, the controller 40 may engage the isolation device 70 to isolate the wellbore above the isolation device permitting stimulating. Optionally, isolation may occur prior to perforating.

[0033] While specific embodiments have been described and illustrated, such embodiments should be considered illustrative only and not as limiting the disclosure as construed in accordance with the accompanying claims.

Examples

Embodiment Construction

[0025]Referring to FIG. 1, a wellbore 10 is drilled into the ground 8 to a production zone 6 by known methods. The production zone 6 may contain a horizontally extending hydrocarbon bearing rock formation or may span a plurality of hydrocarbon bearing rock formations such that the wellbore 10 has a path designed to cross or intersect each formation. As illustrated in FIG. 1, the wellbore includes a vertical section 12 having a valve assembly or Christmas tree 14 at a top end thereof and a bottom or production section 16 which may be horizontal or angularly oriented relative to the horizontal located within the production zone 6. The casing 20 is formed of a plurality of casing 22 sections connected at collars 24 as are commonly known. After the wellbore 10 is drilled and casing 20 located therein according to known methods, the wellbore may be stimulated during a fracing operation as the operation is commonly referred to by pumping down a stimulation apparatus 30 as is further set o...

Claims

1. An apparatus for perforating a well casing comprising:an elongate body extending between first and second ends wherein the elongate body is physically unconnected to the surface;the elongate body including at least one casing perforating charge and a controller therein;wherein the controller is operable to activate at least one of the at least one casing perforating charge to perforate the casing at a predetermined location along the well.

2. The apparatus of claim 1 further including an isolating device for sealing below the discharge location.

3. The apparatus of claim 2 wherein the isolating device is included in the body.

4. The apparatus of claim 2 wherein the isolating device comprises an internal setting tool.

5. The apparatus of claim 4 wherein the setting tool is hydraulic.

6. The apparatus of claim 4 wherein the setting tool utilizes an explosive activating charge.

7. The apparatus of claim 4 wherein the setting tool utilizes hydrostatic pressure and an atmospheric chamber.

8. The apparatus of claim 1 wherein the body includes at least one degradable element so as to permit removal from the wellbore.

9. The apparatus of claim 8 wherein the at least one degradable element is dissolvable.

10. The apparatus of claim 9 wherein the at least one degradable element is selected from the group comprising dissolvable plastics and metals.

11. The apparatus of claim 8 wherein the at least one degradable element is selected to decompose after a predetermined period of time.

12. The apparatus of claim 1 wherein the controller is configured to detect and count casing collars passed by the body within the casing.

13. The apparatus of claim 12 wherein the controller includes a connected sensor adapted to sense the presence of a casing collar.

14. The apparatus of claim 13 wherein the sensor detects the thickness of the casing collar. The sensor may detect the crack between casing collar edges.

15. The apparatus of claim 13 wherein the controller is configured to detect the depth of the body within the wellbore.

16. The apparatus of claim 13 wherein the controller is configured to measure the depth form surface.

17. The apparatus of claim 13 wherein the controller is configured to measure the depth from a corresponding apparatus.

18. The apparatus of claim 15 wherein the controller measures depth utilizing sonar.

19. The apparatus of claim 15 wherein the controller receives a depth measurement from surface.

20. The apparatus of claim 15 wherein the controller measures depth to a next obstruction utilizing sonar.

21. The apparatus of claim 15 wherein the controller measures depth utilizing ultrasound.

22. The apparatus of claim 15 wherein the controller measures depth utilizing pressure pulses to surface.

23. The apparatus of claim 1 wherein the apparatus includes at least one shot segment, each containing the at least one casing perforating shot and a controller segment.

24. The apparatus of claim 23 wherein the apparatus includes a plurality of shot segments.

25. The apparatus of claim 24 wherein the each shot segment is selectably decouplable from a subsequent shot segment.

26. The apparatus of claim 25 wherein the each shot segment is decoupled in response to a signal from the controller.

27. An apparatus for stimulating a well comprising:an elongate body extending between first and second ends and connectable to a casing perforating device;a first seal engaging cone secured around the elongate body;a second moveable seal engaging cone slidably locatable around the elongate body; anda seal element between the first and second cones.

28. The apparatus of claim 27 wherein the second cone includes a pair of opposed retractable shoes adapted to selectively cover a rear actuating surface of the second cone.

29. The apparatus of claim 28 wherein the retractable shoes is retained in an extended positon by a frangible ember.

30. The apparatus of claim 27 wherein the apparatus includes a bypass passage therethrough.

31. The apparatus of claim 30 wherein the bypass includes a check valve adapted to prevent flow therethrough in a downward direction.

32. A method for perforating well casing comprising:pumping a body down a wellbore, wherein the body is physically unconnected to the surface;determining a location of the body along the wellbore of the body; andactivating through a controller at least one casing perforating charge at a predetermined discharge location along the wellbore.

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