Pre-verification of perforation alignment

A perforating system, comprising a perforating gun with shaped charges, and a pre-detonation orientation apparatus and method. The pre-detonation orientation device comprises an orientation device in communication with the firing means of the perforating gun. Detonation of the shaped charges can be contingent upon the perforating gun orientation.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The disclosure herein relates generally to the field of oil and gas production. More specifically, the present disclosure relates to a method and apparatus for aligning perforating charges. Yet more specifically, the present disclosure concerns a method and apparatus for confirming that a perforating charge is aligned in a certain direction prior to detonating the perforating charge.

2. Description of Related Art

Perforating systems are used for the purpose, among others, of making hydraulic communication passages, called perforations, in wellbores drilled through earth formations so that predetermined zones of the earth formations can be hydraulically connected to the wellbore. Perforations are needed because wellbores are typically completed by coaxially inserting a pipe or casing into the wellbore, and the casing is retained in the wellbore by pumping cement into the annular space between the wellbore and the casing. The cemented casing is provided in the wellbore for the specific purpose of hydraulically isolating from each other the various earth formations penetrated by the wellbore. As is known, hydrocarbon-bearing strata, such as reservoirs, exist within these formations. The wellbores typically intersect these reservoirs.

Perforating systems typically comprise one or more perforating guns strung together, these strings of guns can sometimes surpass a thousand feet of perforating length. Included with the perforating guns are shaped charges that typically include a charge case, a liner, and a quantity of high explosive inserted between the liner and the charge case. When the high explosive is detonated, the force of the detonation collapses the liner and ejects it from one end of the charge at very high velocity in a pattern called a “jet”. The jet penetrates the casing, the cement and a quantity of the formation thereby forming a perforation in the formation that enables fluid communication between the wellbore and its surrounding formation.

FIG. 1is a side partial cutaway view of a perforating system5comprising a perforating string7suspended within a wellbore25. The perforating string7comprises a series of perforating guns13axially connected to one another. Tubing9is shown attached to the perforating string7, the tubing9comprises a raising/lowering means and can also facilitate communication between the perforating string7and a surface truck11. Using tubing for a raising/lowering means enables system deployment within all forms of deviated wellbores as well as horizontal wells. Optionally, the raising/lowering means may comprise a wireline or slickline, a tractor may be employed for wireline use within deviated or horizontal wells. The surface truck11typically includes a winch type device for perforating string7disposal and retrieval. Also included within the surface truck11is an interface enabling surface personnel to transmit commands and receive data to and from the perforating string7. The communicated data between the surface and the string7is generally provided via the wireline9. The perforating string7ofFIG. 1is shown disposed in a deviated portion of the wellbore25. For the purposes of illustration, perforations21are shown that extend from the wellbore25into the surrounding formation19.

The shaped charges should be aimed in a particular direction for maximum penetration of a hydrocarbon producing zone, for avoiding hardware attached to the casing, sand control or to avoid shooting into zones having either water, gas, or both. Aiming of the shaped charges can be accomplished by aligning the perforating gun13in a particular orientation. One manner of accomplishing perforating gun orientation is to asymmetrically load a perforating gun so that the loading will cause the gun to rotate into the desired or designed orientation. With regard now toFIG. 2, one manner of loading is shown that comprises including a weight14in the gun, where the weight runs along a portion of its inner housing or attached to the shape charge tube carrier. In some instances however, in spite of the asymmetric loading the guns may stick within the casing and not freely rotate into the desired orientation. With reference now toFIG. 2again, the shaped charge27should be aligned with the line “L”, but instead points an angular distance θ away from line “L” to produce the perforation21.

BRIEF SUMMARY OF THE INVENTION

A perforating system comprising a perforating gun, an orientation indicator associated with the perforating gun, and a perforating gun actuator in active communication with the orientation indicator. The perforating gun actuator may be coupled to the perforating gun and may comprise a controller as well as a firing head. The controller may be configured to produce a perforating gun detonation signal in response to a signal from the orientation indicator. The signal may be an indication of a desired perforating gun orientation. A shaped charge may be included with the perforating system.

Optionally, the perforating system may comprise a perforating gun having a shaped charge, an orientation device associated with the perforating gun, and a controller in communication with the orientation device configured to provide a detonation signal to the perforating gun in response to a signal received from the orientation device, wherein the received signal is indicative of a desired orientation of the perforating gun.

Also disclosed herein is a method of perforating in a wellbore comprising, monitoring the orientation of a perforating gun, and activating the perforating gun based on the evaluated orientation. The method may include determining if the perforating gun is in a desired alignment. The method may also include activating the perforating gun upon confirmation that the perforating gun is in the desired alignment. Optionally, the perforating gun orientation may be adjusted during operation.

DETAILED DESCRIPTION OF THE INVENTION

Disclosed herein is a system and method for the perforating of a wellbore into an adjacent subterranean formation. The system and method include provisions for actively monitoring the real time orientation of a perforating gun prior to the detonation of its associated shaped charges. The method and apparatus described herein compares the real time orientation with a desired orientation. Shaped charge detonation is not initiated until the real time orientation matches the desired orientation. The system and method disclosed herein can be adjusted so that the “matching” is substantially exact or within an angular range.

With reference now toFIG. 3a perforating string29is shown in a side view. This embodiment of the perforating string29comprises a series of perforating guns31connected at their respective ends by connector subs33. However the scope of the present disclosure is not limited to the size and configuration of the perforating string29illustrated, but can include a single perforating gun, or a string comprised of a plurality of guns that far exceeds the guns in the illustrated string29. An orientation device39(also referred to herein in the alternative as an orientation indicator) is shown provided with the perforating string29. By having the orientation device39“with” the perforating string29means it can be housed within a perforating gun31, within a connector sub33, outside of a perforating gun31or sub33, or in axial connection with the sub33or gun31. In this embodiment the orientation device is shown disposed within the connector subs33. However each perforating gun31or predetermined sections of a gun string should be in association with an orientation device39. By “association” it is meant that the orientation device39monitors its associated perforating gun orientation. The azimuthal placement of a perforating gun within a wellbore is one example of what is meant by the term “orientation.”

Also included with the perforating string29is a controller sub35disposed at one end of the perforating string29. A controller37is shown in dashed outline included within the controller sub35. As seen in the embodiment ofFIG. 3the controller37is in communication with each of the orientation devices39of this embodiment. The communication can be through individual, or combinations of, telemetry channels used for signaling. Examples are hard wire, fiber-optic, mud pressure pulse, electromagnetic field, and acoustic stress waves in steel, and any other form of communication that might transmit data from the orientation device that can be received by the controller37. Optionally, the communication may comprise an ultra low frequency signal including combination of ultra-low frequency signals. Communications may further include ranges in frequencies (“chirps”) in which the frequency is continuously varied between an initial and final frequency. Any generally known method of modulating the signal such as changing its phase (phase-shift-keying), its frequency (frequency-shift-keying), or its amplitude (amplitude-shift-keying), or combinations of these techniques, may be used to place information on the signal that is transmitted between orienting device and controller37.

In one embodiment having more than one controller sub35, each controller sub35includes a transmitter emits a signal at a select frequency when properly aligned. The signal could be a discrete frequency modulated in amplitude that identifies each individual controller sub. Misaligned subs will therefore not emit an identifying signal in the selective particular frequency. Thus if no signal is received for a particular frequency, it can be determined that the corresponding controller sub35(and thus the associated shaped charges) are not in the desired orientation. This knowledge provides some options of corrective action over simply knowing that one of potentially many controller subs35are not properly aligned.

In one example of operation of the system ofFIG. 3, the perforating string29is inserted within a well bore and lowered to the desired depth for perforating. Once reaching the desired depth the controller37queries each of the orientation devices in order to obtain information regarding the orientation of each of the perforating guns31. It should be pointed out that prior to inserting the perforating gun within the wellbore, the desired or designed orientation for each perforating gun would likely have been determined. It is well within the capabilities of those skilled in the art to determine the proper orientation of the perforating gun and configure the perforating gun so that it is able to be disposed in the proper orientation. One example of orienting a perforating gun, as discussed above, involves weighting the perforating gun in an asymmetric fashion to attain a desired or designed orientation of the perforating gun within the well bore. Once receiving the orientation data from each of the orientation devices39, the controller37performs an evaluation step to ascertain if the perforating gun31is aligned or oriented as desired. A desired orientation of a perforating gun results in perforations that will are pointed or aimed in the desired direction. The desired orientation may include a specific azimuthal angle, either with or without some tolerances, or can include an angular, or radial orientation, range of values. Examples of angular ranges include up to 270°, up to 180°, up to 90°, up to 45°, up to 30°, and up to 15°.

The orientation evaluation may be performed for a single perforating gun, or for each perforating gun making up a perforating gun string. The controller may be configured to recognize when each perforating gun is in a desired orientation, and send a corresponding detonation signal upon recognition that one or all of the perforating guns of a perforating string are in a desired orientation. Once the controller37determines that each perforating gun is in its desired or designed alignment, the controller transmits a detonation signal that will in turn detonate shape charges associated with the now properly oriented perforating guns. The controller or other device for initiating perforation of the perforating string can be at surface as well as connected with a perforating string or individual perforating gun. Accordingly both the steps of activating the perforating gun by a controller as well as monitoring the orientation of the perforating gun can be performed with a controller that is disposed downhole with the perforating system or at the surface with system operator personnel.

Optionally, should the controller37determine that one or more of the perforating guns is not in proper or desired alignment, corrective action may be taken. The signal can be sent by the associated wireline85to the surface where surface operators can take corrective action. Corrective action may comprise “cycling” the perforating string within the well bore by raising and lowering the perforating string to effect the settling of the individual perforating guns into their proper alignment. After the step of cycling perforating gun orientation can again be evaluated by the controller37obtaining orientation data from each of the orientation devices and then re-evaluating if the guns are in their desired alignment. As discussed above, once all guns are determined to be in a proper alignment, the step of perforating can then be commenced. Should further cycling be required to adjust the guns into a desired alignment, that step can be repeated as well. Moreover, corrective action may include selectively choosing to not fire certain guns or gun segments based on if the segments are misaligned.

The orientation indicator or orientation device is associated with each of the perforating guns. That is the indicator is coupled with the perforating gun so that the indicator rotates along with any rotation of the perforating gun. Thus within the perforating gun the orientation indicator or device will necessarily rotate as it is connected to the perforating gun. However in the case when the indicator is within an associated sub, the sub must be connected to the gun such that it rotates when the gun rotates.

The controller37may be configured with embedded code therein that recognizes and decodes each signal received from the one or more orientation devices for determining if the perforating gun or guns in the desired orientation. Based upon the signal of proper orientation a signal is produced by the controller that in turn effectuates perforating gun detonation in response to these positive signals from the one or more orientation indicators. With regard to communication between the orientation device or orientation indicator and the controller37, in one embodiment of the system described herein the communication is active. Active communication between these two devices comprises a real time and continuous communication between these two elements from the period of time leaving up to the perforation step. Active communication also includes conveying information (such as information pertaining to orientation) in discreet time increments as well as continuous. Thus active communication can provide information over multiple time increments and is not restricted to orientation information for a specific point in time. The controller may comprise an information handling system (IHS). The IHS may include a processor, memory accessible by the processor, nonvolatile storage area accessible by the processor, and logics for performing each of the steps above described.

FIGS. 4a-4dprovide examples of different embodiments of the orientation device39. With regard now toFIG. 4a, the orientation device39acomprises an inner wall41circumscribed by an outer wall43thereby forming an annulus47between these two walls. A revolving element45is disposed within that annulus and allowed to freely rotate or revolve in an orbital fashion through this annulus. Due to gravitational forces, when used in conjunction with a perforating gun, the revolving element should make its way to the lower most portion of the annulus47. Included within opposing faces of the inner and outer wall (41,43) is a pair of opposing conductive surfaces (49,51). The opposing surfaces are structured such that when the revolving element45is disposed between these two surfaces, an associated electrical circuit (not shown) closes thereby allowing current to flow from one conductive surface to the other. Accordingly, the orientation device39aofFIG. 4acould be disposed within a perforating gun such that its desired orientation or alignment within a well bore would coincide when the revolving element45is residing between these conductive surfaces (49,51).

The revolving element45could be any member capable of rolling through the annulus47in response to azimuthal rotation of the orientation device39a. Additionally, the revolving element45should also be conductive and shaped so it can close the electrical circuit when it is between the opposing conductive surfaces (49,51). Examples of the revolving element45include a cylindrically shaped member, a spherical member, an oval shaped member, and disks axially connected. Moreover, the opposing conductive surfaces (49,51) may comprise a raised portion as shown inFIG. 4a, but may also include extending conductive members, such as flexible contacts extending from the walls (41,43).

FIG. 4bprovides another embodiment of an orientation device39b. In this embodiment, a liquid interface module53is shown situated within an annular housing. The liquid interface module53comprises immiscible liquids, for example such as oil and water where one is polar and one is non-polar. In the embodiment shown, the first and second liquids (55,57) have different polarities and thus do not mix. Additionally as shown, the first liquid55has a density lower than that of the second liquid57. The surface along which these liquids (55,57) contact forms an interface58. Disposed on the edge of the liquid interface module is an interface detector59. The liquid interface detector is able to detect that interface58between the first and the second liquid (55,57). As with the revolving element embodiment, the liquid interface module53can be calibrated, such that when the perforating gun is in the desired orientation the liquid interface58will be aligned with the interface detector59on one or both sides of the liquid interface module53. When the interface58is aligned with the interface detector59a signal may be transmitted representing proper orientation of the associated perforating gun.

FIG. 4cprovides another embodiment of an orientation device39c. In this embodiment a switch61is shown comprising a housing63. Within a portion of the housing a conductive material65is shown residing therein. The conductive material can be a liquid metal, or can be a particulated metal that flows within the housing based upon a gravitational pull. As shown, the conductive material65is in contact with lead67disposed on both sides of the switch61. Therefore the switch can be designed such that when it is in a particular orientation the leads on one or both sides of the housing63can be in electrical communication with one another. The electrical communication can be an indication of the orientation of an associated perforating gun.

In the embodiment ofFIG. 4d, the orientation device39dcomprises a switch assembly69, wherein the switch assembly69comprises a pendulum element71and a contact73. The pendulum element is hingely affixed within an annular housing on one end of the housing and can rotate into contact with the contact73. The contact may optionally be provided with a flexible tip75that allows passage past the contact of the pendulum element71. As with the other devices this device can be arranged with an associated perforating gun such that the pendulum element71is in connective and electrically communicative contact with the contact73thereby allowing for electrical communication between these two elements when this device is an orientation indicative or representative of a desired orientation of an associated perforating gun. Each orientation device (39a-39d) may be disposed within a perforating gun, or some other device such as a connector sub associated with the perforating gun.

Accordingly use of any of these devices with the aforementioned method can result in a situation where a perforating gun can be disposed in a well bore and orientation of the well bore can be verified prior to activation of the perforating gun. For example, with reference now toFIG. 5, a cross-sectional area of a portion of a perforating gun is shown, wherein the perforating gun comprises shaped charges79pointing in directions radially away from the perforating gun77. To produce proper alignment of the shaped charges79, a weight81is shown disposed along the inner housing of a portion of the perforating gun77(that positions the perforating gun77in the designed or desired orientation). As shown the weight aligns the shape charges79with a desired or designed orientation represented by dashed lines L.

The perforating string may include a firing head that is in active communication with the controller37. As is known the firing head is responsible or used in initiating detonation through primer cord connected to each of the shape charge of the perforating gun. The firing head can actuate strictly electrical, strictly mechanical, or a combination of both with some redundant and isolated features.

InFIG. 6one alternative embodiment of the perforating string29ais shown in a partial side cutaway view. In this embodiment the string29ais conveyed within the wellbore25via tubing88. A wireline90is shown coaxially inserted within tubing88with a receiver92on its terminal end. The receiver92can be disposed within the tubing once the pertbrating string29ahas been deployed within the wellbore25. In this embodiment, the receiver92detects signals emitted by transmitters (not shown) regarding perforating gun orientation. For example, a signal may be transmitted from the orientation device39ainside sub33aand indicating orientation of the perforating gun31a. Optionally the receiver92can be deployed in the tubing88and inserted into the wellbore along with the remaining portions of the system. This embodiment provides for the flexibility of removing the receiver just previous to detonation of the perforation string thereby reducing damage to the receiver92.

FIG. 7shows yet another alternative embodiment of the device described herein. In this embodiment the receiver92is shown releaseably attached to the uppermost portion of the perforating string29a. A frangible connection (not shown) temporarily couples the receiver92to the perforating string. When desired the receiver92may be separated from the perforating string29aand removed from the wellbore25by reeling in the wireline90.

The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. For example, the invention described herein is applicable to any shaped charge phasing as well as any density of shaped charge. The power used for operating the downhole components listed herein can be supplied by onboard batteries, or via the conveyance means. Moreover, the invention can be utilized with any size of perforating gun. It also should be pointed out that the apparatus herein disclosed is not limited to a shaped charge for use with a perforating gun, but can also include any type of ballistics shaped charge—such as those shaped charges used in weaponry and ordinance related technology as well as pressurized fluid used in perforating. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.