Method and apparatus for actuating a downhole device

Abstract: An apparatus (100) for actuating a hydraulically controllable device disposed in a wellbore. The apparatus (100) comprises a downhole hydraulic fluid source (134), a hydraulic fluid passageway (136) providing a communication path between the downhole hydraulic fluid source (134) and the hydraulically controllable device, a valve (144) disposed within the hydraulic fluid passageway (136) and a downhole electronics package (138). The downhole electronics package (138) receives a signal from the surface to operate the valve (144) from the closed position to the open position such that hydraulic pressure from the downhole hydraulic fluid source (134) actuates the hydraulically controllable device.

Description: This invention relates general to the field of actuating hydraulically controllable downhole tools and, in particular to, a remotely operated service tool having a self-contained hydraulic system for actuating hydraulically controllable downhole tools disposed within a wellbore. The invention relates to a method and apparatus for actuating a downhole device, and more particularly relates to a method and apparatus for hydraulically actuating a downhole device from a remote location The background to the invention will be described, by way of example, in connection with setting a packer assembly in a wellbore that traverses a hydrocarbon formation Heretofore in this field, during the treatment and preparation of the wellbore for production, a packer assembly and sand control screen along with a service tool are run into the wellbore on a work string. The setting of the packer assembly against the casing is typically accomplished by manipulating the service tool. The success of such operations is dependent upon the ability to reciprocate the service tool vertically or to rotate it relative to the packer assembly. It has been found, however, that rotational displacement of the service tool in deviated wells is difficult to perform reliably because of frictional binding between the work string and the casing. Accordingly, vertical reciprocal movements have been preferred for setting and releasing packer assemblies in such instances. During run-in, the packer assembly is mechanically locked in the unset condition by shear pins and anti-preset lugs that support the weight of the packer assembly along with the hang weight of other components such as a swivel shear sub, blank pipe, a sand control screen, a polished nipple, a tail screen, and a packer assembly. The shear pins and anti-preset lugs can safely support the combined weight of the downhole equipment. The shear pins are rated to yield to a preset shearing force to separate and release the service tool after the packer assembly has been set. It has been found, however, that in deviated or otherwise obstructed wellbores, shear pins designed to shear in response to vertical reciprocation may be damaged and the packer assembly may sometimes be inadvertently preset in response to frictional loading between the packer assembly and the wellbore in tight spots. It has also been found that when operating in slanted or deviated wellbores, it is sometimes difficult to transmit sufficient force downhole from the surface to set mechanically actuated packer assemblies. The frictional engagement between the wellbore and the work string interferes with the transmission of the necessary mechanical force to set the packer assembly. To overcome these difficulties, pressure may be applied to the fluid column within the work string to transmit the required packer assembly setting force. For example, the packer assembly may be set by dropping a ball through the work string into the service tool. Pressurized fluid is then pumped down the work string to shear the shear pins, thereby setting the packer assembly. During gravel packing or frac packing operations, it is desirable to remove the ball from the service tool. It has been found, however, that in slanted or deviated wellbores or in tapered work strings it is difficult to reverse the ball out of the work string. In addition, it has been found that the ball, in certain installation, may damage downhole equipment when it is run-in the service tools. WO 98/55731 describes an electro-hydraulic well tool actuator. EP 099342 describes a remotely controllable well control system. Therefore a need has arisen for an improved service tool for running and setting a packer assembly in a wellbore. A need has also arisen for an improved service tool for setting a packer assembly without the need for translational or rotational movement of the service tool with respect to the packer assembly and without the need for running a ball into the service tool. A need has further arisen for such a service tool that can set a packer assembly in a deviated or slanted wellbore. The present invention disclosed herein comprises a service tool for hydraulically actuating a downhole device from a remote location. The service tool utilizes hydraulic pressure for actuating the downhole device without the need for translational or rotational movement of the service tool and without the need for running a ball into the service tool. The service tool of the present invention may be used in any wellbore including a deviated or slanted wellbore. The service tool of the present invention comprises a downhole hydraulic fluid source, a hydraulic fluid passageway that provides a communication path between the downhole hydraulic fluid source and the hydraulically controllable device, a valve disposed within the hydraulic fluid passageway and a downhole electronics package. The downhole electronics package receives a signal from a surface installation to operate the valve from the closed position to the open position, thereby transmitting hydraulic pressure from the downhole hydraulic fluid source to the hydraulically controllable device and actuating the hydraulically controllable device. The hydraulic fluid source may include a housing and a sleeve that define a hydraulic fluid chamber therebetween having hydraulic fluid contained therein. The sleeve may be slidably disposed about the housing and has first and second positions relative to the housing. The sleeve may be operated from the first position to the second position, responsive to hydrostatic pressure, once the valve is operated from the closed position to the open position. The sleeve and the housing may also define an atmospheric air chamber therebetween having air contained therein. The downhole electronics package may include a transducer that receives the signal from a surface installation. The transducer may be selected from a variety of transducers that are suitable for downhole reception of a signal including, but not limited to, an acoustic transducer, a pressure reception of a signal including, but not limited to, an acoustic transducer, a pressure pulse transducer, an electromagnetic transducer and the like. The transducer may receive the signal and relays the signal to the controller of the valve. The downhole electronics package may also include a battery pack to provide a source of electrical power. In a first aspect of the present invention, there is provided a method for actuating a downhole device comprising the steps of: sending a signal to a downhole electronics package; establishing a communication path between a self-contained downhole hydraulic fluid source and the downhole device in response to the signal; transmitting a hydraulic fluid from the self-contained downhole hydraulic fluid source to the downhole device through the communication path by utilising hydrostatic pressure from an annulus surrounding the downhole device to urge the hydraulic fluid from the self-contained downhole hydraulic fluid source to the downhole device; and actuating the downhole device in response to the hydraulic fluid. The method may also include operating a valve to establish a communication path between the downhole hydraulic source and the downhole device and utilizing hydrostatic pressure to transmit the hydraulic fluid from the downhole hydraulic source to the downhole device. In the method of the present invention, the signal may be sent to a downhole electronics package from a surface installation. The signal may be an acoustic signal, a pressure pulse signal, an electromagnetic signal or other suitable signal the may be received downhole. The actuation of the downhole device may further include the setting a downhole device such as a packer assembly, or the manipulating a downhole device such as a slidingly sleeve, a fluid control device or a well control device. Additionally, the actuation of the downhole device may be achieved by axially shifting a component of the downhole device or rotatably operating a component of the downhole device. In an embodiment, the step of transmitting hydraulic pressure further comprises the step of operating a valve from the closed position to an open position. In an embodiment, the step of sending a signal to a downhole electronics package further comprises sending a signal from a surface installation. In an embodiment, the step of sending a signal to a downhole electronics package further comprises sending an acoustic signal, a pressure pulse signal or an electromagnetic signal. In an embodiment, the step of transmitting hydraulic pressure from a downhole hydraulic source to the downhole device further comprises utilizing hydrostatic pressure to transmit the hydraulic pressure from the downhole hydraulic source to the downhole device. In an embodiment, the step of actuating the downhole device further comprises setting a downhoole device. The downhole device in this embodiment in preferably a packer assembly. In an embodiment, the step of actuating the downhole device further comprises manipulating a downhole device. In an embodiment, the step of actuating the downhole device further comprises axially shifting a component of the downhole device. In an embodiment, the step of actuating the downhole device further comprises rotatably operating a component of the downhole device. In one embodiment, the method further comprises the step of simultaneous with said transmitting step, compressing air in an air chamber to dampen the response to the hydrostatic pressure. In an embodiment, the step of sending a signal from a surface installation to a downhole electronics package further comprises sending an acoustic signal, a pressure pulse signal or an electromagnetic signal. In an embodiment, the step of establishing a communication path between a downhole hydraulic source and the downhole device further comprises operating a valve from a closed position to an open position. In an embodiment, the step of transmitting hydraulic pressure from a downhole hydraulic source to the downhole device further comprises utilizing hydrostatic pressure to transmit the hydraulic pressure from the downhole hydraulic source to the downhole device. In an embodiment, the step of actuating the downhole device further comprises setting a downhole device. The downhole device in this embodiment is preferably a packer assembly. In an embodiment, the step of actuating the downhole device further comprises axially shifting a component of the downhole device. In an embodiment, the step of actuating the downhole device further comprises rotatably operating a component of the downhole device. According to another aspect of the invention there is provided an apparatus for actuating a hydraulically controllable device disposed in a wellbore comprising: a self-contained downhole hydraulic fluid source storing hydraulic fluid proximate the hydraulically controllable device; a hydraulic fluid passageway providing a communication path between the self-contained downhole hydraulic fluid source and the hydraulically controllable device; a valve disposed within the hydraulic fluid passageway; and a downhole electronics package receiving a signal from the surface to operate the valve from a closed position to an open position, thereby transmitting hydraulic pressure from the downhole hydraulic fluid source to the hydraulically controllable device by utilising hydrostatic pressure from an annulus surrounding the hydraulically controllable device to urge the hydraulic fluid from the self-contained downhole hydraulic fluid source to the hydraulically controllable device, thereby actuating the hydraulically controllable device. In an embodiment, the hydraulic fluid source further comprises a housing and a sleeve slidably disposed about the housing, the sleeve and the housing defining a hydraulic fluid chamber therebetween having hydraulic fluid contained therein, the sleeve operating from a first position to a second position relative to the housing in response to hydrostatic pressure once the valve is operated from the closed position to the open position. In an embodiment, the sleeve and the housing further define an air chamber therebetween having air contained therein. In an embodiment, the downhole electronics package further comprises an acoustic transducer, a pressure pulse transducer or an electromagnetic transducer. In an embodiment, the downhole electronics package further comprises a battery pack. In an embodiment, the hydraulically controllable device is a packer assembly. In an embodiment the operation of the valve from the closed position to the open position allows the sleeve to operate from a first position to a second position relative to the housing in response to hydrostatic pressure in the annulus such that the air in the air chamber is compressed to dampen the movement of the sleeve from the first position to the second position, and simultaneously the hydraulic fluid in the self-contained hydraulic fluid source is urged from the self-contained downhole hydraulic fluid source to the hydraulically controllable device, thereby actuating the hydraulically controllable device. In an embodiment, the downhole electronics package further comprises In an embodiment, the downhole electronics package further comprises an acoustic transducer, a pressure pulse transducer, or an electromagnetic transducer. In an embodiment, the downhole electronics package further comprises a battery pack. In an embodiment, the hydraulically controllable device is a packer assembly. Reference is now made to the accompanying drawings, in which: Figure 1 is a schematic illustration of an offshore oil and gas platform operating an embodiment of a service tool according to the present invention; Figures 2A-2F are quarter-section views of an embodiment of a service tool according to of the present invention in the run-in position that is attached to a packer assembly in the unset position; and Figures 3A-3F are quarter-section views of an embodiment of a service tool according to the present invention after operation of the service tool and actuation of a packer assembly to the set position. Referring to figure 1, a service tool operably coupled to a packer assembly in use with an offshore oil and gas platform is schematically illustrated and generally designated 10. A semi-submersible platform 12 is centered over a submerged oil and gas formation 14 located below sea floor 16. A well 18 extends through the sea 20 penetrating sea floor 16 to form wellbore 22 which traverses various earth strata. Platform 12 has hoisting apparatus 24 and a derrick 26 for raising and lowering pipe strings such as work string 28. Attached to the lower end of work string 28 is service tool 30 that is landed within the bore of packer assembly 32. As will be explained in greater detail below, packer assembly 32 has mechanically actuated slips which set expandable annular seal elements 34 against the inside bore of tubular well casing 36. Packer assembly 32 is actuated by hydraulic fluid from service tool 30. Service tool 30 is remotely operated by a signal generated at surface installation 38. After setting packer assembly 32, service tool 30 remains sealed against the inner bore of packer assembly 32 to, for example, allow a gravel laden slurry to be pumped through the work string 28 and the service tool 30 into annulus 40 between the casing 36 and a sand control screen 42. A seal is provided above and below formation 14 by expanded annular seal elements 34 carried on packer assembly 32 and expanded annular seal elements 44 carried on packer assembly 46. During the gravel pack operation, the annulus 40 is filled with slurry, and the slurry is pumped through perforations 48 formed in the sidewall of the well casing 36 into the surrounding formation 14. Even though Figure 1 depicts a cased vertical well, it should be noted by one skilled in the art that the service tool of the present invention is equally well-suited for operation in uncased wells, deviated wells, inclined wells or horizontal wells. Referring now to figures 2A - 2F, the service tool 100 of the present invention is rigidly locked onto packer assembly 102 during the initial run-in operation. According to this arrangement, the service tool 100, packer assembly 102 and all the equipment which is hung off of packer assembly 102 are run-in through the bore of casing 36 as an assembled unit. As best seen in figure 2E, a group of separation shear pins 104 having appropriate shear strength for supporting the packer assembly hang weight connect the packer assembly mandrel 106 to the service tool mandrel 108. The shear pins 104 are rated to safely support the combined weight of the downhole equipment, and are rated to yield to a preset shearing force to separate and release the service tool 100 from the packer assembly 102 after setting packer assembly 102. Referring specifically to figure 2A, service tool 100 includes a hydraulic power unit 110. Hydraulic power unit 110 has an inner mandrel 112. Disposed about inner mandrel 112 is an air chamber piston 114 and an air chamber sleeve 116. Disposed between air chamber sleeve 116 and inner mandrel 112 is air chamber 118. Also disposed about inner mandrel 112 is a retainer member 120. Between retainer member 120 and air chamber piston 114 is an annular housing extension 122 having a port 124 therein. Air chamber sleeve 116 includes a port 125. Disposed about inner mandrel 112 is a retainer member 126. Atmospheric air may be contained within air chamber 118. Below air chamber 118 and disposed about inner mandrel 112 is a hydraulic piston 128, a hydraulic sleeve 130 and a retainer member 132. Disposed between hydraulic sleeve 130 and inner mandrel 112 is a hydraulic fluid chamber 134 that contains hydraulic fluid. Disposed between retainer member 132 and inner mandrel 112 is a hydraulic fluid passageway 136. Referring now to figure 2B, a control assembly 138 is disposed about inner mandrel 112. Control assembly 138 includes a battery pack 140 that provides electrical power to a transducer 142. Transducer 142 receives signals from surface installation 38 of figure 1 in the form of acoustic signals, electromagnetic signals, pressure pulse signals or other suitable signals that may transmit information from a remote location to transducer 142, such methods being well- known to those skilled in the art. Disposed within hydraulic fluid passageway 136 is a valve 144 that may be operated responsive to signals received by transducer 142. Referring now to figures 2C - 2D, at the lower end of inner mandrel 112 is a connector member 146 that is threadably attached to a connector member 148. Threadably and sealably connected to connector member 148 is outer housing 150. Outer housing 150 includes the lower end of hydraulic fluid passageway 136. The upper portion of service tool mandrel 108 extends into outer housing 150. Outer housing 150 includes an outer housing extension 152. Disposed between outer housing extension 152 and service tool mandrel 108 is operating piston 154 which includes an operating piston extension 156. The relative movement of operating piston extension 156 and service tool mandrel 108 is prevented by shear pins 184 as best seen in figure 2E. Below operating piston extension 156 is a transfer support assembly 158 that includes a group of anti-preset lugs 160 carried by a collet 162. Anti-preset lugs 160 are engaged against the lower shoulder of annular flange 164 which is formed on a tube guide extension 166. Setting sleeve extension 166 is aligned to receive sleeve 168. The hang weight of packer assembly 102 is transmitted through a setting sleeve 170 through the anti-preset lugs 160 and collet 162 to service tool mandrel 108. As such, packer assembly 102 and the equipment attached thereto are supported by the work string 28 through service tool mandrel 108, anti-preset lugs 160 and setting sleeve 170. This configuration results in a decoupling of handling forces which arise during the run-in procedure with respect to shear pins 104. The service tool 100 is provided with a locking flange 172 which is engaged by a shoulder portion 174 of the collet 160. Collet 160 is held in its position shown in figure 2E by its finger portions 176 having their head portions 178 received in a detent groove 180 formed in the service tool mandrel 108 above the upper shoulder of the locking flange 172. The head portion 178 is engaged and prevented from deflecting by a piston shoulder 182 which forms a part of operating piston extension 156. As best seen in figures 2E - 2F, connected to the lower end of setting sleeve 170 is connector sub 186. Disposed between connector sub 186 and packer assembly mandrel 106 is a slip ring assembly 188 that is used to retain the seal element 190 and casing slips 192 of packer assembly 102 in the set position. It should be apparent to those skilled in the art that the use of directional terms such as above, below, upper, lower, upward, downward, etc. are used in relation to the illustrative embodiments as they are depicted in the figures, the upward direction being towards the top of the corresponding figure and the downward direction being toward the bottom of the corresponding figure. It is to be understood that the downhole components described herein, for example, service tool 100, may be operated in vertical, horizontal, inverted or inclined orientations without deviating from the principles of the present invention. The operation of service tool 100 and packer assembly 102 will now be described with reference to figures 3A - 3F, wherein service tool 100 and packer assembly 102 are shown following their operation. Transducer 42 receives a signal from surface installation 38 to initiate the actuation of a hydraulically controllable device such as packer assembly 102. Transducer 142 converts the signal to an electrical signal that is used to open valve 144, as best seen in figure 3B. Once valve 144 is open, the hydrostatic pressure within annulus 40 downwardly biases air chamber piston 114, air chamber sleeve 116, hydraulic piston 128 and hydraulic sleeve 130, as best seen in figure 3A. The hydraulic fluid in hydraulic chamber 134 may now pass through hydraulic fluid passageway 136 and valve 144. As best seen in figure 3D, the hydraulic fluid downwardly biases operating piston 154 including operating piston extension 156 and accumulates in hydraulic fluid reservoir 194. Operating piston 154 is guided for movement along the external surface of the service tool mandrel 108 by outer housing extension 152. Once the hydraulic pressure is increased to a level great enough to cause shear pins 184 to shear, operating piston 154 is permitted to drive sleeve 168 downwardly against annular flange 164 of setting sleeve extension 166 as best seen in figure 3E. Collet 162 remains in place as operating piston 154 is driven downwardly until shoulder 182 clears head portions 178, thereby permitting it to deflect and also permitting transfer support assembly 158 to move downwardly along the locking flange 172. Thereafter, the spring loaded anti-preset lugs 160 retract radially inwardly. When this occurs, the hang weight of packer assembly 102 is transferred from anti-preset lugs 160 to shear pins 104. Setting sleeve 170 is movable relative to packer assembly mandrel 106. Setting sleeve 170 is moved downwardly relative to packer assembly mandrel 106 in response to continued extension of operating piston 154. As operating piston 154 nears the limit of its extension along service tool mandrel 108, slips 192 are engaged and set against the inside bore of the well casing 36 as best seen in figure 3F. Because the packer assembly mandrel 106 is anchored onto the service tool mandrel 108 by separation shear pins 104, setting sleeve 170 continues its downward movement relative to packer assembly mandrel 106. Once the desired slip setting pressure has been achieved and packer assembly 102 is securely anchored in place, service tool 100 can then be released from the packer assembly 102 by pulling the work string 28 upward. Additionally, prior to pulling work string 28 and service tool 100 out of wellbore 22 a formation conditioning or sand control operation may be preformed such as a high rate water pack, a frac pack, a gravel pack or the like. According to the foregoing arrangement, service tool 100 attaches to packer assembly 102 in such a way that packer assembly 102 can be run, set and service tool 100 released from packer assembly 102 without any kind of rotation of service tool 100. The hang load is transferred from the separation shear pins 104 by the anti-preset lugs 160. Accordingly, any weight hanging below packer assembly 102 is not applied to separation shear pins 104 during the run-in procedure. Anti-preset lugs 106 are locked in the supporting position during transit by the set of shear pins 184 which lock operating piston extension 156 to service tool mandrel 108. Movement of operating piston 154 in response to the transfer of hydraulic fluid from hydraulic fluid chamber 134 through hydraulic fluid passageway 136 into hydraulic fluid reservoir 194 causes pins 184 to shear, such that collet 162, which holds anti-preset lugs 160 in place, becomes unsupported, thereby permitting collet 162 to carry anti-preset lugs 160 to a new position which permits anti-preset lugs 160 to retract, thereby transferring the hang weight to separation shear pins 104. Continued movement of operating piston 154 downwardly brings sleeve 168 of service tool 100 to bear against setting sleeve extension 166 of packer assembly 102, thereby moving the outer parts of packer assembly 102 relative to packer assembly mandrel 106, and in doing so, expanding seal elements 190 and setting slips 192. After slips 192 have been securely set and annular seal elements 190 have been expanded, separation pins 104 are sheared. Movement of service tool 100 is then possible by straight up or down movement of work string 28 at the surface. As a result, the unique service tool 100 of the present invention provides for remote actuation of a hydraulically controllable device such as packer assembly 102. Remote actuation is achieved utilizing surface installation 38 to generate a signal that is received by transducer 136 of hydraulic power unit 110. This allows for the highly reliable use of hydraulic fluid transfer to operate the hydraulically controllable device without axial or rotational reciprocation of service tool 100 and without the need to drop a ball down through work string 22 or run a hydraulic line from the surface. Even though the service tool of the present invention has been described with reference to operating packer assembly 102 using hydraulic power unit 110 to axially shift operating piston 154, among other components, it should be noted by one skilled in the art that the service tool of the present invention is equally well-suited for actuating other hydraulically controllable downhole devices. For example, the service tool of the present invention may be used to rotatably operate components in a downhole device in order to achieve a desired result. Similarly, the service tool of the present invention may be used to hydraulically initiate the actuation of a valve from either the closed position to the open position or the open position to the closed position, to hydraulically initiate the shifting of a sliding sleeve or to hydraulically initiate the actuation of similarly operated downhole devices. It will be appreciated that the invention described above may be modified.

Claims: A method for actuating a downhole device (102) comprising the steps of: sending a signal to a downhole electronics package (138); establishing a communication path between a self-contained downhole hydraulic fluid source and the downhole device in response to the signal; transmitting a hydraulic fluid from the self-contained downhole hydraulic fluid source (134) to the downhole device (102) through the communication path; and actuating the downhole device (102) in response to the hydraulic fluid, characterised in that the step of transmitting a hydraulic fluid comprises utilising hydrostatic pressure from an annulus surrounding the downhole device (102) to urge the hydraulic fluid from the self-contained downhole hydraulic fluid source to the downhole device (102). A method according to claim 1, wherein the step of transmitting hydraulic pressure further comprises the step of operating a valve (144) from a closed position to an open position. A method according to claim 1 or 2, wherein the step of actuating the downhole device (102) further comprises setting the downhole device (102). A method according to any preceding claim, further comprising the step, simultaneous with said transmitting step, of compressing air in an air chamber (118) to dampen the response to the hydrostatic pressure. A method according to any preceding claim, wherein the step of sending the signal comprises sending an acoustic signal from a surface installation (38) to the downhole electronics package (138). An apparatus (100) for actuating a hydraulically controllable device (102) disposed in a wellbore (22) comprising: a self-contained downhole hydraulic fluid source (134) storing hydraulic fluid proximate the hydraulically controllable device (102); a hydraulic fluid passageway (136) providing a communication path between the self-contained downhole hydraulic fluid source (134) and the hydraulically controllable device (102); a valve (144) disposed within the hydraulic fluid passageway (136); and a downhole electronics package (138) receiving a signal from the surface to operate the valve (144) from a closed position to an open position, thereby transmitting hydraulic pressure from the downhole hydraulic fluid source (134) to the hydraulically controllable device (102); characterised in that the device utilises hydrostatic pressure from an annulus surrounding the hydraulically controllable device to urge the hydraulic fluid from the self-contained downhole hydraulic fluid source to the hydraulically controllable device (102), thereby actuating the hydraulically controllable device (102). Apparatus (100) according to claim 6, wherein the hydraulic fluid source (134) further comprises a housing and a sleeve slidably disposed about the housing, the sleeve and the housing defining a hydraulic fluid chamber therebetween having hydraulic fluid contained therein, the sleeve operating from a first position to a second position relative to the housing in response to hydrostatic pressure once the valve (144) is operated from the closed position to the open position. Apparatus according to claim 7, wherein the sleeve and the housing further define an air chamber (118) therebetween having air contained therein. An apparatus according to claim 8, wherein operation of the valve (144) from the closed position to the open position allows the sleeve to operate from a first position to a second position relative to the housing in response to hydrostatic pressure in the annulus such that the air in the air chamber is compressed to dampen the movement of the sleeve from the first position to the second position, and simultaneously the hydraulic fluid in the hydraulic fluid chamber is urged from the self-contained downhole hydraulic fluid source (134) to the hydraulically controllable device (102), thereby actuating the hydraulically controllable device (102).

Inventors: GRIGSBY TOMMY F, MULLEN BRYON D, GRIGSBY, TOMMY F., MULLEN, BRYON D.
Applicants: HALLIBURTON ENERGY SERV INC, HALLIBURTON ENERGY SERVICES, INC.
Application year: 1999
Main classification: E21B33
IPC codes: E21B33, E21B23