SYSTEM

BACKGROUND OF INVENTION

[0001] In many down-hole operations conducted in the oil and gas exploration and extraction industry, “lubricators” are used to manage well pressure when it becomes necessary to access the pressurized well. A lubricator is a high-pressure pipe fitted to the top of a wellhead, which is often referred to as a “Christmas tree,” so that down-hole tools, as well as other related items, can be inserted into and removed from a high- pressure well. Typically, each stage of the well includes valves to control pressure flow through the system.

[0002] Referring to Figure 1, a general schematic of a wellhead having a lubricator is shown. The lubricator 100 is installed at the top of the wellhead 102. The lubricator 100 includes lubricator upper and lower valves 104. The upper and lower valves 104 are used to control pressure flow through the lubricator 100. To facilitate insertion and removal operations, the lubricator 100 is installed onto the wellhead 102. The upper and lower valves 104 can be opened and closed to equalize the lubricator 100 to wellbore pressure or isolate the pressure within the lubricator 100 from the wellbore pressure. When the wellbore pressure is equalized the lubricator 100, down-hole tools/items can be inserted into and removed from the well. When the lubricator 100 is isolated from the wellbore pressure and any pressure within the lubricator 100 has been bled off, down-hole tools/items can be inserted into or removed from the lubricator 100.

[0003] A Back-Pressure Valve (BPV) is a type of check valve used to isolate pressures at a wellhead or between other stages of the well. A BPV is designed to hold pressure from below as a mechanical barrier, however, the BPV enables fluids to be pumped from above, which may be necessary for well control cases. Typically, a BPV is installed at the tubing hanger, i.e., a device attached to the topmost tubing joint in the wellhead to support the tubing string above the wellhead. [0004] Referring to Figure 2, a typical BPV is shown. The BPV 200 includes a body 202 housing a valve 204, spring 206, and valve stem 208. The exterior of the body 202 includes threads 210 at the maximum outer diameter, as well as a seal ring 212. Often, a BPV is employed between a tubing hanger and a lubricator as a means of sealing the pressure at the wellhead when performing access operations to a pressurized well.

SUMMARY OF INVENTION

[0005] In one or more embodiments, the invention relates to an automated Back Pressure Valve (BPV) lubricator system comprising: a lubricator comprising a lubricator shaft terminated in a BPV lubricator connection; one or more hydraulic pistons attached to the lubricator, wherein the one or more hydraulic pistons, when actuated, raise or lower the lubricator shaft; a hydraulic motor attached to the lubricator shaft, wherein the hydraulic motor, when rotated, rotate the lubricator shaft clockwise or counter-clockwise; and a control panel hydraulically connected to the one or more hydraulic pistons and hydraulic motor, wherein the control panel allows actuation of the one or more hydraulic pistons and rotation of the hydraulic motor.

[0006] In one or more embodiments, the invention relates to an automated Back Pressure Valve (BPV) lubricator system comprising: a lubricator comprising a lubricator shaft terminated in a BPV lubricator connection; at least two hydraulic pistons attached to the lubricator, wherein the at least two hydraulic pistons, when actuated, raise or lower the lubricator shaft; a hydraulic motor attached to the lubricator shaft, wherein the hydraulic motor, when rotated, rotate the lubricator shaft clockwise or counter-clockwise; a control panel hydraulically connected to the at least two hydraulic pistons and hydraulic motor, wherein the control panel allows actuation of the at least two hydraulic pistons and rotation of the hydraulic motor; a support plate attached to the lubricator shaft at the end distal from the BPV lubricator connection, wherein support plate is further attached to the at least two hydraulic pistons and the hydraulic motor such that actuation of the at least two hydraulic pistons raise or lower the support plate, lubricator shaft, and hydraulic motor simultaneously; a bearing disposed between the hydraulic motor and the lubricator shaft; and at least one digital component for sensing at least one of torque, pressure, and position of the lubricator shaft, the hydraulic pistons, or the hydraulic motor, wherein the control panel comprises: at least one analog component for actuating the one or more hydraulic pistons or rotating of the hydraulic motor; at least one digital component for actuating the one or more hydraulic pistons or rotating of the hydraulic motor; and an electronic display for displaying data from the at least one digital component, wherein the data sensed by the at least one digital component is communicated to the control panel and displayed on the electronic display.

[0007] In one or more embodiments, the invention relates to a method of controlling engagement/disengagement of a Back Pressure Valve (BPV) lubricator system comprising a lubricator comprising a lubricator shaft terminated in a BPV lubricator connection, the method comprising: attaching one or more hydraulic pistons to the lubricator such that, when actuated, the one or more hydraulic pistons raise or lower the lubricator shaft; attaching a hydraulic motor to the lubricator shaft such that, when rotated, the hydraulic motor rotates the lubricator shaft clockwise or counter-clockwise; and hydraulically connecting a control panel to the one or more hydraulic pistons and hydraulic motor such that the control panel allows actuation of the one or more hydraulic pistons and rotation of the hydraulic motor, wherein, for engagement, the hydraulic pistons are first actuated so as to mate the BPV lubricator connection with a tubing hanger of a wellhead and then, upon mating of the BPV lubricator connection with the tubing hanger of the wellhead, the hydraulic motor is rotated to make-up a threaded connection between the BPV lubricator connection and the tubing hanger of the wellhead; wherein, for disengagement, the hydraulic motor is first rotated so as to breakout the threaded connection between the BPV lubricator connection and the tubing hanger of the wellhead and then, upon break-out of the BPV lubricator connection with the tubing hanger of the wellhead, the hydraulic pistons are actuated so as to separate the BPV lubricator connection from the tubing hanger of the wellhead.

[0008] Other aspects and advantages of the invention will be apparent from the following description and the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is a general schematic of a wellhead having a lubricator.

[0010] Figure 2 shows a typical Back Pressure Valve (BPV).

[0011] Figure 3 is a schematic of a lubricator system for attachment to the tubing hanger of a wellhead in accordance with one or more embodiments of the invention.

[0012] Figure 4 shows a flow chart of control of the BPV lubricator system operations.

[0013] Figure 5 is a block diagram of the BPV lubricator system components.

DETAILED DESCRIPTION

[0014] A Back- Pressure Valve (BPV) can be engaged with a lubricator and then operated (up and down) hydraulically to mate with the tubing hanger of the wellhead. However, upon mating, the lubricator shaft needs to be torqued manually once reaching the top of tubing hanger in order to tighten the BPV into position. This torqueing operation usually requires a minimum of five employees to perform. Two of these employees must be on the wellhead platform to manually rotate (torque) the lubricator shaft and to operate the control panel of the hydraulics, respectively. Any operations requiring employees to be on the wellhead platform exposes them to risk. Further, the torqueing operation can often take two hours to set or retrieve the BPV, and requires rig-up and rig-down equipment. Further, the operation requires special trucks or cranes because of the long length of the lubricator. The torqueing operation is considered “high maintenance,” as it also requires many spare parts to be available.

[0015] One or more embodiments of the invention relate to a design related to installation of a hydraulic rotary pump on a lubricator shaft to rotate a BPV hydraulically, which will minimize the need of human intervention during operations. Additionally, in one or more embodiments, two hydraulic pistons move the shaft up/down with respect to the tubing hanger, and the design of the control panel may be modified to use a digital system to operate the pistons and control the rotation of the pump. The digital system may include digital gauges and controls that allow settings to be maintained during the setting and retrieval of BPV operations.

[0016] Referring to Figure 3, a schematic of a lubricator system for attachment to the tubing hanger of a wellhead is shown. The lubricator system 300 includes a BPV lubricator connection 302 for engaging with the tubing hanger of the wellhead. The BPV lubricator connection 302 is installed on the lubricator shaft 304, which passes through packing 306. While two packing elements are shown in the figure, those skilled in the art will appreciate that one packing element or more than two packing element may be appropriate in different conditions. The packing 306 is used to seal the wellhead pressure around the lubricator shaft 304. Typically, the packing 306 includes a packing knot 307 at the top that holds the lubricator shaft 304 in place so as to prevent any well pressure from coming out of the lubricator system 300. The lubricator shaft 304 is a solid and heavy duty rod (typically, made of chrome, nickel, or stainless steel) used to run through the tubing hanger into the wellhead to set or retrieve the BPV lubricator connection 302. In one or more embodiments, the lubricator shaft 304 has a length of 120 inches and an outer diameter of 1.625 inches, and is rated for H2S / CO2 service.

[0017] Also, a control panel 308, hydraulic pistons 310, and hydraulic motor 312 are connected to the lubricator system 300. The control panel 308 is in communication with the hydraulic pistons 310 and hydraulic motor 312 via hydraulic hoses 314. The control panel 308 controls and transfers the hydraulic pressure energy from a hydraulic power unit to activate the hydraulic pistons 310 and hydraulic motors 312 via hydraulic hoses 314. The control panel 308 includes digital and analog control components, actuators, processors, and the like in order to monitor hydraulic pressure gauges during setting or retrieving operations. In one or more embodiments, the hydraulic control panel 308 is disposed between a conventional hydraulic power system and the hydraulic elements (i.e., hydraulic pistons 310 and hydraulic motor 312) of the BPV lubricator system 300.

[0018] Hydraulic pistons 310 and hydraulic motor 312 are mounted to a support plate 316. The support plate 316 is used to support hydraulic pistons 310, hydraulic motor 312, and the lubricator shaft 304. Based on the control panel operations, the hydraulic pistons 310 are capable of simultaneously, hydraulically moving the support plate 316 up and down. Thereby, the hydraulic pistons 310 move the lubricator shaft 304 up and down during setting or retrieving the BPV lubricator connection 302. Using multiple hydraulic pistons can advantageously centralize the movement of the lubricator shaft 304 during up and down movements of the support plate 316, which helps avoid bending of the shaft and ensuring shaft integrity. In one or more embodiments, the hydraulic pistons 310 have a length that is the same as a length of the lubricator shaft 304.

[0019] Based on the control panel operations, hydraulic motor 312 is capable of rotating the lubricator shaft 304, typically via a bearing 313. The hydraulic motor 312 is used to rotate the lubricator shaft 304 in a clockwise or counter-clockwise directions to tighten/set or loosen the BPV lubricator connection 302 in the well tubing hanger of the wellhead. Those skilled in the art will appreciate that the direction of rotation of the hydraulic motor, i.e., clockwise or counter-clockwise, may result in either tightening or loosening of the connection depending on thread configuration. In one or more embodiments, a bearing 313 is used between the hydraulic motor 312 and the lubricator shaft 304 to provide flexibility to the shaft while rotating to set or retrieve the BPV lubricator connection 302 in the well tubing hanger of the wellhead. In one or more embodiments, the BPV lubricator connection 302 is a BPV engaged with a lubricator.

[0020] Figure 4 shows a flow chart of control of the BPV lubricator system engagement/disengagement operations. As shown, the first step 400 involves an operator selecting engagement or disengagement operation at the control panel of the BPV lubricator system. If the control panel is digital, then a display of the controls may be modified based on the selected operation. Alternatively, if the control panel is analog, the operator simply proceeds with engagement or disengagement operations based on the operation to be performed.

[0021] When engagement operations are selected in the initial step 400, the control panel displays the engagement controls 401 in the case of a digital control panel. In the engagement sequence, first the control panel is used to actuate the hydraulic pistons 403 to lower the BPV lubricator system such that BPV lubricator connection mates with the tubing hanger of the wellhead. Once mating has occurred, the control panel is used to rotate the hydraulic motor 405, thereby tightening the BPV lubricator connection within tubing hanger of the wellhead. The control panel may include gauges or an electronic display of readouts from sensors that indicate the torque of the rotated BPV lubricator connection so that a complete make-up with tubing hanger of the wellhead can be ensured. In embodiments including digital control panels, display elements such as red or green make-up indicators may also be displayed.

[0022] Once the BPV lubricator connection is confirmed with the tubing hanger of the wellhead, the pressure within the lubricator can be equalized with the wellhead pressure 407 and wellhead valves can be confirmed as opened 409. As with other parts of the operation, if the control panel is digital, valve open/close indicators may be displayed, or the operator may confirm the open/close status from gauges, the positions of levers, or the like. Thus, the engagement process is successfully completed and, in the case of a control panel with an electronic display, a successful engagement indicator may be displayed 411. With the BPV lubricator system successfully engaged, down-hole tools, or other down-hole items, may be inserted from or removed to the lubricator from the wellbore.

[0023] When disengagement operations are selected in the initial step 400, the control panel displays the disengagement controls 402 in the case of a digital control panel. In the disengagement sequence, first the control panel is used to determine that the wellhead valves are closed and the lubricator is isolated from the wellbore pressure 404. As with other parts of the operation, if the control panel is digital, valve open/close indicators may be displayed, or the operator may confirm the open/close status from gauges, the positions of levers, or the like. Once the wellhead valves are confirmed closed 404, the lubricator pressure is bled off 406 and the control panel is used to rotate the hydraulic motor 408, thereby loosening the BPV lubricator connection with the tubing hanger of the wellhead. Again, the control panel may include gauges or an electronic display of readouts from sensors that indicate the torque of the rotated BPV lubricator connection so that a complete break-out with tubing hanger of the wellhead can be ensured. In embodiments including digital control panels, display elements such as red or green make-up indicators may also be displayed.

[0024] Once break-out of the BPV lubricator connection has occurred, the control panel is used to actuate the hydraulic pistons 403 to raise the BPV lubricator system such that BPV lubricator connection separates from the tubing hanger of the wellhead. As with other parts of the operation, if the control panel is digital, separation indicators may be displayed based on sensor readouts, or the operator may confirm the separation visually. Thus, the disengagement process is successfully completed and, in the case of a control panel with an electronic display, a successful engagement indicator may be displayed 412. With the BPV lubricator system successfully disengaged, down-hole tools, or other down-hole items, removed from the wellbore to the lubricator, if any, may be removed from the lubricator.

[0025] Referring to Figure 5, a block diagram of the BPV lubricator system components is shown. As the operation of the various components has been described above with respect to embodiments of the present invention, those descriptions are not repeated here and only the general system components and communication is discussed. As can be seen, a BPV lubricator system 500 in accordance with one or more embodiments of the present invention includes a BPV lubricator tool 502 in communication with a control panel 504 for controlling the engagement/disengagement operations. As discussed above, the control panel 504 may also be in communication with a hydraulic power system 506 to facilitate the hydraulic operations being performed.

[0026] The BPV lubricator tool 502 includes a lubricator 508, a BPV lubricator connection 510, one or more hydraulic piston(s) 512, and a hydraulic motor 514. Also, depending on the type of control panel 504 employed, the BPV lubricator tool may include one or more digital sensors to readout various data to control panel facilitate operational display indicators. In one or more embodiments, the control panel 504 includes at least one of various analog components 518 (e.g., gauges, levers, switches, buttons, and the like), digital control components 520 (e.g., digital sensors, actuators, touch pads, and the like), one or more processors 522, and an electronic display 524. As those skilled in the art will appreciate, the control panel 504 may be in communication with the BPV lubricator tool 502 and the hydraulic power system 506 hydraulically and/or using digital/analog signals.

[0027] Advantages of one or more embodiments of the invention may include one or more of the following. By transforming from a manual operation to an automated system, efficiency is increased, activity-tracking is improved, and better troubleshooting is possible. The required manpower for the operation is reduced from typically five operators. The system is easy to operate and automated, which improves overall safety on the wellhead platform. Elimination and/or minimization of human intervention during shaft torqueing avoids over-torqueing of the shaft and potential damage to the shaft by the wrench due to operator error.

[0028] While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. Accordingly, the scope of the invention should be limited only by the attached claims.