Patent Application
20230023843
This invention relates to devices for draining fluids from a tubing string in a hydrocarbon production well. Tubing drains allow fluids to drain from the tubing string of a well. Among other purposes, draining fluid from the tubing string allows the tubing to be removed from a well without pulling the tubing “wet”, which occurs when there is an obstruction in the tubing which prevents the fluid from draining out of the bottom of the tubing. For example, if the well is produced with a rod pump and the rods have parted leaving a pump or plunger at the bottom of the tubing string, the tubing will stand full of fluid requiring the well to be pulled wet, unless a drain can be actuated which allows the fluid to escape from the inside of the tubing into the casing-tubing annulus. Pulling the tubing wet can result in produced fluid being spilled on the ground surface as well as potentially spraying the production rig crew as the tubing joints are unscrewed. Such releases may violate a variety of laws and regulations, including those pertaining to environmental protection and occupational health and safety.
Tubing drains may be either activated by manipulation of the tubing, typically by rotation, or by applying pressure to the tubing string to a sufficiently high pressure to burst one or more rupture discs contained within the tubing drain. In the case of the hydraulic drain a pressure truck or high-pressure surface pump must be employed to apply the hydraulic pressure required to open the drain. In the case of the known mechanical drains, with one variety the sucker rod string is first pulled with a pulling hoist and then a ball, bar or dart is dropped down the tubing to knock out shear pins open the drain. Both of the above mechanisms leave debris in the well, such as remnants of pressure discs and shear pins.
Other types of tubing drains may be opened by rotation of the tubing string. For example, the Applicant herein owns U.S. Pat. No. 10,337,286 which discloses a mechanical drain which may be opened and closed by rotation of the tubing string.
Each type of known drain has operational limitations. For example, there are situations where rotation of the tubing may not be achievable, such as in highly deviated wells or when it is not possible to set a downhole plug required for hydraulically pressurizing the tubing to actuate a hydraulic drain. It is to be noted that there are no known mechanically actuated drains for unanchored tubing strings. A drain actuation device which allows draining of the tubing when these and other situations are present would be beneficial.
Embodiments of the method and apparatus disclosed herein provide a solution to the problems described above. For purposes of this disclosure, the terms “lower,” “bottom,” “downward,” etc., refer to a direction facing toward the bottom of a well and the terms “upper,” “top,” “up,” etc., refer to a direction facing toward the surface. The terms “inward” and “inwardly” refer to a direction facing toward the central axis of the disclosed mechanical drain and the terms “outward” and “outwardly” refer to a direction facing towards the inside wall of the casing string.
An embodiment of the apparatus is utilized in hydrocarbon producing wells for draining a tubing string which is disposed within a length of well casing. Embodiments of the mechanical drain have a tubular member, which may comprise either a single piece mandrel or which may comprise an upper connector member and a lower mandrel member. The tubular member is made up into the tubing string, typically with either a box-to-pin configuration, where the tubular member has a box with internal threads on one end for receiving a threaded male pin and a pin with external threads on the opposing end, a box-to-box configuration where each end of the tubular member has a box with internal threads, or a pin-to-pin configuration where the tubular member has threaded male ends on each end which are made up into adjacent tubing couplings.
The tubular member of the mechanical drain has an axially aligned opening which has an inside diameter which, in accord with oilfield practice, is typically at least as large as the inside diameter of the tubing comprising the tubing string. The axially aligned opening of the tubular member has a central axis which may be, but not necessarily, offset from a central axis of the tubular member.
The tubular member has an outside surface and an inside surface. The inside surface has an upper bore section and a lower bore section which is contiguous with the upper bore section. The lower bore section comprises a drain port extending through the tubular wall from the inside surface to the outside surface. The term “drain port” is defined herein to include multiple ports, each set within the lower bore section. The drain port (or drain ports) may have a diameter ranging from one-half inch to three-quarter inch.
The mechanical drain also has a sleeve member which has a top and a bottom. The sleeve member is configured to be releasably retained within the lower bore section of the tubular member by a plurality of shear pins, which typically are threaded brass screws which extend between the tubular member and the sleeve member. The sleeve member is described as being releasably retained within the lower bore section because shearing of the shear screws will allow the sleeve to be axially moved within the tubular member. The sleeve member is initially disposed across the drain port such that the sleeve member prevents a flow of fluid through the drain port when the sleeve member is retained within the lower bore section. The sleeve member may have O-ring grooves and utilize elastomeric O-rings to provide a fluid-tight seal to prevent fluid flow out of the drain port while the sleeve member is retained in the lower bore section.
The mechanical drain also has a bumper member which is disposed in a first position below the sleeve member. The bumper member is raisable to a second position at which point the bumper member engages the bottom of the sleeve member thereby causing the plurality of shear pins to shear and driving the top of the sleeve member into the upper bore section thereby uncovering the drain port and allowing a fluid to flow through the drain port to an exterior of the mechanically actuated drain. The bumper member may have an upper section which has a configuration which provides for an improved fluid flow in the tubing string around the bumper member. For example, the bumper member may have a fluted or lobed configuration to improve the fluid flow. The bumper member may also comprise an internal threaded portion for connecting to a threaded member, such as a downward facing threaded pin of a sucker rod. Alternatively, the bumper member may have an upper end configured to be engaged by a tool run in on slick line or wire line.
Embodiments of the mechanical drain may comprise a single piece mandrel which comprises both the upper bore section and lower bore section. In the single piece embodiment, once upward force is no longer applied to the bumper member, such as when the rod string above the bumper member separates at a disconnect tool, the sleeve member is retained in the upper bore section of the tubular member by various mechanisms, which may be assisted by the expansion of O-rings on the sleeve member as it is pulled into the upper bore section. This prevents the drain from resealing after the upward force is released on the bumper member.
Alternatively, embodiments of the mechanical drain may comprise a mandrel member having the lower bore section, and an upper connector member, where the upper connector member comprises the upper bore section. In this alternative embodiment, the sleeve member may comprise a plurality of outside diameters in a graduated configuration, with the plurality of outside diameters increasing in size from a smallest outside diameter at the top of the sleeve member and increasing with respect to an axial distance away from the top of the sleeve member (i.e., moving toward the bottom of the sleeve member). With this configuration, the upper bore section has an internal diameter having a wedge configuration with the internal diameter decreasing in size axially toward the upper end. With this embodiment, the graduated configuration of the outside diameters of the sleeve member and the wedge configuration of the internal diameter of the upper bore section cooperatively act to retain the sleeve member in the second position upon the raising of the sleeve member by the bumper member generating an interference fit between the outside diameter of the sleeve and the internal diameter of the upper bore section.
In one application of the invention, a rod string may be utilized to operate a subsurface pump which is set below the mechanical drain, with a portion of the rod string passing through the mechanical drain. In this installation, an embodiment of the mechanical drain has the bumper member depending from a rod of the rod string, where the rod string can be utilized to raise the bumper member from the first position to the second position. Thus, the rod string can be utilized to open the mechanical drain by raising the rod string a particular length.
Embodiments of the invention might be operated by alternative means. For example, an embodiment of the mechanical drain might have a bumper member having an upper member configured to be engaged by a slick line or wire line recovery tool. With this embodiment, an embodiment of the presently disclosed mechanical drain might be utilized to drain tubing of wells which do not utilize rod strings.
Referring specifically to the figures, two basic embodiments of the presently disclosed invention are depicted. The first embodiment 100 of the mechanical drain has a one-piece tubular member 110 or mandrel as depicted in
Second embodiment 200 utilizes a two-piece tubular member 210 which provides looser tolerances between the outside diameter of the sleeve member 250 and the inside diameter of the tubular member, thereby providing an embodiment in which the sleeve member 230 has a smaller inside diameter than the inside diameter of the sleeve member 130 utilized in the one-piece tubular member 110. Each embodiment will have specific benefits depending upon the characteristics of a particular well.
The first embodiment of the mechanical drain 100 is connected at its upper end to a joint of tubing 10 suspended from a string of tubing which extends to the surface of the well. A string of sucker rods may run through the tubing string and extend through the mechanical drain 100 and connect to a pump assembly, such as a plunger for a tubing pump below the mechanical drain 100.
Mechanical drain 100 comprises a tubular member 110, also referred to herein as a single piece mandrel. Tubular member 110 comprises an upper end 112, a lower end 114 and an axially aligned opening 116 extending between the upper end and the lower end. Tubular member 110 has a tubular wall 118 having an inside surface 120 and an outside surface 122. The inside surface has an upper bore section UB and a lower bore section LB which is contiguous with the upper bore section. The lower bore section LB has at least one drain port 124 which extends through the tubular wall 118 from the inside surface 120 to the outside surface 122.
Mechanical drain 100 also comprises a sleeve member 130. Sleeve member 130 is initially disposed within the lower bore section LB and pinned into place in that section as discussed below. When desired, sleeve member 130 may be raised into upper bore section UB by utilizing an upward pulling means.
Mechanical drain 100 also comprises a bumper member 150, shown in greater detail in
As indicated in
Bumper member 150 is disposed in a first position which is below lower bore section LB. The bumper member 150 is raisable to a second position where the bumper member 150 engages the bottom 132 of sleeve member 130 thereby pushing sleeve member 130 into upper bore section LB as depicted in
Sleeve member 130 has a bottom 132 and a top 134.
As illustrated in
As discussed above,
In this embodiment of the mechanical drain 100, once sleeve member 130 is pulled into the upper bore section UB the sleeve member remains in the upper bore section even after the upward force is release, such as when the portion of the rod string above the mechanical drain is disconnected. Although the upper bore section UB has a larger diameter than the lower bore section LB, the dimensional tolerances between the outside diameter of the sleeve member 130 and the inside diameter of the upper bore section of the tubular member 110 are sufficiently tight that once the sleeve member is pulled into the upper bore section the O-rings will expand sufficiently to prevent the sleeve from falling back into the lower bore section LB even after the upward tension is removed from the bumper member 150.
Mechanical drain 200 comprises a tubular member 210 comprising a lower mandrel member 212 and an upper connector member 214. Lower mandrel member 212 has an upper end 216, a lower end 218 and an axially aligned opening 220 extending between the upper end and the lower end. Lower mandrel member 212 has a mandrel member wall 222 having an inside surface 224 and an outside surface 226. The inside surface 224 has a lower bore section LB. The lower bore section LB has at least one drain port 228 which extends through the mandrel member wall 222 from the inside surface 224 to the outside surface 226.
Upper connector member 214 comprises an upper end 230 and a lower end 232. As depicted in
Upper connector member 214 has an inside surface 234 having an upper bore section UB which is adjacent to the lower bore section LB of the lower mandrel member 212. Upper bore section UB comprises an axial section 236 having internal diameter in a wedge configuration with the internal diameter decreasing in size axially upward through the upper bore section UB to a terminus 238 of the upper bore section.
Mechanical drain 200 also comprises a sleeve member 250. Sleeve member 250 is initially disposed within the lower bore section LB and pinned into place in that section as discussed below. When desired, sleeve member 250 may be raised such that the top 252 of sleeve member 250 is shifted into upper bore section UB as depicted in
Bumper member 150 is disposed in a first position which is below lower bore section LB. The bumper member 150 is raisable to a second position where the bumper member 150 engages the bottom 254 of sleeve member 250 thereby pushing sleeve member 250 upward so that the top 252 of sleeve member 250 is moved into upper bore section LB as depicted in
As illustrated in
The top 252 of sleeve member 250 is brought into upper bore section UB by bumper member 150 being pulled from a first position below the lower bore section LB into a second position where the bumper member 150 engages the bottom 254 of sleeve member 250. Further upward pushing of sleeve member 250 causes shear pins 256 to break and allows the top 252 of sleeve member 250 to be pushed into the upper bore section UB by bumper member 150. The upward movement of sleeve member 250 uncovers drain port(s) 228 and allows fluid to exit the tubing by flowing out through the uncovered drain port(s). It is to be noted that when sleeve member 250 is pushed upward with sufficient force to break the shear pins, the shear pin fragments are retained within mandrel member 212 and within the apertures 258 of the sleeve member 250 such that no shear pin fragments end up falling into the wellbore. As with mechanical anchor 100, bumper member 150 may be pulled upward to raise sleeve member 250 either by raising of the rod string or by upward force applied by a slick line or wire line.
In this embodiment of the mechanical drain 200, sleeve member 250 has an outside diameter at top 252 which is at a minimum, but which diameter increases in a step configuration between top 252 and a maximum diameter point 268. This configuration of the sleeve member 250 interacts cooperatively with wedge configuration of upper bore section UB described above to wedge the top of sleeve member into the upper bore section as it is pushed upwardly by bumper member 150 to retain sleeve member 250 in the upper position once the upward force applied to bumper member 150 is stopped, thereby preventing the sleeve member 250 from falling back into the lower bore section LB and covering drain port 228
While the above is a description of various embodiments of the present invention, further modifications may be employed without departing from the spirit and scope of the present invention. Thus the scope of the invention should not be limited according to these factors, but according to the following appended claims.
