Patent Application
20130181147
This invention relates generally to oil well production equipment, and more particularly to a new and useful blowout preventer for use on an oil or other well driven into an underground formation.
A blowout preventer (BOP) is a device typically used to seal off or close off an oil pumping well. It acts somewhat similar to a valve and generally has apposing rams that move together to seal off well pressure from within the well to atmosphere. The majority of all BOP's on production wells will have a polish rod extending through their center during use. The polish rod may have a reciprocation motion when used in a pump jack application or a rotating motion when used in a PCP (progressing cavity pump) application. The ram body is typically made of steel and contains an elastomer seal that squeezes against the polish rod and also squeezes against the inside of the BOP to seal pressure in the well. With the rams in their open position oil is allowed to flow up through the BOP and exit through a flow line. With the rams closed the well is shut off and flow is contained.
A typical oil well is made up of casing which runs the length of the well and has a casing bowl attached to it above the ground. The exterior of the casing is cemented to the drilled oil well hole to provide a tight seal preventing any well pressure from leaking to the surface. Inside the casing is tubing that runs the length of the oil well down to the pump or motor at the bottom of the well. The top of the tubing is attached to a tubing hanger which seals the tubing from well pressure and is usually found in the tubing head just below the BOP. When the well is pumping either by a pump jack or a PCP the oil flows up through the tubing and in to the BOP, where it continues its way through flow lines to a tank, reservoir or pipeline.
A common problem with the production of oil is sand. Sand released out of the oil settles and often causes pumps and motors to become plugged, or surrounds the outside of pumps and motors causing a reduction in oil production and/or resulting in the pump becoming locked in place. To release the sand from the well a procedure called a “flush-by” is performed where a hose or coiled tubing is run down through the tubing, or between the tubing and the casing, to allow high pressure liquids (such as water) to flush the sand out. In the case of well having a PCP drive, for the hose or coil tubing to gain access to the inside of the tubing string the drive head must first be removed and the polish rod and connected sucker rods lifted to remove the rotor from the stator to allow the coiled tubing to pass through the stator and permit access to the well at a point below the pump. This is time consuming as the drive head, stuffing box and clamps must be removed, requiring in most the use of cases cranes, boom trucks or other lifting devices. To flush the sand from between the tubing and the casing, or from inside the tubing string, the drive head, clamps, stuffing boxes etc (i.e. the top of the wellhead) must be removed. The BOP must then typically be removed to gain access to the tubing hanger located in the casing bowl. The hanger must be lifted out of the casing bowl and high enough to allow the coil tubing to be inserted into the annulus between the tubing and the casing. The coil tubing can then be inserted the length of the tubing string down to the pump or motor. Some wells also collect high amounts of sand beyond the pump and motor so coiled tubing may have to be inserted further down the well. The hanger and tubing is much heavier than the polish rod, sucker rod and rotor, accordingly larger lifting equipment is often needed at the well site when it is necessary to lift the tubing.
Flush by's are a very important procedure for maximizing oil production, but in many cases they can be time consuming, resulting in increased costs from the perspective of labour, necessary equipment to perform the procedure and down time for the well. The improved BOP of the present invention is designed to save time, and as a result costs, when performing a flush by, and also helps to keep the well head manageable in terms of size, and the number of well head components.
The invention therefore, in one of its aspects, provides an improved blowout preventer that addresses some of the deficiencies of current blowout preventers and that enhances the ability to insert fluid or an elongate member into a well.
In one aspect the invention concerns an improved blowout preventer for a well having a casing extending into an underground formation, said improved blowout preventer comprising a main housing having a generally longitudinally oriented bore therethrough for releasably receiving a pump rod therein; a pair of opposed ram members received within a pair of generally transverse bores within said main housing, said ram members moveable between an engaged position wherein they sealingly engage the pump rod and each other when a pump rod is received through said longitudinal bore, and a disengaged position wherein they are retracted from engaging either the pump rod or each other; and, one or more side entry ports within said main housing, said side entry ports permitting a fluid or elongate member to be inserted into the casing.
For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example, to the accompanying drawings which show the preferred embodiments of the present invention in which:
The present invention may be embodied in a number of different forms. However, the specification and drawings describe and disclose only some of the specific forms of the invention and are not intended to limit the scope of the invention as defined in the claims that follow herein.
The new improved BOP design combines several wellhead servicing procedures that are done on various wellhead components to be completed in the BOP. In the past drive heads, stuffing boxes, polish rod clamps and BOP's had to be unbolted and removed to gain access to the tubing string and sucker rods, rotors, stators, pumps, etc. Such items are typically the main components that have to be replaced over time or that get sanded in and need to be flushed out by a flush-by unit. The improved BOP of the present invention will allow for the servicing and the operation of the wellhead to be contained in one unit. The BOP has a removable stuffing box built into a rod hanger. The rod hanger is preferably situated internally in the top of the BOP with the entrance to the tubing string being through the rod hanger. With the use of seals and lock down screws the rod hanger is sealed and secured to the BOP. The top of the rod hanger receives the shaft of a PCP drive head or some form of rotating input shaft that transmits rotating torque through the rod hanger to an end of the rod hanger shaft which is connected to the sucker rods for driving a PCP rotor. The BOP rams are able to clamp on the hanger shaft and seal off all well pressure. If desired, a second set of blind rams could be positioned above the sealing rams that could also seal off the well pressure if there were no rods in the center of the BOP. The BOP could also have more than two sets of rams. In addition, the rod input shaft may be connected to a secondary shaft below it, the secondary shaft having a area for the rams to clamp the shaft securely with teeth, spline etc. This shaft would be useful when lifting the rod hanger out of the BOP where the rams would clamp on the secondary rod and secure it to disconnect the rod, hanger shaft. The rod hanger shaft could also be extended and be supported by the rams and sealed and clamped from preventing rotation.
In prior PCP wellheads, drive heads typically have had a rotating polish rod through the center and extending out of the top where a clamp would transmit the rotational torque from the motor to the rotor. This structure can present a hazard to workers. With the improved BOP of the present invention the drive motor only needs to have a shaft engagement in the rod hanger, leaving no rotating members sticking out of the top of the drive motor.
In certain applications the hanger may be hollow and may include a plug for closing off its hollow interior. The plug may be a valve or other mechanism for closing the hollow bore of the rod hanger. Alternately, there could be more than one plug, or a combination of plugs and valves.
The new BOP also receives the tubing hanger below the rams. The tubing hanger is sealed and held in place with lock down screws. In prior wells the tubing hanger would typically be placed in a casing bowl or tubing head. Having the hanger placed in the BOP saves time, since in prior wells the BOP would have to be removed to gain access to the tubing hanger.
The BOP of the present invention has an entry port that allows fluid, coiled tubing, a cable, probe or other elongate member to enter the BOP on the side or face with an angle of entry angle that in most cases would typically be no greater than 30 degrees. In some cases (for example where the entry port is used for inserting probes or sensors) the angle of entry could be greater. When inserted through the entry port the coil tubing (fluid or other elongate member) will be allowed to travel down the well between the casing and the tubing string, and/or down the tubing. It will be appreciated from a thorough understanding of the invention, and from a review of the attached drawings, that depending on the particular needs and depending on the nature of a particular well, the BOP can be constructed with one or more entry ports. Those entry ports may also be at different locations about the main body of the BOP, may have different angles of inclination and may terminate at either the bottom surface of the BOP or within the longitudinal bore through the BOP main housing. Hence, depending upon the relative positioning of the BOP and the tubing string hanger, and depending on the nature and point of termination of the entry ports, the entry ports may allow direct access to the interior of the tubing string (for example, see
While the entry port would commonly be positioned above the rams, it could also be located below the rams and/or below the rams and tubing hanger. The entry port saves time as the hanger does not have to be removed or lifted from the BOP to perform a flush by operation. This improved BOP also permits for a reduction in operator error at a well site by reducing the need for undoing and redoing connections. Undoing and redoing connections also often requires the replacement of gaskets and can be time consuming. The improved BOP also helps to reduce wellhead height which has advantages in terms of strain on wellhead equipment in non-vertical wells.
It is to be understood that what has been described are the preferred embodiments of the invention and that it may be possible to make variations to these embodiments while staying within the broad scope of the invention. Some of these variations have been discussed while others will be readily apparent to those skilled in the art. For example, while the attached Figures show the insertion of coiled tubing through the entry ports in the BOP, it will be appreciated that those ports could be used for direct fluid injection or to receive hoses, tubing, cables, wires, probes, sensors or a wide variety of other elongate or other members with which there may be a desire to access the interior of the tubing string and/or the annulus between the tubing string and the casing.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/CA2011/001048 | 9/16/2011 | WO | 00 | 3/15/2013 |
| Number | Date | Country | |
|---|---|---|---|
| 61383613 | Sep 2010 | US |
