Patent Application
20170067313
The field of the invention is methods for plugging and abandoning wells and more particularly methods that allow multiple operations in a single trip including among other steps running and setting a bridge plug, perforation, washing the perforations, delivering cement under pressure into the perforations and pulling the bottom hole assembly from the location without swabbing the well.
In many instances where a well has to be plugged and abandoned a series of steps are taken to build what amounts to a cement plug but the procedure has in the past been done in a series of discrete steps. One way was to run a perforating gun below a packer and fire the gun and inject cement into the newly created perforations as shown in U.S. Pat. No. 5,372,298. Pressure set washing tools for perforations are shown in U.S. Pat. No. 4,279,306. Systems that run a perforating gun between spaced plugs and release the lower plug to perforate and then set the upper plug to pump cement between the plugs is shown in GB 2414492 A1.
The plugging and abandonment requirements have changed over time and currently the basic steps are to set a bridge plug to act as a lower cement retainer and then perforate the cased hole. When perforating is complete the perforations have to be cleaned before the cement is delivered. The excess cement needs to be circulated out and it is preferred that the cement is squeezed into the perforations to anchor the plug that extends into the main bore. The perforating gun can either be dropped or retrieved before cementing. The bottom hole assembly used in the cement delivery then needs to be pulled out of the hole. While equipment exists to accomplish many of these tasks individually the use of discrete equipment for specific functions to be performed in a precise order has necessitated the use of multiple trips. Depending on the well depth and surface location these multiple trips necessitated additional rig time that as some locations can run up to hundreds of thousands of US dollars a day. Accordingly, there is a need for devices that facilitate moving from one procedure to the next in the same trip to save rig time and completion costs. Those skilled in the art will better appreciate the various aspects of the invention with regard to the equipment and methods that allow an array of completion procedures to be conducted in one trip from a review of the detailed description of the preferred embodiment and the associated figures while appreciating that the full scope of the invention is to be determined from the appended claims.
A bottom hole assembly (BHA) enables a one trip procedure to set a bridge plug and release from that bridge plug with the BHA. A perforating gun is fired and a straddle tool above the gun in repositioned to wash the perforations as the opposed packer cups are moved along the perforations. At the end of the washing step a dropped ball closes a circulation port above the upper packer cups and the ball seat is blown out. A disconnect releases the lower part of the straddle tool with the lower packer cups that are uphole oriented. Cement can now be delivered past the upper packer cups and pressurized to squeeze the cement into the perforations using the upper cups to hold the pressure. Another ported sub above the upper cups has a port opened to prevent swabbing as the BHA is removed.
The invention is a drill pipe string (11)-borne borehole assembly (10) comprising a washing tool assembly (18), comprising:
Referring to
The one trip method works by virtue of running in the BHA 10 into a cased (11) hole, for example. The bridge plug 12 and its plug actuator 14 are placed far enough below the perforations to be made by the gun 16 so that when the gun 16 later is dropped, the gun 16 will be far enough below the perforations formed so as to not interfere with the step of washing through the perforations that comes later. When the bridge plug 12, which is of a type known in the art, is properly positioned the plug actuator 14 is energized, preferably with pressure, and the actuation of the plug also causes preferably a second disconnector (13) to release the actuator 14 from the gun 16 so that the BHA 10 can be repositioned to properly position the perforating gun 16 to one or more positions for conducting the perforation. When the gun 16 is properly positioned and set off to create the perforations the wash tool assembly is then positioned either near the top or near the bottom of the section of the casing wherin perforations have just been made by the gun 16, and the fluid from the surface is pumped through ports 30 that are between cups 26 and 34 such that pressure driven fluid at high velocity can be flushed out through the perforations to clean them and the annulus by removing debris from them with the fluid going into the perforations and coming out in the casing main bore either below cup 24 or above cup 36. The fluid that comes out below cup 24 may then enter ports 22 and pass up through passage 42 on the way to communicating with ports 40 that are above cup 36. It should be noted that the main bore passage (51) ends at ports 30 that before disconnection at disconnector (32) allows surface pumping to reach ports 30 for the washing procedure that preferably takes place as the BHA 10 moving axially in the borehole along the perforations. Again the direction of the washing tool assembly (18) can be top down or bottom up or any other pattern as long as the entire span of perforations gets exposed to the fluid jet stream that comes out of the ports 30.
At the conclusion of the washing of the perforation that is determined by a number of factors such as how many passes were made with the wash tool assembly 18, or the nature of the fluid that is returning, for example, the next big step is to pump cement or some other seal material. In order to do that two things occur. The ports 40 need to be closed and a large passage (54) needs to be opened for the pumped cement at a location where the pumped cement can be pressurized into the perforations after delivery. To do this the internal sleeve in sub 40 that is shifted by a ball landing on a seat where the seat gets blown out after shifting is actuated with pressure on the seated ball. The ports 40 are then closed and the passage for the cement is back to full bore (51) as the ball and seat have been blown out. Prior to the closing of ports 40 the disconnector 32 is actuated with internal pressure on another barrier that lands on a seat near disconnector 32. Thus, the order of operations is to part the disconnect 32 at a location between the cups 26 and 34 so that now the main passage (51) in the perforation wash tool 18 is open at aperture (54) through the now open upper half of disconnector 32, and the smaller ports 30 that directed the fluid jetting for cleaning the perforations do not have to conduct the cement or other seal material.
Once the
When the requisite volume of cement has been pumped or the pressure builds to a predetermined point indicating the perforations are full as is the bore the next step is to open ports 46 on pump out sub 44 so that excess cement can be circulated out. The opening of ports 46 also prevents well swabbing as flow from above cup 36 can get out below cup 34 through open end 52.
Optionally, at a later time if there is a desire to reopen the well, the cement in the borehole can be drilled out in a separate trip and a cement bond log can be run to determine the integrity of the cement in the perforations 52.
The tool 18 is moved as the cement is pumped out through the full-bore aperture (54) to push the cement into the entire interval. The bridge plug 12 is set far enough below the perforation so that when the disconnect 32 separates that portion of the BHA 10 that drops is still laying well below the perforations 52 so as to not interfere with subsequent cementing or later production from those perforations if they are to be reopened for any reason. Despite the separation between the cups 26 and 34 when the disconnect 32 is operated the upper cups 34 and 36 still function as a pressure retainer as does lower cup 26 backed up with cup 24. The tool 18 is unique in that it serves multiple function of jetting the perforations clean through ports 30 at high fluid velocities but is then reconfigured by coming apart at the disconnect (32) between opposed cups in such a way as to open the aperture (54) with a bigger flow channel (51) for the cement to shorten the cementing time and the pumping power required to deliver the cement. This tool 18 also has a bypass from above cup 36 at ports 40 through to below cup 24 at ports 22. This bypass is independent of the passage that directs wash fluid to ports 30 when tool 18 is intact and allows large bore flow of cement out lower end aperture (54) after the disconnect 32 is operated.
While packer cups are discussed as the seals other types of seals are envisioned such as inflatable or mechanically or hydraulically set resettable packers, for example. An advantage of the packer cups is that even when released they have a possibility to hold cement pressure and even if the lower cups 24 and 26 do not hold there is still the bridge plug (12) as a backup. While the tool 18 in the background art is illustrated in a plug and abandon method, the tool 18 has a new application wherein different flow regimes are needed for different functions at different times while saving a trip out of the hole to accomplish both functions.
Those skilled in the art will appreciate that the present one trip method is illustrated where a part of the well is isolated with a packer or bridge plug (12). The perforations are formed and then cleaned with a wash tool (18) that flushes fluid out through the perforations between spaced barriers, the lower and upper swab cups (24, 26, 34, 36) as the assembly (18) is moved to allow washing through all the perforations in a desired direction while providing a bypass path around the spaced isolators for return fluid to the surface around the tool interval between the spaced seals. The bypass (42) upper port (40) is then closed and the washing tool assembly (18) is split at the disconnector (32) between the seals to open a large flow passage (54) for the subsequent pumping out of cement with any potential bypass paths (40) around the top seals that remain with the BHA closed off The cement is squeezed out and through the perforations using the upper seals (34, 36) still with the BHA to retain pressure up to about 5000 PSI to ensure good cement penetration into the perforations. The lower seals even though dropped by the time cement is pumped, may still hold pressure but if they don't, the bridge plug is there for that purpose. The pump out sub is then activated and after picking up the excess cement can be circulated out and swabbing of the well is prevented because the open port on top of the upper seal can be a bypass through the upper packer cups because the path is open to lower end 54.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/NO2014/000010 | 1/31/2014 | WO | 00 |
