Dump Bailer And Lubricator Assembly For Filling The Dump Bailer

Abstract

A dump bailer for being filled with a flowable material in a lubricator assembly and for depositing the flowable material in a wellbore, wherein the dump comprises a filling valve for filling flowable material into the dump bailer and a means for orientation of the dump bailer along a longitudinal axis. The invention also relates to a lubricator assembly configured to allow filling a flowable material into a dump bailer positioned within the lubricator assembly, wherein the lubricator assembly comprises an inlet for injection of flowable material and a guide for providing the dump bailer with a correct position and orientation. The invention further relates to a method for filling a flowable material into a dump bailer positioned within a lubricator assembly and for depositing the flowable material in a wellbore.

Claims

1. Dump bailer for being filled with a flowable material in a lubricator assembly and for depositing the flowable material in a wellbore, the dump bailer comprises: a main chamber divided by a longitudinally displaceable and sealing wiper plug into an upper chamber and a lower chamber for containing the flowable material; a pump for pumping wellbore fluid from a pump inlet to the upper chamber; a first tensioned valve system configured so that, when the pump is active, liquid communication between the pump and the upper chamber is open while liquid communication between the upper chamber and the surroundings is closed, and when the pump is inactive, liquid communication between the pump and the upper chamber is closed while liquid communication between the upper chamber and the surroundings is open; a second tensioned valve system configured so that liquid communication between the lower chamber and an outlet of the dump bailer is open when the pump is active and closed when the pump is inactive; a filling valve for filling flowable material into the lower chamber while preventing flowable material exiting the lower chamber through the filling valve; and a means for orientation of the dump bailer along a longitudinal axis.

2. The dump bailer according to claim 1, wherein the means for orientation of the dump bailer comprises an inclined lower surface for orientating the dump bailer using a guide with a matching inclined surface.

3. The dump bailer according to claim 2, wherein the inclined surface is a part of a mule shoe.

4. The dump bailer according to claim 1, wherein the filling valve is configured to be opened with a dart.

5. The dump bailer according to claim 1, wherein the pump is a positive displacement pump.

6. A lubricator assembly configured to allow filling a flowable material into a dump bailer positioned within the lubricator assembly, the lubricator assembly comprises: an inlet for injection of flowable material through a wall of the lubricator assembly; an inlet sealing mechanism for providing a tight liquid communication between the inlet and a filling valve in the dump bailer; and a guide for providing the dump bailer with a position and an orientation within the lubricator assembly so that the dump bailer filling valve is positioned correctly for the inlet sealing mechanism to provide a tight liquid communication between the inlet and the filling valve, wherein the inlet sealing mechanism and the guide are operable from outside of the lubricator assembly.

7. The lubricator assembly according to claim 6, wherein the guide comprises an inclined surface for matching an inclined lower portion of the dump bailer.

8. The lubricator assembly according to claim 7, wherein a normal of the inclined surface forms an angle relative to a longitudinal axis of the lubricator assembly for matching a mule shoe on the dump bailer.

9. The lubricator assembly according to claim 7, wherein the lubricator assembly further comprises a wash line inlet and a wash line outlet for washing at least a portion of the dump bailer by injecting a cleaning liquid through the wash line inlet and letting the cleaning liquid out of the wash line outlet, and wherein the inclined surface is configured for guiding the cleaning liquid towards the wash line outlet.

10. The lubricator assembly according to claim 6, wherein the inlet sealing mechanism comprises a seal cup which is displaceable within the inlet of the lubricator assembly towards the filling valve of the dump bailer.

11. The lubricator assembly according to claim 6, wherein the lubricator assembly further comprises a dart through the inlet for opening the filling valve of the dump bailer.

12. Method for filling a flowable material into a dump bailer positioned within a lubricator assembly and for depositing the flowable material in a wellbore, the method comprises the steps of: positioning and orienting the dump bailer within the lubricator assembly such that a filling valve of the dump bailer is positioned correctly relative to an inlet of the lubricator assembly; filling the dump bailer with flowable material while the dump bailer is within the lubricator assembly; lowering the dump bailer containing the flowable material into the wellbore at a desired depth; and depositing the flowable material in the wellbore.

13. The method according to claim 12, wherein the method additionally comprises the step of testing at least one valve of the dump bailer while the dump bailer is within the lubricator assembly.

14. The method according to claim 12, wherein the method additionally comprises the step of washing at least a portion of the dump bailer while the dump bailer is within the lubricator assembly.

15. The method according to claim 12, wherein the step of depositing the flowable material in the wellbore comprises simultaneously displacing the dump bailer upwards within the well.

16. The method according to claim 15, wherein the dump bailer comprises a positive displacement pump, and wherein a speed of displacement of the dump bailer is selected to match a deposit rate of the flowable material so that the relative distance between a upper surface of the deposited flowable material and the dump bailer is substantially constant during the step of depositing the flowable material in the wellbore while simultaneously displacing the dump bailer upwards within the well.

17. The method according to claim 16, wherein the method additionally comprises the step of depositing a first portion of the flowable material until a outlet of the dump bailer is covered by the flowable material before the step of depositing the flowable material in the wellbore while simultaneously displacing the dump bailer upwards within the well.

18. The method according to claim 12, wherein the method additionally comprises the step of pulling the dump bailer into the lubricator assembly after the flowable material has been deposited at the desired depth; and repeating the preceding method steps.

19. The method according to claim 18, wherein, for every time the step of lowering the dump bailer containing the flowable material into the wellbore at a desired depth is repeated, the dump bailer is lowered so that a outlet of the dump bailer is immersed into the previously deposited flowable material to such an extent that the outlet of the dump bailer is covered by the previously deposited flowable material, before the step of depositing the flowable material in the wellbore while simultaneously displacing the dump bailer upwards within the well.

Description

[0062] In the following is described an example of a preferred embodiment illustrated in the accompanying drawings, wherein:

[0063] FIG. 1 shows a dump bailer according to the invention;

[0064] FIG. 2 show cross-sectional view of a portion of the dump bailer when filled with flowable material (FIG. 2a), during deposition (FIG. 2b), and when deposition is done (FIG. 2c);

[0065] FIG. 3 shows a lubricator assembly according to the invention mounted on a Christmas tree on an oil rig;

[0066] FIG. 4. shows a cross-sectional view of a portion of the lubricator assembly before (FIG. 4a) and after (FIG. 4b) orientation of the dump bailer in the lubricator assembly.

[0067] FIG. 5 a and b show cross-sectional views of a portion of the lubricator assembly and dump bailer during filling of two embodiments of the dump bailer with flowable material; and

[0068] FIG. 6 shows a method for depositing cement slurry in a wellbore according to the invention.

[0069] In the drawings, the reference numeral 1 indicates a dump bailer according to the invention. Identical reference numerals indicate identical or similar features in the drawings. The drawings are presented in a simplified and schematic manner, and the features therein are not necessarily drawn to scale.

[0070] FIG. 1 shows an overview of a dump bailer 1 comprising a cable head 3 for connection between the dump bailer and the wireline; a depth-measuring tool 5 for measuring the depth of the dump bailer 1, for example a gamma ray logging tool or a casing collar locator; a rotational motor 7 for rotating a shaft of a pump 9; a chamber section 11 comprising the main chamber and the tensioned valve systems; and a mule shoe 13. The mule shoe 13 provides the means for orientation of the dump bailer 1 along its longitudinal axis, as well as an outlet 15 for deposition of flowable material. The chamber section 11 comprises a filling valve 17 for filling the dump bailer 1 with flowable material and a port 19 for liquid communication between the chamber and the surroundings. The pump has an inlet 21 for pumping wellbore fluid into the chamber section 11.

[0071] FIGS. 2a-c show a cross-sectional view of the chamber section 11 and mule shoe 13 when the dump bailer 1 is completely filled with flowable material (FIG. 2a), during deposition of flowable material when the dump bailer 1 is halfway emptied (FIG. 2b), and when the dump bailer 1 is empty (FIG. 2c). The chamber section 11 comprises a main chamber 23 which is divided by a longitudinally displaceable and sealing wiper plug 25 into an upper chamber 27 and a lower chamber 29. As the wiper plug 25 is displaced within the main chamber 23, the volumes of the upper 27 and lower 29 chambers are changed. In FIG. 2a, the wiper plug 25 is at the top of the main chamber 23, whereby the volume of the upper chamber 27 is substantially zero, while the volume of the lower chamber 29 is almost that of the main chamber 23 (apart from the volume of the wiper plug 25). In FIG. 2b the wiper plug 25 has been displaced to the middle of the main chamber 23, whereby the upper 27 and lower 29 chambers have similar volumes. In FIG. 2c the wiper plug 25 has been displaced to the bottom of the main chamber 23 so that the volume of lower chamber 29 is substantially zero while the volume of the upper chamber 27 is almost that of the main chamber 23.

[0072] The chamber section 11 also comprises a first tensioned valve system 31 and a second tensioned valve system 33. The first tensioned valve system 31 comprises a first valve member 35 which is tensioned with a first spring 36 towards the pump 9. In FIGS. 2a and 2c the first valve member 35 is in passive position, whereby it is blocking a port 37 for liquid communication between the pump 9 and the upper chamber 27, while another port 19 for liquid communication between the upper chamber 27 and the surroundings is open. When the pump 9 is pumping, as is the situation in FIG. 2b, the pressure above the first spring-loaded valve member 35 is increased, which causes the first valve member 35 to be displaced in the direction opposite to the spring force and compress the spring 36. When the first spring 36 is compressed, the port 19 for liquid communication between the upper chamber 27 and the surroundings is blocked by the first valve member 35, while the port 37 for liquid communication between the pump 9 and the upper chamber 27 is open. Wellbore fluid is thereby pumped from the surroundings through the pump 9 and port 37 to the upper chamber 27. The increased pressure in the upper chamber 27 will act on the second tensioned valve system 33 through the wiper plug 25 and flowable material in the lower chamber 29.

[0073] The second tensioned valve system 33 comprises a second valve member 41 which is tensioned against the lower chamber 29 with a second spring 43. The area of the second valve member 41 is substantially equal to the area of the wiper plug 25. In FIGS. 2a and 2c the second valve member 41 is in passive position, thereby blocking a port 45 for liquid communication between the lower chamber 29 and the outlet 15 of the dump bailer 1. The force of the second spring 43 should be large enough to avoid that it opens under the weight of the flowable material inside the lower chamber 29, yet small enough to be overcome by the pressure of the pump 9. When the pump 9 is active, as in FIG. 2b, the second valve member 41 is displaced against the force of the second spring 43. This displacement causes the second valve member 41 to reach a position in the second tensioned valve system 33 where channels 47 are carved into the side of the valve housing around the second valve member 41. The flowable material can thereby flow from the lower chamber 29 through the port 45 and channels 47 and out of the outlet 15 for deposition in the wellbore.

[0074] When the wiper plug 25 reaches the bottom of the main chamber 23, as in FIG. 2c, pressure in the upper chamber 27 increases significantly, and the pump 9 is stopped. The first 35 and second 41 valve members then return to their passive state, whereby the ports 37 and 45 are closed as explained above, while the port 19 for fluid communication between the upper chamber 29 and the surroundings is open to avoid trapping pressure in the dump bailer 1. During the entire process shown in FIG. 2a-c, the filling valve 17 is maintained in closed position.

[0075] FIG. 3 shows a lubricator assembly 51 mounted on a Christmas tree 55 installed on an oil rig 53. A hoisting system 57 is connected to a dump bailer 1 (not visible in this figure) within the lubricator assembly 51 through a wireline 59. In addition to the elongated tubing 61 required to contain the dump bailer 1 and the blow-out preventer 63, the lubricator assembly 51 comprises a filling section 65 positioned between the Christmas tree 55 and the blow-out preventer 63 for filling the dump bailer 1 with flowable material while the dump bailer 1 is at wellbore shut-in pressure within the lubricator assembly 51. The filling section 65 is illustrated with more details in FIG. 4.

[0076] FIGS. 4a-b show cross-sectional views of the filling section 65 of the lubricator assembly 51 from FIG. 3, together with a dump bailer 1 (not in sectioned view in FIG. 4). The filling section 65 of the lubricator assembly 51 comprises a guide 67 for positioning and orienting a dump bailer correctly within the lubricator assembly 51. In FIGS. 4a-b the guide comprises an inclined surface 69 for matching the mule shoe 13 of the dump bailer 1. The filling section 65 of the lubricator assembly 51 additionally comprises an inlet 71 for injection of flowable material, a seal cup 72 for sealing around the filling valve 17, and a dart 73 through the centre of the inlet 71. Both the seal cup 72, the dart 73, and the guide 67 can be operated from the outside of the lubricator assembly 51. During operation of the dump bailer 1 in the wellbore, the guide 67, seal cup 72, and dart 73 are in withdrawn positioned from the centre of the lubricator assembly 51 to allow free vertical movement of dump bailer 1. When the dump bailer 1 is to be filled, it is lifted up into the lubricator assembly 51 so that the bottom of the mule shoe 13 is above the guide 67 as shown in FIG. 4a. Then the guide 67 is displaced within the lubricator assembly, and the dump bailer 1 is lowered to land onto the guide 67. Due to the matching inclined surfaces of the guide 67 and the mule show 13, the dump bailer 1 will automatically orient itself within the lubricator assembly 51 as shown in FIG. 4b. When the dump bailer 1 is oriented correctly, the seal cup 72 can be displaced to seal the around the filling valve 17, and the dart 73 can be inserted into the filling valve 17 (not visible in the figure) to open it. The dart 73 therefore functions to ensure that the dump bailer 1 has the correct position and orientation within the lubricator assembly 51 for filling the dump bailer 1. The lubricator assembly 51 also comprises a wash line inlet 75 and wash line outlet 77 for washing the lower portion of the dump bailer 1 with a cleaning liquid. The inclined surface of the guide 67 is configured to guide the cleaning liquid out of the wash line outlet 77 to ensure that all residues from the cleaning process are removed from the lubricator assembly 51.

[0077] FIGS. 5a and b show a cross sectional view of a portion of the dump bailer 1 as it is being filled with flowable material in the lubricator assembly 51 as in FIG. 4b. The filling valve 17 is held open by the dart 73 to allow the flowable materials to be injected through the filling valve 17 via the inlet 71 of the lubricator assembly 51. The seal cup 72 seals against the surroundings so to prevent flowable material contaminating the lubricator assembly 51, or wellbore fluid form the lubricator assembly 51 contaminating the flowable material. During filling the wiper plug 25 is displaced upwards with the main chamber 23 as the lower chamber 29 is filled with flowable material. As the first tensioned valve system 31 (see FIG. 2) is in passive position, liquid from the upper chamber 27 exits to the surroundings via the port 19. In FIG. 5a, the second tensioned valve system 33 will be closed during the filling process due to the spring force of the second spring 43 being much higher than the force resulting from the injection pressure of the flowable material. In FIG. 5b, the second tensioned valve system 33 comprises a locking mechanism for locking the second tensioned valve system 33 in closed position during filling of the dump bailer 1. More specifically, the locking mechanism in FIG. 5b includes a first pin 76 extending from the filling valve 17 towards the port 45 for liquid communication between the lower chamber 29 and the outlet 15, wherein the first pin 76 engages a cap 78 on a second pin 80 connected to the second valve member 41 when the filling valve 17 is opened. The engagement of the first pin 76 with the cap 78 thereby prevents the second valve member 41 from being displaced downward and allowing liquid communication between the lower chamber 29 and the outlet 15 through the port 45 while the filling valve 17 is open. If such a locking mechanism is used, the second tensioned valve system 33 may be required to withstand a smaller pressure than it would have been required to without the locking mechanism, which therefore puts less requirements on the second tensioned valve system 33 and the second spring 43.

[0078] FIGS. 6a-d show a method for depositing a cement plug 79 on a retainer 81 in a wellbore using the dump bailer 1. Initially, the dump bailer 1 is lowered into the wellbore to the position of the retainer 81 (FIG. 6a). A depth-measuring tool 5 keeps ensures that the correct depth is reached. A small portion of the cement slurry is deposited on the retainer 81 until the cement plug 79 covers the outlet 15 of the dump bailer 1 (FIG. 6b). As the dump bailer 1 has complete control of rate of deposition of cement slurry and position of the dump bailer 1, the dump bailer 1 is withdrawn upwards with the same speed as the deposition rate, whereby the outlet 15 of the dump bailer 1 stays immersed in the cement plug 79 during the deposition process (FIGS. 6c and d). After the first round, the dump bailer is withdrawn to the surface (FIG. 6e) and refilled, and then lowered into the wellbore again to continue the deposition process. When using the lubricator assembly according to the invention, the refilling process is sufficiently fast so that the cement plug 79 does not cure during the refilling of the dump bailer 1. Therefore, when the dump bailer 1 returns to the cement plug 79, the dump bailer 1 can be immersed into the cement plug 79 again (FIG. 6f) so that the outlet 15 is below the surface, and the process of withdrawal during deposition can continue (FIG. 6g). The method of deposition shown in FIG. 6 provides a cement plug 79 with a high quality. For example, since the cement plug 79 does not have time to cure between subsequent rounds, there will not be any weak intern faces due to different times of curing between the cement slurry deposited in different rounds. Additionally, since the outlet 15 of the dump bailer 1 is immersed below the surface of the cement plug 79 during deposition of cement slurry, there will not be mixed any contaminants from the wellbore fluid into to the cement plug 79 during deposition. The result of the deposition is therefore a homogenous cement plug 79 without weak interfaces or contamination.

[0079] A typical operation for plugging a wellbore with a cement plug may be: [0080] Rigging up all pressure control equipment on the well, including the lubricator assembly 51. [0081] Place the tool string with the dump bailer 1 in the lubricator assembly 51 and pressure test according to procedure. [0082] If pressure test is ok, equalize the pressure over the valve against the wellbore. [0083] Engage the guide 67 for providing the dump bailer 1 with the correct orientation, and land and orient dump bailer 1. [0084] Open filing valve 17 with dart 73 and operate seal cup 72 to seal around filling valve 17 in dump bailer 1. [0085] Test the connection by bleeding off pressure in the inlet 71 of the lubricator assembly 51 while the wiper plug 25 is in bottom position. The pressure will immediately drop to 0 if sealing is ok. This shows that the wiper plug 25 is sealed, the seal cup seals properly, and the second tensioned valve system of the dump bailer 1 is sealed. [0086] Fill the dump bailer 1 with cement slurry to maximum capacity. The filling pressure is kept below the opening pressure of the second tensioned valve system 33 to prevent leakage in the lubricator assembly 51. Cement slurry will displace the liquid content above the wiper plug 25 and push it out of the upper chamber 27 through the first tensioned valve system 31 of the dump bailer 1. As it is important to maintain the pressure in the lubricator assembly 51, this is done by regulating a bleeding pressure when the cement slurry is filled into the dump bailer 1. [0087] When filling is completed, the filling valve 17 is closed by pulling out the dart 73. Cement slurry is now placed in the dump bailer 1 without exposure to equipment and personnel. The passive position of the tensioned valves of the dump bailer 1 holds the cement slurry in the lower chamber 29 of the dump bailer 1. [0088] The status of the valves in the dump bailer 1 is checked before displacing the guide 67, by starting the pump 9 of dump bailer 1, thereby pressing lightly against the wiper plug 25 which is now in the upper part of the main chamber 23. Press against wiper plug 25 pressurizes the cement slurry in the lower chamber 29. If pressure is kept below the opening pressure of the second tensioned valve system 33, the system should be completely sealed. [0089] If the test is passed, the tool string is ready. [0090] Before displacing the guide 67, the wash lines inlet 75 and outlet 77 are opened for simple cleaning in case there has been any unintentional spillage of cement within the lubricator assembly 51. [0091] When the dump bailer 1 is to be refilled, this is performed using the same setup. [0092] If there is a desire to clean the inside of the dump bailer 1, this can also be done in the system. Then the dump bailer 1 is filled with a cleaning fluid pumped into the dump bailer 1 through the lubricator assembly 51. When the lower chamber 29 is filled with cleaning fluid, the pump 9 is started to wash out residues that may exist in valves etc. This can be repeated up to several times. Use of acid to weaken and remove old cement slurry is also possible without exposing operators to danger. The acid wears away any residual cement slurry and can help to get the dump bailer 1 back to operational condition quickly and efficiently. If the operation progresses smoothly and a round trip takes a short time, fresh cement slurry may be sufficient to keep the dump bailer 1 operational.

[0093] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb “comprise” and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article “a” or “an” preceding an element does not exclude the presence of a plurality of such elements.

[0094] The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.