Process for isolating a horizontal tie-in pipeline of an inactive hydrocarbon-producing well from a main pipeline

Abstract

A method for isolating a horizontal tie-in pipeline of an inactive hydrocarbon-producing well from a main pipeline to prevent flow of hydrocarbons into the tie-in pipeline includes the steps of: identifying a location of a junction of the tie-in pipeline and the main pipeline and cleaning the tie-in pipeline by deploying a locating and cleaning assembly into the tie-in pipeline, withdrawing the locating and cleaning assembly, deploying a plug device having a longitudinally extending forward probe and a sealing element to the location of the junction, and remotely actuating the sealing element. The locating and cleaning device includes a pipeline junction sensing element longitudinally extending from a forward end of the locating and cleaning device. The sensing element is connected to a valve which, when open, relieves pressure in the locating and cleaning assembly as an indicator of the location of the junction.

Claims

1. A method for isolating a horizontal tie-in pipeline of an inactive hydrocarbon-producing well from a main pipeline to prevent flow of hydrocarbons into the tie-in pipeline, the method comprising: a) identifying a location of a junction of the tie-in pipeline and the main pipeline and cleaning the tie-in pipeline by deploying a locating and cleaning assembly into the tie-in pipeline, the locating and cleaning assembly including a pipeline junction sensing element longitudinally extending from a forward end of the locating and cleaning assembly, the sensing element connected to a valve which, when open, relieves pressure in the locating and cleaning assembly as an indicator of the location of the junction; b) withdrawing the locating and cleaning assembly; c) deploying a plug device having a longitudinally extending forward probe and a sealing element to the location of the junction; and d) remotely actuating the sealing element.

2. The method of claim 1, wherein the probe is dissolvable in hydrocarbons.

3. The method of claim 1, wherein the locating and cleaning assembly further includes a radio transmitter to indicate or confirm the location of the junction.

4. The method of claim 1, wherein the locating and cleaning assembly includes one or more ports adjacent to the sensing element, for exit of pressurized gas to clean the locating and cleaning assembly and the tie-in pipeline.

5. The method of claim 1, wherein the locating and cleaning assembly is deployed to the junction using coiled tubing.

6. The method of claim 5, wherein the pressure in the locating and cleaning assembly is sensed at surface via the coiled tubing.

7. The method of claim 1, wherein the sealing element is configured to be deactivated and the plug is configured to be retrieved to reactivate the tie-in pipeline.

8. The method of claim 1, further comprising the step of pumping liquid or gas out of the tie-in pipeline after the step of remotely actuating the sealing element.

9. The method of claim 8, further comprising pumping preservative liquid or gas into the tie-in pipeline.

10. The method of claim 1, wherein the pipeline junction sensing element is connected to a separate cleaning component using a swivel connector.

11. The method of claim 10, wherein the separate cleaning component includes a radio transmitter to indicate or confirm the location of the junction.

12. The method of claim 10, wherein the separate cleaning component is configured for connection to coiled tubing using a second swivel connector.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Various objects, features and advantages of the disclosed technology will be apparent from the following description of particular embodiments, as illustrated in the accompanying drawings. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of various embodiments of the technology. Similar reference numerals indicate similar components.

(2) FIG. 1 is a schematic illustration of a well installation 10 which has a tie-in line 22 extending from the injection station 20 to a main pipeline 26.

(3) FIG. 2A is a schematic illustration of an arbitrary longitudinal cross-section of a T-junction 224 for joining a tie-in line 222 to a main pipeline 226.

(4) FIG. 2B is a schematic illustration of an arbitrary longitudinal cross-section of a Y-junction 324 for joining a tie-in line 322 to a main pipeline 326.

(5) FIG. 3 is a side elevation view of one embodiment of a bridge plug 400.

(6) FIG. 4 is a partial side view of the bridge plug 400 of FIG. 3 inside a tie-in line 322.

(7) FIG. 5 is a partial side view of the bridge plug 400 arriving at a Y-junction 324 showing extension of one of the biased fins 404.

(8) FIG. 6 is a side elevation view of another embodiment of a bridge plug 500.

(9) FIG. 7 is a partial side view of the bridge plug 500 of FIG. 6 inside a tie-in line 322.

(10) FIG. 8 is a partial side view of the bridge plug 500 arriving at a Y-junction 324.

(11) FIG. 9 a partial side view of a locating and cleaning assembly 600 with inset A indicating detail of the junction locator sub 610.

(12) FIG. 10 is a schematic illustration of detection of the location of the locating and cleaning assembly 600 by the locator 640 at the point when the probe 611 reaches the opposite wall of the main pipeline 326.

(13) FIG. 11A is a side view of a T-junction 224 with the forward end of the junction locator sub 610 of the locating and cleaning assembly 600 in the tie-in line 222 prior to contact of the probe 611 with the opposite wall of the main pipeline 226. The ball valve 612 is closed.

(14) FIG. 11B is a side view of a T-junction 224 with the forward end of the junction locator sub 610 in the tie-in line 222 with the probe 611 in contact with the opposite wall of the main pipeline 226 triggering opening of the ball valve 612.

(15) FIG. 12A is a side view of a Y-junction 324 with the forward end of the junction locator sub 610 in the tie-in line 322 prior to contact of the probe 611 with the opposite wall of the main pipeline 326. The ball valve 612 is closed.

(16) FIG. 12B is a side view of a Y-junction 324 with the forward end of the junction locator sub 610 in the tie-in line 322 with the probe 611 in contact with the opposite wall of the main pipeline 326 triggering opening of the ball valve 612.

DETAILED DESCRIPTION

(17) Rationale and Advantages

(18) Underground tie-in branch lines of inactive hydrocarbon-producing wells are most often not properly suspended in accordance with regulations as this requires excavation of the tie-in and subsequent treatment of the inactive pipeline. However, if the pipeline tie-ins are not properly suspended and no flow occurs through them, there is an increased probability that corrosive fluids will accumulate inside the pipeline and such an occurrence can cause a pipeline failure.

(19) Historically, underground tie-ins are not suspended in accordance with regulations and the risk of pipeline failure is accepted by the owner of the suspended well. If the owner decides to comply with regulations, the pipeline connection is excavated and the inactive line is properly abandoned. Currently, in view of the negative media reports of pipeline spills, further pressure is placed on regulators to bring violators into compliance with existing regulations relating to inactive pipelines.

(20) The inventor has discovered a solution to this problem which avoids the costly process of excavation, and the time associated with garnering appropriate approvals for excavation. The solution includes the use of a combination of technologies in a process for properly suspending an inactive section of a pipeline to bring it into compliance with regulations. In this process, a retrievable and remotely activatable plug is conveyed to the tie-in junction with the main pipeline, using coil tubing. The plug is provided with a mechanism for locating or confirming the location of the tie-in junction. The plug is sealed against the walls of the pipeline tie-in with a sealing element such as a hydraulically activatable packer element which is remotely activated. The plug may be unsealed and retrieved later if re-activation of the pipeline is desired. This operation is performed at the access point of the tie-in portion of the well, near the well itself. As such, there is no need to excavate any land above the location of the tie-in joint.

(21) This process provides a number of significant advantages to the owner of the pipeline tie-in. As noted above, no excavation is required because operations are conducted from the wellhead site. This prevents significant damage to cropland in situations where a pipeline to be suspended is located in an agricultural area as well as negating the possibility of incidental damage to other pipelines which may be present in the area. Negotiations with land owners for access to the tie-in connection site are not required, nor are crossing and proximity agreements from other industries nearby. These advantages provide significant savings in terms of time and expense and greatly lessen the risk of performing a suspension operation in accordance with regulations.

(22) Various aspects of the technology will now be described with reference to the figures. For the purposes of illustration, components depicted in the figures are not necessarily drawn to scale. Instead, emphasis is placed on highlighting the various contributions of the components to the functionality of various aspects of the technology. A number of possible alternative features are introduced during the course of this description. It is to be understood that, according to the knowledge and judgment of persons skilled in the art, such alternative features may be substituted in various combinations to arrive at different embodiments of the technology. Similar reference numerals are used to indicate similar components appearing in different embodiments, wherever possible.

(23) Description of a Process and Device for Installation of a Retrievable Bridge Plug in a Tie-In

(24) To facilitate an understanding of the disclosed technology, a typical hydrocarbon producing installation will first be described, followed by a description of different embodiments of a device and process for installation of a bridge plug for isolation of a tie-in line from a main pipeline to enable removal of hydrocarbons from the tie-in line. FIG. 1 is a schematic illustration of a hydrocarbon producing well installation 10 which includes a pump jack 12 for pumping hydrocarbons out from a production wellbore 14. The produced hydrocarbons exit the wellhead 16 via a production line 18 which extends to an injection station 20 to provide an entry point for the produced hydrocarbons to enter a tie-in line 22. The tie-in line 22 extends to a junction 24 with a main pipeline 26.

(25) FIGS. 2A and 2B illustrate two types of junctions. FIG. 2A illustrates a T-junction (or “tee-junction”) 224 formed by joining a tie-in line 222 to a main pipeline 226 at a substantially perpendicular angle. FIG. 2B illustrates a Y-junction (or “Wye-junction”) 324 formed by joining a tie-in line 322 to a main pipeline 326 at an angle which is not a substantially perpendicular angle (in this case, approximately a 45 degree angle).

(26) FIG. 3 illustrates a side view of one embodiment of a bridge plug 400 configured for use with embodiments of the process described herein for isolating fluid and/or gas flow from a tie-in line of a hydrocarbon-producing well from a main pipeline. This bridge plug 400 has a main body 401 which is connectable to coil tubing (not shown) for conveyance of the bridge plug 400 to the tie-in junction site (not shown). The bridge plug 400 has a pair of remotely activatable sealing elements 402 and 403 in the form of inflatable packers or other known sealing elements which are arranged circumferentially around the main body 401. These sealing elements 402 and 403 are remotely activatable. While two sealing elements 402 and 403 are shown in this example embodiment, it may be possible to provide only a single sealing element or more than two sealing elements in alternative embodiments. One variation which uses two sealing elements provides an articulating joint between the two sealing elements in order to allow the bridge plug to more efficiently traverse bends in the tie-in line (not shown).

(27) This embodiment of the bridge plug 400 includes a set of retractable fins 404 near its forward end which are biased to extend out of the body of the bridge plug 400. These biased fins 404 retract into the body of the bridge plug 400 with application of force against them. Therefore, as indicated in FIG. 4, while the bridge plug 400 is being conveyed by coil tubing into a tie-in line 322, the biased fins 404 are forced into the retracted position (inside the body of the bridge plug 400) as they encounter the inner sidewall of the tie-in line 322. It is seen in FIG. 5 that as soon as the forward end of the bridge plug 400 reaches the Y-junction 324, the top fin 404a has moved completely into the cavity of the main pipeline 326 and therefore extends out of the body of the bridge plug, depressuring the coil tubing and indicating the location of the junction 400.

(28) The bridge plug 400 is configured to detect the extension of the fins 404 by releasing pressure from the bridge plug 400 when extension of the fins 404 occurs. Typical pressure at the surface is illustrated in both FIG. 4 and FIG. 5 and it is seen that a pressure drop is detectable at the surface as soon as fin 404a is extended. This provides an indication that the bridge plug 400 has reached the Y-junction 324. At this point, outward conveyance of the bridge plug 400 is halted. The bridge plug 400 is then drawn back by a pre-determined distance to avoid having a significant portion of the head of the bridge plug 400 extending into the cavity of the main pipeline 324. When an appropriate position for the bridge plug 400 is reached (for example, with the forward sealable element 402 within about 6 inches of the tie-in junction 324 the fins 404 are retracted, causing pumping pressure to be re-established. The sealable elements 402 and 403 are then activated by a mechanism such as hydraulic pressure to seal the bridge plug 400 against the inner sidewall of the tie-in line 322. This isolates flow of hydrocarbons from the main pipeline 326 into the tie-in line 322. This process allows the well operator to properly suspend production of the well in accordance with regulations.

(29) Setting of the bridge plug 400 may be confirmed by a positive pressure test using inert fluid pumped into the tie-in line via the coil tubing. After the bridge plug 400 is set, it is released from the coil tubing and an inert fluid or gas such as nitrogen or water is used to purge the tie-in line 322 of corrosive fluid. The isolation of the tie-in line 322 from the main pipeline 326 by the bridge plug 400 is advantageously monitored with a surface pressure gauge located at an installation on the tie-in line at the original point of entry of the coil tubing.

(30) A second embodiment of a bridge plug 500 is shown in FIG. 6. This embodiment also has a pair of sealing elements 502 and 503 arranged circumferentially around the main body 501 of the bridge plug 500 which will operate in a generally similar manner as described for the bridge plug 400 of FIGS. 4 and 5. In this embodiment, the mechanism for determining or confirming the location of the tie-in junction is provided by an outwardly extending probe 506. FIG. 7 shows the bridge plug 500 at a point when it is traveling through tie-in line 322 and FIG. 8 shows the bridge plug 500 as it reaches the Y-junction 324. It is to be understood that with further forward conveyance of the bridge plug 500, the probe 506 will encounter the inner sidewall of the main pipeline 326. At this point, the probe 506 is used to correctly space the sealable elements from the tie in intersection. Then sealable elements 502 and 503 are activated to seal the bridge plug 500 against the inner sidewall of the tie-in line 322. This isolates flow of hydrocarbons from the main pipeline 326 into the tie-in line 322. This process allows the well operator to properly suspend production of the well in accordance with regulations.

(31) In one alternative embodiment of the bridge plug 500, the probe 506 is formed of a dissolvable material. This avoids the permanent presence of a probe extending into the main pipeline 326. The dissolvable probe may be formed of any material which is dissolvable in pipeline fluid at a suitable rate. This material may be selected on the basis of tests performed by a person having ordinary skill in the art which will not require undue experimentation.

(32) Locating and Cleaning Assembly

(33) Prior to suspension of operation of a tie-in line of a production well, it is desirable to clean the tie-in line to minimize the chances of corrosion occurring during the suspension period and improve the successful setting of the plug. The inventor has recognized that this cleaning step can be advantageously combined with an initial locating step to remotely determine the location of the tie-in junction prior to deployment of the bridge plug to isolate the tie-in line from the main pipeline. An example of a locating and cleaning assembly for performing the cleaning and locating tasks is shown in FIG. 9.

(34) This embodiment of the locating and cleaning assembly 600, includes a junction locator sub 610 which is shown in a magnified view in inset A in FIG. 9. The junction locator sub includes a forwardly extending probe 611 with a ball valve 612 at its rearward end. The ball valve 612 is in the closed position in a ball seat 613 when the assembly 600 is travelling through the tie-in line and the probe 611 is not encountering significant resistance. The function of the probe 611 and ball valve 612 will be described in more detail hereinbelow with respect to FIGS. 10-12.

(35) The junction locator sub 600 has a pair of forward cleaning ports 614a and 614b for exit of pressurized gas which acts to clean the assembly itself as well as the interior of the pipeline. The junction locator sub 610 is provided with a swivel connector 620 for connection to a pipeline cleaning component which is known in the art as a “cleaning pig.” The cleaning pig 630 forms an intermediate portion of the assembly 600. In this particular embodiment, the cleaning pig 630 has a locator 640 attached thereto. The locator 640 may be a pipeline logging transmitter or sonde which generates signals detectable by a radio receiver R at the surface as shown in FIG. 10. The cleaning pig 630 is connected to the coil tubing 650 used for conveyance of the assembly 600 via a swivel connector 651. While the locator 640 is shown in association with the cleaning pig 630, it may be possible to attach the locator 640 to a different component of the assembly 600, such as the junction locator sub 610, for example.

(36) FIG. 10 provides an illustration of how the locating and cleaning assembly detects the location of the junction of a tie-in line 322 with the main pipeline 326 (shown in transverse cross section. When the probe 611 encounters the inner sidewall of the main pipeline 326, the ball valve 612 is forced to move away from its seat 613 and thus releasing pressure from the assembly. This pressure drop is detected at the surface and triggers a signal to be transmitted by the locator 640 to identify the location of the tie-in junction 324.

(37) FIGS. 11 and 12 illustrate the action of the ball valve 612 at a T-junction 224 and at a Y-junction 324, respectively. It is seen in both cases that a pressure drop is detected at the surface when the probe 610 encounters the inner sidewall of the main pipeline 226 of the T-junction 224 (FIG. 11B) and the main pipeline 326 for the Y-junction 324.

(38) Example 1: Locating, Cleaning and Isolation of a Tie-In Line During Suspension of a Pipeline

(39) An example process for preparing a tie-in line for suspension will now be described. With the decision to suspend production of a producing well, the flow of hydrocarbons to the wellhead is stopped. Then a locating and cleaning assembly such as the assembly 600 of FIG. 9 is attached to the forward end of a spool of coil tubing and conveyed into the tie-in line. It is possible in some cases that partial excavation of the tie-in at the point of entry will be required to improve its configuration for entry of the assembly and coil tubing, particularly if there is a significant bend of the tie-in line at the desired entry point.

(40) When appropriate entry of the cleaning and locating assembly into the tie-in line is established, this assembly is conveyed through the tie-in line to clean hydrocarbons and deposits from the tie-in line. When the probe of the assembly reaches the inner sidewall of the main pipeline, a sensor detects this contact and as a result, there is a pressure release in the assembly which is detected at the surface. At this point, the locator transmits a signal to indicate that the tie-in junction has been reached. This provides a first indication of the location of the tie-in junction. The locating and cleaning assembly is then withdrawn from the tie-in line.

(41) In a subsequent step, a retrievable bridge plug with a mechanism for locating the tie-in junction is conveyed to the tie-in junction using coil tubing. When the mechanism for locating the tie-in junction is triggered, the sealing elements of the bridge plug are remotely activated to isolate the tie-in line from the main pipeline, thereby preventing entry of hydrocarbons into the tie-in line. This system provides two independent determinations of the location of the junction, providing increased confidence that the location of the junction has been correctly determined.

(42) Equivalents and Scope

(43) The terms “one,” “a,” or “an” as used herein are intended to include “at least one” or “one or more,” unless otherwise indicated.

(44) Any patent, publication, internet site, or other disclosure material, in whole or in part, that is said to be incorporated by reference herein is incorporated herein only to the extent that the incorporated material does not conflict with existing definitions, statements, or other disclosure material set forth in this disclosure. As such, and to the extent necessary, the disclosure as explicitly set forth herein supersedes any conflicting material incorporated herein by reference. Any material, or portion thereof, that is said to be incorporated by reference herein, but which conflicts with existing definitions, statements, or other disclosure material set forth herein will only be incorporated to the extent that no conflict arises between that incorporated material and the existing disclosure material.

(45) Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this technology belongs.

(46) While this technology has been particularly shown and described with references to embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the disclosure encompassed by the appended claims.