GB2568224A - A method of monitoring fluid flow and fluid position behind conductor, casing or tubing during wellbore clean up and/or abandonment operations - Google Patents

Abstract

Disclosed is a method of monitoring flowing or static fluid and simulating a fluid 10 in an oil or gas well. Tracking devices or location tags 11 such as nano chips, pip, PIT or RFID tags are suspended or mixed within a fluid which is then displaced down a well. A detector or a series of detectors mounted on a work string or similar is able to read the signals of the tracking devices. Computer software will decode the signals to show their real-time location in the wellbore. The method may use the fluid for wellbore clean-up or abandonment operations. An additive such as a gel, cellulose fiber, viscosified fluid or cement may be added to the fluid to increase the carrying capacity of the fluid.

Description

F!ELD OF THE !NVENT!ON

The invention comprises a method of monitoring a flowing or static fluid which may be but not limited to a multi-mixture oil/gas/chemicai/cement/water mixture flowing or static behind a conduit that can include but not limited to conductor, casing or tubing typically found in an oil or gas well. The method comprises adding tracking devices such as but not limited to nano chip, pip, PIT (Passive Integrated Transponder) or RFID (Radio Frequency Identification) tags to the flowing or static fluid. The movement, flow or final static position of the fluid containing the nano chip. pip. PIT or RFID tags can be detected by using one or more detectors in close proximity to the area required to be monitored.

BACKGROUND OF THE INVENTION

As oil and gas wells become no longer economically viable for production, or which have wellbore issues that require closure, the wellbore has to be plugged and abandoned (P&A). Production wells that can no longer be used must be plugged to prevent the oil and gas reservoir fluids from migrating uphole over time and possibly contaminating other formations and or fresh water aquifers. A well is plugged by setting mechanical or cement plugs in the wellbore at specific intervals to prevent fluid flow.

As part of the regulations surrounding the individual cement plugs set at different intervals in the well, consideration also needs to be given to the cement bond behind the conduit of pipe being filled with the cement plug. If there is insufficient support or cement behind the conduit wall there is potential for oil or gas to migrate behind casing and find its way to the surface or aquifers causing untold environmental effects.

Logging tools can be run into the wellbore to detect and analyse the cement bond behind the casing wall. When the cement bond behind the casing wall is deemed to be insufficient, remedial cement work is required and one such method is to perforate holes in the casing to gain access to the annulus area between strings of casings. Typically holes will be perforated at the bottom and the top of the casing within the area of the insufficient cement bond.

Before remedial cement is injected or flowed into the area behind the casing, it is important that the annulus area is clean and free from fluids such as drilling muds and oil based mud as well as debris and contaminants to provide a good clean (water wet) base for cement to bond. Wellbore clean up tools run into the well typically on drill pipe can direct and flow fluids with or without cleaning additives into these areas. One such issue with the current method is it is difficult to determine when and what area is being cleaned.

Therefore, there is an opportunity to design a method of accurately measuring and quantifying the fluid flow being injected or pumped into the wellbore and into annular areas. By adding multiple nano chip, pip, PIT or RFID tags to the injected or pumped cleaning fluids at surface it will be possible to create, using a series of detectors and readers, a real-time flow analysis of the fluid in the annulus area or any other area requiring monitoring in the wellbore. This flow analysis can be used to determine when the area is adequately cleaned and the remedial cement job can take place to isolate and seal off permanently behind the casing. The addition of the nano chip, pip, PIT or RFID tags will allow the path and position of the fluid to be known. The fluid can be but not limited to one or multi5 mixture oil/ gas/ chemical/ cement/ water. Additionally, the fluid can be flowing or static in the well.

Using the nano chip, pip, PIT or RFID tags, the final/settled position of the fluid can be correlated to determine if the fluid is evenly spread in the monitored area.

The invention can also be used when different fluids are injected into a well to monitor where each fluid is in the well or each fluid relative to each other, this can be carried out by using nano chip, pip,

PIT or RFID tags with individual detection signals.

The invention can also be used when a one of or a multi-mixture oil/gas/chemical/cement/water becomes static in a well, this can be carried out by using nano chip, pip, PIT or RFID tags to determine the final position and correlate if the fluid or multi mixture oil/gas/chemical/cement/water is evenly spread in the monitored area.

SUMMARY OF THE INVENTION

According to the present invention there is provided a method to monitor and record fluid flowing or static in a wellbore or behind a string or strings of conduits typically casings or tubing used in oil and gas wells comprising:

A quantity of nano chip, pip tags, PIT tags or RFID tags or similar mixed with fluid being injected or pumped into the wellbore;

A quantity of nano chip, pip tags, PIT tags or RFID tags or similar, all with different or the same monitoring signature mixed with fluid being injected or pumped into the wellbore;

A series of monitoring or detecting devices mounted on the drill string or a handheld intrinsically safe or otherwise device used at surface or in an area on the rig;

A computer software to collect and analyze data from monitoring or detecting devices.

Optionally, the concentration of nano chip, pip, PIT or RFID tags (from herein will be described as location tags) can be adjusted to suit the clean-up operations without impacting on the cleaning ability of the fluid. A higher concentration of location tags will allow a more accurate representation of the fluid and its location.

Optionally, the location tags are sized small enough to prevent disturbing the cleaning ability of the fluid. Optionally, the location tags are nano-sized. Optionally, the location tags are encapsulated or inert and do not react with fluids being injected or already in the wellbore. Optionally, if required, the location tags can be large enough to be recovered at surface. Optionally, the location tags can be reused. Optionally, the location tags will not interfere with the ability for the cement to bond or harden.

Optionally, the fluid being injected into the wellbore has a carrying capacity equal to or greater than the location tags. The fluid can be but not limited to water, water-based mud, oil, oil-based mud, cleaning fluids, surfactants or similar fluids commonly injected into the wellbore. Optionally, if the carrying capacity of the fluid is insufficient, additives may be added. This can be but not limited to viscosifiers, gelling agents, cellulous fibers etc. Optionally, the carrying ability of the fluid is able to carry the location tags down the wellbore as well as suspending and removing any debris in the wellbore and bringing them to surface. This is especially important in wellbore clean up applications.

Optionally, the fluid can be static. Optionally, the location tags can be mixed into a cement slurry or similar for abandonment applications. Once the cement slurry or similar and location tags have entered the wellbore and into the required location behind or inside the casing, the monitoring or detecting devices can determine if the cement slurry or similar has been evenly distributed. Optionally, if the location tags show an even distribution behind the casing, there is no requirement for a cement bond log (CBL) to take place therefore saving time and money.

Optionally, the location tags can be injected into the wellbore at different stages. Optionally, the location tags at each stage will inherit a different signal from the previous. Optionally, each stage can contain a different fluid. Optionally, this will be suited for wellbore clean up applications. Optionally, monitoring or detecting devices at surface will be able to observe the returns, therefore determining which and where the fluids are in the wellbore.

Optionally, the monitoring or detecting devices are mounted on the work string. The monitoring or detecting devices can be positioned at intervals on the work string which allow for full detection coverage ensuring no dead-spots. The monitoring or detecting devices can be mounted at intervals longitudinally and radially on the work string to achieve full capture of the location tags. Optionally, the monitoring or detecting devices may be powered by batteries housed within the units or supplied by surface via control line or similar. Optionally, handheld or fixed devices at surface can monitor the fluid. Optionally if the location tags are launched in stages, the monitoring or detecting device at surface can in real-time display which stage of fluid and location tags are currently returning from the wellbore. Optionally, the monitoring or detecting devices are able to transmit data back to surface using radio waves. Optionally, the monitoring or detecting devices are able to detect the location tags behind casing or tubulars. Optionally, the monitoring or detecting devices emit and receive signals strong enough to penetrate metallic casings or tubulars.

Optionally, a computer software/program will collect the data from the detecting or monitoring devices and collate into a real-time simulation. Optionally, the computer software/program is able to plot a 2D or 3D visual representation of the location tags. Optionally, the computer software/program is able to determine the velocity of the location tags. Optionally, the velocity of the location tags can be graded against a colour scale. For example, a fast moving location tag can be green but a static location tag can be red. Optionally, velocities in-between can be assigned another colour. Optionally, the simulation can show areas of turbulent flow.

The various aspects of the present invention can be practiced alone or in combination with one or more of the other aspects, as will be appreciated by those skilled in the relevant arts. The various aspects of the invention can optionally be provided in combination with one or more of the optional features of the other aspects of the invention. Also, optional features described in relation to one example can optionally be combined alone or together with other features in different examples of the invention.

Various examples and aspects of the invention will now be described in detail with reference to the accompanying Figures. Still other aspects, features and advantages of the present invention are readily apparent from the entire description thereof, including the Figures, which illustrate a number of exemplary aspects and implementations. The invention is also capable of other and different aspects and implementations, and its several details can be modified in various aspects, all without departing from the spirit and scope of the present invention. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be constructed as limiting in scope.

Language such as including, comprising, having, containing, or involving, and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term comprising is considered synonymous with the terms 5 including or containing for applicable legal purposes.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example only and not in any limitative sense, with reference to the accompanying drawings, in which:

Figure 1 is a sectioned view of a wellbore with the casing perforated above and below an area deemed to have an insufficient cement bond;

Figure 2 is a sectioned view of a wellbore showing an obstruction/ debris behind the casing;

Figure 3 is a sectioned view of a wellbore with the casing perforated above and below and fluid exiting an open ended pipe with the location tags;

Figure 4 is a sectioned view of a wellbore and annulus where the fluid has cleaned the debris and left a satisfactory flow pattern behind the conduit;

Figure 5 is a schematic view of a typical shaker system on a rig and monitoring or detecting device analysing the fluid returned to surface;

Figure 6a and Figure 6b are schematic views of possible read-out displays from the monitoring or 15 detecting device;

Figure? is a schematic view of the computer software/program display showing a real-time simulation of the fluid position and velocity in relation to the wellbore.

DETAILED DESCRIPTION OF THE DRAWINGS

Figure 1 shows a sectioned schematic view of a possible arrangement of a wellbore 100. The inner casing 1 is fixed to the outer casing 3 by cement 2 in the annulus area 6. Upper 4 and lower 5 perforations or holes have been made into the casing 1 to allow fluid access to the annulus 6 where the cement bond is poor. The plug or packer 7 is set below the lower perforation 5 to isolate the zones below the plug or packer 7.

Figure 2 shows a sectioned schematic view of a possible arrangement of a wellbore 100. As per Figure 1, the wellbore contains a set of upper 4 and lower 5 perforations, however there is presence of an obstruction 8 behind the casing annulus 6. The obstruction 8 can be but not limited to oil based mud, cement sheaths or casing particles from the perforating operation. Typically to ensure the annulus 6 is free from debris, fluid is injected into the wellbore 100 and directed into the perforations 4, 5. This provides the optimum condition in the annulus 6 prior to placing plugging material.

Figure 3 shows a sectioned schematic view of a possible arrangement of a wellbore 100. The work string 9 is positioned above the plug or packer 7 and in the area of the casing that has been perforated. Fluid 10 is directed down through the work string 9 and out the open-ended bottom of the work string

9. The fluid 10 can contain cleaning agents or similar to enhance the cleaning ability. The fluid 10 also contains location tags 11. The fluid 10 is circulated in and around the annulus 6 behind the casing before circulated back to surface. The carrying capacity of the fluid 10 is sufficient enough to carry both the location tags 11 and also any debris in the annulus (for example 8). Monitoring devices 12 mounted on the work string 9 track the location and velocity of the location tags 11 before feeding the signal back to surface. A number of monitoring devices 12 can be positioned on the work string 9 to allow for full 360 degree coverage of the wellbore 100.

Figure 4 shows a sectioned schematic view of a possible arrangement of a wellbore 100. The fluid 10 has dislodged and carried the obstruction 8 in the annulus 6 back to surface. The location tags 11 can verify that the annulus 6 is clean and free from debris as they are now evenly spread in the annulus 6. Optionally, the location tags 11 can be mixed into a fluid which will be used to abandon or seal the annular area 6. Such fluid can be but not limited to cement. An even spread of fluid (cement) can verify that a good cement bond can be achieved. The location tags 11 used in such scenarios must not interfere with the cement bond between inner casing 1 and outer casing 3 or affect hardening of the cement.

Figure 5 shows a schematic view of the shakers 13 on the rig floor (surface). A handheld or portable monitoring or detecting device 14 is shown as mounted on a frame 15 near the shakers 13. As the fluid 10 returns to surface, the location tags are picked up by the monitoring or detecting device 14. Optionally, an operator can use the device 14 rather than being mounted on a frame 15. A display screen 16 shows in real time the location tags coming back to surface. Preferably, this scenario is used when different fluids are injected into the wellbore with different location tags. The return of each fluid can be tracked at each stage showing that any fluid entering the well has also returned to surface.

Figure 6a shows a schematic view of a possible reading from the display screen 16 of the handheld or portable monitoring or detecting device 14. Each graph 17 shows the return of a group of location tags in real-time, for example three different fluids. The graph can show quantity vs time or any other variables. As time passes, the quantity of stage 1 tags returned to surface will be nearly or exactly the same as it was when injected or pumped into the wellbore. It is expected that all/majority of stage one location tags would return to surface before stage two is detected and so forth.

Figure 6b shows a schematic view of a possible reading from the display screen 16 of the handheld or portable monitoring device 14. In this embodiment, there is only one type of location tags used in one type of fluid.

Figure 7 shows a schematic view of a possible display arrangement of the computer software used.

The arrangement of monitoring devices on the work string collecting the location and velocity of the location tags are analysed and an output is generated in a user-friendly interface. A simulated visual representation of the wellbore 18 is shown. The position of the location tags 11 are shown in realtime flowing in and around the annulus area 6. Optionally, the number of tags are not limited as long as each signal is unique and can be picked up by the monitoring or detecting devices. The location tags 10 11 can be assigned a colour depending on the relative velocities. A fast flowing location tag would have a different colour from a slow moving one. This provides the advantage of an easy to read overview of the wellbore. Slow moving location tags would indicate debris obstruction or similar. Once all tags show high moving velocities, it is predicted that the wellbore is clean and free from debris. More than one type of location tags 11 can be detected and displayed by assigning different symbols 15 19 to each.

Further modification and improvements may be incorporated or made to the embodiments hereinbefore described without departing from the scope of the invention as defined in the claims.

Claims (17)

1. A method of using location tags such as but not limited to nano chip, pip, PIT or RFID tags and one or more detecting or monitoring devices to analyse and produce a real-time simulation of fluid movement and position comprising:

A quantity of nano chip, pip, PIT or RFID tags (location tags) or similar suspended, mixed and/or carried in a fluid,

An arrangement of monitoring or detection devices to track the position and velocity of the nano chip, pip, PIT or RFID tags (location tags) or similar in the wellbore and at surface,

A computer program/software to collate and analyse the data gathered from the monitoring or detection devices.

2. A method as claimed in claim 1, including using a fluid for wellbore clean up (WBCU) or abandonment applications.

3. A method as claimed in claim 1 or claim 2, including using a fluid which has a carrying capacity equal to or greater than the location tags.

4. A method as claimed in any one of claims 1-3, including using an additive if the carrying capacity of the fluid is insufficient.

5. A method as claimed in claim 4, including using but not limited to gels, cellulose fibers, viscosified fluid or cement.

6. A method as claimed in any one of claims 1-5, including using fluids which contain cleaning agents, solvent surfactants and gelling agents but not limited to.

7. A method as claimed in any one of claims 1-6, including the fluid being dynamic or static and being returned to surface or remaining in the wellbore.

8. A method as claimed in any one of claims 1-7, including injecting or pumping a number of different fluids in the wellbore where the location tags can be loaded in stages.

9. A method as claimed in claim 8, including the location tags emitting a different signal or containing unique data or unique monitoring characteristics at different stages.

10. A method as claimed in claim 1, including using the location tags in abandonment applications by mixing with cement or similar removing the need for cement bond logging tools.

11. A method as claimed in claim 1, including a series of monitoring or detecting devices mounted longitudinally and radially around the work string.

12. A method as claimed in claim 11, including using radio waves or electrical signals or similar to send and receive data from location tags strong enough to capture areas behind one or more conduits of pipe/casing.

13. A method as claimed in claim 11 and claim 12, including arranging the monitoring or detecting devices in a way where 360 degree capture area is created with minimal or no dead spots.

14. A method as claimed in claim 1, claim 9 and claim 12, including using a handheld or fixed monitoring or detection device to determine in real time when each fluid is returned to surface (typically in the shaker house).

15. A method as claimed in any one of claims 1-14, including using a computer program or software to plot a real time diagram/graph of fluid movement in areas behind one or more conduits of pipe/casing.

16. A method as claimed in claim 15, including using a computer program or software to determine areas of turbulent flow in the wellbore.

17. A method as claimed in claim 15, including using colour representation to establish areas of fast or slow moving fluid being monitored.