NO20160181A1

NO20160181A1 - Apparatus and method for monitoring conditions in a defined volume in a borehole

Info

Publication number: NO20160181A1
Application number: NO20160181A
Authority: NO
Inventors: Kåre Olav Krogenes; Jan Erik Skjold
Original assignee: Ind Controls As
Priority date: 2016-02-03
Filing date: 2016-02-03
Publication date: 2017-08-04
Also published as: GB201812532D0; WO2017135827A1; NO342104B1; GB2562421A; GB2562421B

Abstract

Apparatus (1) for monitoring conditions in a defined volume (V) in a borehole, the defined volume (V) containing one or more borehole fluids, the apparatus (1) comprising a reservoir (6) for storing a boundary fluid, the apparatus further comprising at least one energy source and means for communication, wherein the apparatus (1) is adapted to release the boundary fluid into the defined volume (V) and the apparatus (1) comprises one or more means of detecting fluid characteristics (51-510), wherein the means of detecting fluid characteristics (51-510) are arranged to monitor said fluid characteristics in a portion of the defined volume (V). Method for monitoring conditions in a defined volume in a borehole by means of an apparatus (1) according to claim 1, wherein the method comprises the release of a boundary fluid into the defined volume (V) and the subsequent detection of fluid characteristics in a portion of the defined volume Apparatus (1) for monitoring conditions in a defined volume (V) in a borehole, the defined volume (V).

Description

APPARATUS AND METHOD FOR MONITORING CONDITIONS IN A DEFINED VOLUME IN A BOREHOLE

The invention re lates to an apparatus for monitoring conditions in a defined volume in a borehole. The apparatus is adapted to release a boundary fluid into said volume, and through the use of means of detecting fluid characteristics to monitor fluids present in a part of said volume.

Gathering fluid characteristics data from a well can be of vital importance. Such information can be used to gain an understanding of the downhole conditions, such as whetherthere is a build-up of gas below a valve, if a valve or plug is leaking, or other safety critical information.

The invention is defined by the independent patent claims. The dependent claims define advantageous embodiments of the invention.

In a first aspect the invention relates to an apparatus for monitoring conditions in a defined volume in a borehole. The defined volume contains one or more borehole fluids. The apparatus comprises a reservoir for storing a boundary fluid, at least one energy source, and means for signal communication. The apparatus ischaracterised in thatit is adapted to release the boundary fluid into the defined volume, and that the apparatus comprises one or more means of detecting fluid characteristics arranged to monitor said fluid characteristics in a portion of the defined volume.

The means of detecting fluid characteristics may be any sensor, transducer or transmitter arranged to detect a characteristic of a fluid, such as a viscosity transmitter, a resistivity transducer or a conductivity sensor.

The defined borehole volume may typically be a region between two plugs and a tubular wall of the borehole, and may contain one or more borehole fluids.

The reservoir for storing a boundary fluid may be an integrated part of the apparatus suitable for being placed in a borehole, or it may be a remotely placed reservoir. In the embodiment where the reservoir is remotely placed, the apparatus may preferably comprise means for transferring boundary fluid from the reservoir to the defined volume. The boundary fluid may be transferred through a plug and/or through the apparatus and into the defined volume in the borehole. The means for transferring boundary fluid from the reservoir to the defined volume may be a tube.

The means for communication may be arranged to send information to a receiver and to receive information from a source. The ability to send information will allow the apparatus to transfer well condition information gathered from sensors, transmitters and/or transducers to a receiver. The ability to receive information may be used to remotely control the apparatus, such as to control when to release boundary fluid, when to activate sensors, or when to send information.

The at least one energy source may act as an energy source for the means of detecting fluid characteristics and any other energy dependent parts of the apparatus.

The apparatus may comprise one or more openings through which to release boundary fluid. The apparatus may further comprise one or more further openings, through which borehole fluids may flow into the apparatus to refill the boundary fluid reservoir as boundary fluid is released into the defined volume of the borehole.

The apparatus may comprise at least one valve to open or close for fluid flow through one or more of the openings in the apparatus, and to open or close for fluid flow into and out from the boundary fluid reservoir.

Furthermore, the apparatus may comprise a piston that aids in forcing boundary fluid from the boundary fluid reservoir into the defined volume. The same piston may also aid in the intake of borehole fluid into the boundary fluid reservoir. The apparatus may comprise other systems for moving fluid from the boundary fluid reservoir into the defined volume of the borehole, such as a pump-based system or a bladder type reservoir.

The boundary fluid may be designed and/or chosen based on specific gravity. Its specific gra vi ty may preferably be different from that of present and/or potentially present borehole fluids in the defined volume. Potentially present borehole fluids are fluids that may occur in a borehole naturally, such as reservoir fluids from the formations surrounding the borehole, or it may be fluids that may occur in the borehole as a consequence of human activities, such as fluids that are injected directly into the well or into surrounding formations. The boundary fluid is not to be seen as a fluid covered by the term potentially present borehole fluid.

Furthermore, the boundary fluid may preferably be a liquid that is immiscible, or partially miscible, with liquids present and/or potentially present in the defined volume of the borehole. Two liquids are defined as partially miscible if, when two volumes of the partially miscible liquids are shaken together, a meniscus will be visible between two layers of resulting liquid, and the two layers' volumes differ from that of the two volumes originally added. Immiscible liquids will, if shaken together, result in two layers of liquid, separated by a meniscus, wherein the two volumes of the two layers are identical to the two volumes of liquids shaken.

In a volume comprising different immiscible fluids, gravitational forces will organize them by their specific gravity, with the lightest fluid in the volume's upper portion and the heaviest fluid in the volume's lowest portion. As partially miscible fluids will also form layers, the same organization will apply to partially miscible fluids too. This principle may be tåken advantage of by the invention.

By introducing a boundary fluid with a specific gravity different from that of present and/or possibly occurring borehole fluids in the defined volume, gravitational forces will ensure that the boundary fluid at any time is arranged according to how its specific gravity compares to that of the other fluids present.

In a possible embodiment of the invention, the means of detecting fluid characteristics may be placed in such a way as to arrange for monitoring fluids in an upper portion of the defined borehole volume. In this embodiment, a boundary fluid will be chosen that has a specific gravity lowerthan that of any present or potentially present borehole liquid, and higher than that of any present or potentially present borehole gas. Thus, if there is one borehole liquid and one borehole gas present in the defined volume, and the boundary fluid is added, gravitational forces will ensure that the borehole gas sits atop the boundary fluid which in turn sits atop the borehole liquid.

In a typical case where the apparatus is used, it is not known whether there is gas in the defined borehole volume, neither is it known whether there is a leak e.g. in a plug defining said volume's upper border. By using the apparatus, arranged with the means for detecting fluid characteristics covering an upper portion of said volume, it will be possible to determine if there is a gas present and if there is a leakage in the plug.

If no gas is present, and there is no leak in the plug, the fluid characteristics detected will be consistent with those of the boundary fluid.

If a gas is present and there is no leak in the plug, the boundary fluid will be displaced downwards, and the fluid characteristics of the gas will be detected.

If there is a leak in the plug, the boundary fluid will move upwards, out of the defined volume, and the fluid characteristics detected will be those of a heavier borehole liquid.

The boundary fluid may be miscible with present and/or potentially present borehole fluids. If fluid characteristics data is gathered from the fluids present in a defined volume in a well, it is possible to calculate how the characteristics should change by introducing a miscible boundary fluid with known characteristics into the defined volume. By measuring how characteristics actually does change over time after release of a miscible borehole fluid with known characteristics into a defined volume containing one or more fluids with known characteristics, and compare the measured data with calculated expectations, it will be possible to make deductions regarding the conditions in the defined volume, such as if there is a leak or if there is gas present in the defined volume.

The apparatus may comprise means of anchoring the apparatus to a tubular wall. The apparatus may comprise a plug comprising anchoring means for anchoring to a tubular wall. The plug may be

a mechanical tubular plug.

Any combination of means and method suitable for anchoring the apparatus to a tubular known to a person skilled in the art may be used for the purpose. As these combinations of means and methods for anchoring the apparatus to a tubular are known, they will not be discussed in detail in this text, nor explained or shown in detail in the embodiment descriptions.

Furthermore, the apparatus may comprise a logic solver for data processing. The logic solver may receive data from the means of detecting fluid characteristics. This data may be processed by the logic solver. The logic solver may be programmed to perform activities such as transfer signals through a signal transferring mechanism to a receiver outside of the borehole, to translate the signals and then send them as described, or to interpret the signals and send signals as described given certain conditions, such as if a leak is detected, a temperature or pressure change is detected, or gas is perceived to be present. The logic solver may further receive and process data from other sources.

The apparatus may further comprise means for monitoring temperature, such as a temperature sensor, transducer or transmitter.

Furthermore, the apparatus may comprise means for monitoring pressure, such as a pressure sensor, transducer or transmitter.

The means for communication may be means for acoustic communication. Said means may comprise one or more signal generators and/or one or more signal receivers. A signal generator may comprise a coil, a bolt and an anvil. A receiver may comprise an accelerometer. A receiver may be remotely placed from the defined volume, such as at the surface of the borehole.

The means for acoustic communication may be arranged to transfer information acoustically via a tubular. Communication via a tubular is advantageous in that it allows for passing obstructions in a borehole, such as plugs or other barriers.

An acoustic signal may be propagated either as a body wave or as a surface wave in an elastic medium with rigidity, such as iron or steel. Surface waves contain little energy and are quickly absorbed by the body's surroundings and are therefore of little use to propagate a signal over a useful distance. Surface waves are often used in ultrasonic inspection equipment.

Body waves are of two types: Primary waves (also called P-waves or pressure waves) and Secondary waves (S-waves or shear waves).

In a body wave the acoustic energy is transferred as a longitudinal wave (P-wave) or as a transverse wave (S-wave) through an elastic medium with rigidity. P-waves may also propagate in liquid or gaseous materials, whereas S-waves only propagate in solid material, as shear forces.

A P-wave is a body wave that moves particles within the body back and forth in the same direction and the opposite direction of the direction the wave is forming and is formed by alternating compressions and rarefactions. An S-wave is a body wave that shakes the body back and forth perpendicular to the direction the wave is moving.

For the purpose of transferring information via a tubular, the P-waves are by far the most efficient and useful. When this text refers to acoustic signals axially oriented relative to the tubular, it refers to the direction of the P-waves of the acoustic signals in the tubular. The acoustic signals are produced and transferred into the tubular in such a way that the direction of the P-waves substantially approximates the axial direction of the tubular.

The apparatus may comprise means for intrusion into a tubular wall at a desired location, such as the teeth of a mechanical tubular plug's locking device. Any mechanism suitable for the purpose of forcing the means for intrusion into the tubular wall may be applied, such as a jarring mechanism or a hydraulic system.

The signal generator may be arranged to generate acoustic signals with a P-wave direction substantially approximating the axial direction of the tubular at said desired location. Furthermore, the means for intrusion into a tubular wall may be arranged to retain the axial direction of the acoustic signals' P-waves when transferring the signals into the tubular. This may be done by arranging the means for intrusion such that an upper and/or a lower side of the means for intrusions, when set into a vertical tubular, are formed to be perpendicular to the axial direction of the tubular.

The apparatus may further comprise a mechanical barrier element, separating a first section of the apparatus and a second section of the apparatus. The first section may comprise sensors, transmitters or transducers arranged to monitor pressure and/or temperature, and/or fluid characteristics in a part of the borehole not part of the defined volume. The first section may further comprise means of communicating with the second section of the apparatus and/or with other sources, such as one or more signal generators for generating acoustic signals and one or more receivers for receiving acoustic signals. The first section may further comprise an energy source, such as a battery, and a logic solver for processing data. The second section may comprise anything mentioned in this text as elements that may or must be comprised by the apparatus.

In a second aspect the invention relates to a method for gathering information about the conditions in a defined volume in a borehole by means of the apparatus according to the first aspect of the invention, wherein the method comprises releasing a boundary fluid into the defined volume, and consequently measuring fluid characteristics in a portion of said volume.

The method may further comprise measuring pressure and/or temperature in the defined volume, and/or measuring pressure and/or temperature in a non-defined volume on the opposite side of a well barrier defining the upper or lower border of the defined volume.

Furthermore, the method may comprise interpreting data from measurements and/or translating said data to signals suitable for transferring information acoustically.

The method may further comprise generating acoustic signals.

The method may further comprise intrusion into a tubular, at a chosen location, by use of means for intrusion into a tubular.

Furthermore, the method may comprise transferring the acoustic signals via one or more mechanical elements to means for intrusion into a tubular, and further transferring said acoustic signals into the tubular via said means for intrusion into a tubular. The method may comprise generating the acoustic signals comprising P-waves håving a direction substantially approximating the axial direction of said tubular at the location of intrusion into the tubular.

The method may further comprise receiving the acoustic signals at the surface of the borehole, or at another suitable location.

Furthermore, the method may comprise receiving information in the defined volume in the borehole, such as information used to remotely control the apparatus in the first aspect of the invention.

The method may further comprise communicating through a barrier between a first section and a second section of the apparatus according to the first aspect of the invention.

Furthermore, the method may comprise receiving information and relaying said information to at least one other receiver.

All actions described as possible parts of the method may be performed by use of the apparatus in the first aspect of the invention.

In the following is described an example of a preferred embodiment illustrated in the accompanying drawings, wherein: Fig. 1 shows the apparatus for releasing and monitoring a boundary fluid in an embodiment

comprising a plug and means for transferring information acoustically; and

Fig. 2 shows an embodiment of the apparatus' means for intrusion into a tubular wall intruding into a tubular wall.

In said preferred embodiment, illustrated in figure 1, the apparatus 1 for monitoring conditions in a defined volume V in a borehole, comprising a plug 10, is placed in the defined volume V. The defined volume V is limited at one end by the plug 10, at the opposite end by other means not shown in the illustration, e.g. the bottom end of the borehole or another plug, and radially by a tubular 20 wall.

The apparatus 1 comprises a physical barrier element 9. The element 9 separates a first section 11of the apparatus 1 from a second section 12of the apparatus 1. The apparatus 1, comprising the plug 10, further separates the defined volume V in the borehole from a non-defined volume V in the borehole.

The first section 11of the apparatus 1 comprises a battery 4', for providing power to any parts in

the first section 1i of the apparatus 1 requiring energy. The first section 1i further comprises a logic solver 3', for processing data, a receiver 142, for receiving acoustic data, a signal generator 133, for generating acoustic signals, a temperature transmitter I62and a pressure transmitter 152, for monitoring temperature and pressure in the non-defined volume V in the borehole.

In the second section I2of the apparatus 1, the apparatus 1 further comprises a boundary fluid reservoir 6, and an actuator 18 that controls a piston valve 8. Furthermore, the second section I2comprises holes 2i, 22, 7i and 72. If the piston valve 8 is open, the holes 22and 72will be open, which will allow for fluid to flow into and out from the boundary fluid reservoir 6. In a typical situation, where an immiscible boundary fluid has a lower specific gravity than the borehole fluid present in the borehole surrounding the apparatus 1, and the piston valve 8 is open, gravitational forces will make the heavier borehole fluid flow into the boundary fluid reservoir 6 through holes 7i and 72, and displace the lighter boundary fluid from the boundary fluid reservoir 6 into the borehole through holes 22and 2i.

The apparatus' 1 second section I2further comprises a range of sensors 5i - 5io, arranged to monitor fluid characteristics in a portion of the defined volume V, and a battery pack 4, comprising five batteries, to provide energy to the sensors 5i - 5io and any other parts on the second section I2of the apparatus 1 that requires energy.

Furthermore, the second section I2of the apparatus 1 comprises a temperature transmitter 161, for monitoring temperature in the defined volume V, and a pressure transmitter 15i, for monitoring pressure in the defined volume V. The second section I2of the apparatus 1 further comprises a logic solver 3, for processing data.

The second section I2of the apparatus 1 further comprises signal generators 13i and 132for generating acoustic signals, and a receiver 14i for receiving acoustic data. By use of one or more of the signal generators 13i-132and the receiver 14i, and the signal generator 133and the receiver 142, the two sections 1i, I2of the apparatus 1 can communicate with each other. The signal generators 13i-133and the receivers 14i-142further facilitates for communication to and/or from the apparatus 1 to and/or from other sources, e.g. on the surface.

The plug 10 comprises a locking bolt 19, an upper pressure seal 211, a lower pressure seal 212, and two locking dogs 17i and 172. Each locking dog comprises a set of teeth, constituting the apparatus' 1 means for intrusion into a tubular wall 101. The set of teeth intrudes into the tubular wall, where they acts as means for transferring acoustic signals from the apparatus 1 into the tubular 20, and from the tubular 20 to the apparatus 1.

Figure 2 shows the means for intrusion into a tubular wall 101 intruding into the tubular wall, in an embodiment where the upper sides of the means for intrusion into a tubular wall 101 are arranged such that they are perpendicular to the axial direction of the tubular 20 upon intrusion. The purpose of the perpendicular intrusion is to ensure a signal transfer into the tubular 20 wall that retains the direction of the P-waves; that the P-waves of the acoustic signals retains a direction substantially approximating the axial direction of the tubular 20.

It should be noted that the above-mentioned embodiments illustrate ratherthan 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 arti ele "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. It should also be noted that the various features in the fig ures are not necessarily drawn to scale.

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.

Claims

1. Apparatus (1) for monitoring conditions in a defined volume (V) in a borehole, the defined volume (V) containing one or more borehole fluids, the apparatus (1) comprising a reservoir (6) for storing a boundary fluid, the apparatus (1) further comprising at least one energy source (4, 4') and means for signal communication (13i-133,14i, 142),characterised in that; - the apparatus (1) is adapted to release the boundary fluid into the defined volume (V); and - the apparatus (1) comprises one or more means of detecting fluid characteristics (5i-5io), the means of detecting fluid characteristics (5i-5io) arranged to monitor said fluid characteristics in a portion of the defined volume (V).

2. The apparatus (1) according to claim 1, wherein the reservoir (6) is arranged to be placed in the defined volume (V) in a borehole.

3. The apparatus (1) according to claim 1, wherein the reservoir (6) is arranged to be remotely placed from said defined volume (V), the apparatus (1) comprising means for transferring the boundary fluid from the reservoir (6) into the defined volume (V) in a borehole.

4. The apparatus (1) according to any one of the previous claims, wherein the boundary fluid has a specific gravity different from that of present and/or potentially occurring borehole fluids.

5. The apparatus (1) according to any one of the previous claims, wherein the boundary fluid is a liquid that is immiscible with any present and/or potentially occurring borehole fluids.

6. The apparatus (1) according to any one of the claims 1-4, wherein the boundary fluid is miscible with one or more present and/or potentially occurring borehole fluids.

7. The apparatus (1) according to any one of the previous claims, the apparatus further comprising means for anchoring the apparatus (1) to a tubular (20) in a well.

8. The apparatus (1) according to claim 7, comprising a mechanical tubular plug (10), wherein the plug's (10) means for anchoring to a tubular wall (101) comprises the apparatus' (1) means for anchoring to a tubular wall (101).

9. The apparatus (1) according to any one of the previous claims, further comprising a logic solver for processing data (3).

10. The apparatus (1) according to any one of the previous claims, further comprising means for monitoring pressure (15i, 152).

11. The apparatus (1) according to any one of the previous claims, further comprising means for monitoring temperature (16i, I62).

12. The apparatus (1) according to any one of the previous claims, wherein the means for signal communication comprises means forsending information to a receiver (13i-133) and means for receiving information (14i, 142).

13. The apparatus (1) according to any one of the previous claims, wherein the means for signal communication (13i-133,14i, 142) are means for communicating acoustically (13i-133, 14i, 142).

14. The apparatus (1) according to claim 13, comprising at least one signal generator (13i-133) for generating acoustic signals, comprising means for intrusion into a tubular wall at a desired location (101), wherein the at least one signal generator (13i-133) is arranged to generate acoustic signals with a P-wave direction substantially approximating the axial direction of said tubular (20) at said desired location, wherein the means for intrusion into a tubular wall at a desired location (101) are adapted to transfer the acoustic signals into the tubular (20).

15. The apparatus (1) according to any of the previous claims, comprising a barrier element (9), wherein the barrier element (9) separates the defined volume (V) of the borehole from a non-defined volume of the borehole, wherein the barrier element (9) further separates a first section (1i) of the apparatus (1) from a second section (I2) of the apparatus (1), wherein both the first section (1i) and the second section (I2) comprises at least one signal generator (13i-133), at least one receiver (14i, 142), at least one sensor, transducer or transmitter for monitoring conditions (15i, 152,161, I62), at least one logic solver (3, 3') and at least one energy source (4,4').

16. Method for monitoring conditions in a defined volume in a borehole by means of an apparatus (1) according to claim 1,characterised in thatthe method comprises the release of a boundary fluid into the defined volume (V) and the subsequent detection of fluid characteristics in a portion of the defined volume (V).