Plug sensor with ceramic element

The present invention relates to an apparatus for measuring different parameters in an oil and/or gas well and, more specifically, the present invention relates to at least one sensor in a tubular element installed offshore or onshore, wherein the at least one sensor is used, for example, to measure pressure and/or temperature in the oil and/or gas well.

During well completion of a fully drilled oil and/or gas well, a number of casings of different lengths and diameters will be cemented to the ground formation. Between the casings, which are disposed coaxially with each other, a so-called annulus will be formed. To prevent a leakage in the oil and/or gas well, a plurality of packer elements will suitably be arranged between the casings. The casings will be suitably suspended from a wellhead structure, where the wellhead structure is arranged at the top of the oil and/or gas well. During operation of the oil and/or gas well, the wellhead structure will conduct the well stream therethrough for further processing of the well stream. The wellhead structure will also be a safety mechanism against the well stream flowing uncontrolled to the surface.

A wellhead structure of this kind is subjected to large loads and stresses from the surrounding environment. Although these structures and installations are designed to be maintenance-free for a number of years, they must be inspected constantly for safety and financial reasons.

It is both desirable and necessary to carry out an inspection of such offshore installations, for example, various equipment, pipelines, wellheads etc., not only during production, but also during drilling, installation and maintenance and repair work, this inspection taking placed in the form of automated operations. This means that quite different demands are made on the equipment and monitoring, inspection and communication systems that are used offshore than what is normal for installations onshore.

In addition to the above, it will be extremely important to know how an oil and/or gas well is behaving, or what is happening in the oil and/or gas well, and this will be the case throughout the entire lifetime of the well, i.e., from when the actual drilling of the well starts until the well is finally shut down. This is done by monitoring a number of different parameters in the well, which parameters may for example be contamination, leaks, well pressure, the production itself, sand/erosion in the well, wellhead temperature, the state or condition of various equipment (for example, the position of a valve), corrosion etc.

In connection with, for example, production of oil and/or gas wells, it will be extremely important from a safety, reliability and cost aspect to prevent a so-called pressure leak from the well through the different annuli in the casings, and out to the surroundings. If an undesirable pressure leak of this kind nevertheless occurs, various safety systems are intended to be able to close the well even under pressure, so that well fluid which has flowed into the different annuli of the well can circulate out in a controlled manner.

By carrying out constant measurements of, for example, the pressure in the well, where this can be done at a number of different points in the well, it will be possible to have at an earlier point in time an indication that a pressure increase is about to occur in the well, that a pressure leak in the well will or has already occurred, whereby various actions can be taken to ensure that the consequences of such a pressure build-up will be minimal or to prevent them altogether.

Various solutions have therefore been developed to monitor and/or control pressure in an oil or gas well, Reference can be made, for example, to U.S. Pat. No. 5,172,112, in which there is known that a pressure-measuring device measures pressure in a subsea pipe. The device includes a stationary unit mounted to the exterior of the subsea pipe and a movable unit that is lowered into position next to the stationary unit whenever the pressure is to be monitored or measured. The stationary unit, which is a strain gauge, will monitor the pressure in the pipe by measuring the “strain” in the pipe. The measurements will subsequently be transmitted from the stationary unit in the form of suitable signals, whereby the movable unit will then convert these signals to give a picture of the pressure that is within the subsea pipe.

A solution is known from GB 2 286 682 where an inductive pressure transducer is used to measure the pressure within a pipe. This is accomplished by passing an alternating current within an inductor coil to generate a magnetic field. The magnetic field passes through a gap formed between the pipe and the inductor coil, and then into the pipe. The fluid flowing in the pipe will, owing to its pressure, induce stress in the pipe, which stress will cause variations in the electromagnetic properties of the material from which the pipe is made, which variations can be sensed by the magnetic field that is formed. The sensed variations can then be converted to give a pressure measurement.

A feature common to the solutions described above is that the pressure-measuring device is not arranged through the material of the measuring element. This means that the pressure-measuring device can be replaced without any danger of a leakage or the like occurring during the replacement thereof, but on the other hand these known solutions will not give a satisfactory measurement as the measuring element may be affected by the ambient temperature, loads to which the measuring element is subjected etc.

Another system for detecting a leakage in an oil and/or gas well is described in U.S. Pat. No. 4,116,044, where the system comprises a plurality of pressure-sensitive transducers that are arranged in a through hole in a wellhead. The pressure-sensitive transducers will be so arranged that they can detect a leakage in a plurality of annuli in the well. The transducers are connected through wires to a junction box which will be capable of carrying signals to a processing location. During replacement of the transducers, the well will have to be shut down as the replacement operation will involve the well being “opened”.

It is an object of the present invention to provide an apparatus for measuring different parameters, where the apparatus can be used in a monitoring system for oil and/or gas wells.

Another object of the present invention will be to provide an apparatus which provides a double barrier in the apparatus for measuring different parameters.

A further object of the present invention will be to remedy or reduce at least one of the disadvantages of the prior art.

The aforementioned objects according to the present invention are achieved by means of an apparatus for measuring different parameters as disclosed in independent claim 1, with additional embodiments of the present invention disclosed in the dependent claims and the description below.

An apparatus for monitoring physical parameters in an oil and/or gas well according to the present invention can in one application be used in a monitoring system which measures and monitors different parameters in an oil and/or gas well, for example, pressure and/or temperature, the monitoring system being designed so as to be capable of monitoring a number of different zones or areas in an oil and/or gas well. The purpose of the monitoring will be, through the measurements made, to see at an early stage that a pressure leak in the well is in the process of occurring, or already has occurred, thereby allowing various actions to be taken to prevent or even to limit the damage caused by the pressure leak. The apparatus for monitoring physical parameters can in a typical use be connected to a wellhead in the oil and/or gas well. However, it should be understood that the apparatus for monitoring physical parameters may also be used in other connections.

The apparatus for monitoring physical parameters in an oil and/or gas well according to the present invention comprises a flange assembly that is configured with a through bore and an end termination that is to seal or close an end of the apparatus, where a sensor and associated electronics are arranged in the through bore. The sensor will, via transmission devices, for example in the form of wires or the like, which are passed through a ceramic element, be connected to the associated electronics. Wires or the like may then be embedded in the ceramic element.

The sensor will then be able to measure different parameters in the oil and/or gas well, after which these “measurements” in the form of suitable signals will be transmittable to the associated electronics. The associated electronics will then either be able to process the received signals themselves, or send these signals to another receiving and/or processing unit for further processing. This can be achieved in that the associated electronics can be connected to the receiving and/or processing unit via one or more electric wires, one or more signal cables etc., or even wirelessly.

In an embodiment of the apparatus for monitoring parameters there is provided one or more batteries or battery packs, which will supply the sensor, associated electronics etc. in the apparatus with necessary power as required. However, this can also be accomplished by connecting the apparatus to one or more power supplying wires.

In an embodiment, the ceramic element may be so configured that it allows a current passage through the ceramic element, which ceramic element in specific through-going lines or areas through the longitudinal direction thereof is then made of a mixture of a ceramic material and a conducting material (for example, platinum), so that current can be transferred across the ceramic element. In this connection, it should also be understood that the ceramic element may be composed of several ceramic pieces along its longitudinal direction, which ceramic pieces, when assembled, will then form the ceramic element. The current passage can also be obtained by using metallic or other electrically conducting materials. A person of skill in the art will understand how this can be accomplished, and therefore this is not discussed further here. Wires or the like can then in a suitable manner be configured to be capable of being connected to each side of the ceramic element, so as to obtain a current passage through the ceramic element.

The ceramic element will, moreover, be designed to form a pressure-tight connection in the apparatus, so as to prevent a (fluid) leakage from occurring over the ceramic element.

Owing to its design, the ceramic element will, moreover, also be pressure-tight.

To be able to connect the ceramic element in the apparatus, the ceramic element is arranged in a sleeve, which sleeve is along a part of its length configured with a threaded portion. A corresponding threaded portion internally in the through bore in the apparatus will then be formed, so as to allow the sleeve containing the ceramic element to be connected to the apparatus.

In an embodiment of the present invention, the sensor is only designed to measure pressure and temperature, but it should be understood that the sensor may also be designed so as to be capable of measuring other parameters or additional parameters. It should also be appreciated that other devices may be used to carry out the desired measurements.

Furthermore, the sensor could be configured with a threaded portion along a part of its length, thereby enabling the sensor to be screwed to a tubular element, for example, a wellhead.

In an embodiment of the present invention, the flange assembly is constituted of a front and a rear flange portion, where the rear flange portion overlaps a part of the front flange portion when they are assembled. The front and the rear flange portion will further be connected to each other by bolts, screws or the like, there additionally being provided one or more sealing devices, for example, O-rings or the like, between the overlapping parts of the front and rear flange portions, so as to provide a fluid-tight connection between them.

In order to be able to seal off one end of the apparatus when the apparatus is fixedly connected to a tubular element, for example, a wellhead, Christmas tree or the like, the end termination is configured with a projection, for example, in the form of a sleeve, at a distance from its outer periphery, which projection, when the end termination is connected to the rear flange portion, will extend a distance into the rear flange portion and essentially be in contact with the interior of the through bore in the rear flange portion. One or more sealing devices, for example, O-rings, are disposed between the overlapping portions of the end termination and the rear flange portion in order to provide a fluid-tight connection between them. The rear flange portion and the end termination are connected to each other by bolts, screws or the like.

It should be understood that the flange assembly may comprise more or fewer elements.

The flange assembly, the through bore therein and the end termination will, in a preferred embodiment of the present invention, have a circular shape, but it should also be understood that square, rectangular or other polygonal shapes may be used, both for the flange assembly and the through bore.

In an embodiment, the apparatus for monitoring physical parameters according to the present invention is arranged so as to be able to communicate with other similar apparatus. This may be done by connecting two or more apparatus together with the aid of at least one wire. The communication between the various units may also take place wirelessly. How this is done and what means are necessary to achieve such communication will be known to a person of skill in the art, and therefore a more detailed description will not be given here.

Thus, by means of the present invention an apparatus is provided that can be used in connection with a temperature and pressure monitoring system which allows the sensors in the system to be mounted or demounted under pressure, i.e., that the oil and/or gas well may be in production whilst the mounting/demounting is carried out; the system will further preserve the barriers in the safety system and any pressure leaks in the oil and/or gas well will to far greater extent be prevented in that an indication of “abnormal” conditions in the well is given at an earlier stage.

Other advantages and special features of the present subject invention will be made clear in the following detailed description, the attached drawings and the following patent claims.

The present invention will now be described with reference to several embodiments of the invention as shown in the figures, wherein:

FIG. 1 is a schematic outline of a typical wellhead structure, comprising a temperature and pressure monitoring system;

FIG. 2 shows a first embodiment of an apparatus according to the present invention, seen in a partial side view and in a cross-section;

FIG. 3 shows a second embodiment of the apparatus according to the present invention, seen in a cross-section; and

FIG. 4 shows a third embodiment of the apparatus according to the present invention seen from the rear and in a cross-section.

FIG. 1 shows a typical wellhead structure that is used in connection with an oil and/or gas well, where a wellhead 1, at its upper end, is connected to a riser 2 which extends between a floating structure (not shown), for example, a platform or the like, and the wellhead 1. A first casing 3 extends a distance down into a surface formation and is cemented to the surface formation O. The upper end of the first casing 3 is suitably suspended from the wellhead 1, sealing devices 4 in the form of one or more packers being arranged between an exterior surface of the first casing 3 and an interior surface of the pressurised housing H of the wellhead 1. Within the first casing 3 there is arranged another, second casing 5, which will then extend through the first casing 3 and a longer distance down into the surface formation O than the first casing 3. The second casing 5 will, like the first casing 3, be cemented to the surface formation O. The second casing 5 will in addition be partly supported by (suspended in) the first casing 3. In order to obtain a tight connection between an interior surface of the first casing 3 and the exterior surface of the second casing 5, sealing devices 4 are provided between the first and the second casing 3, 5. As the second casing 5 has a smaller diameter than the first casing 3, a space will be formed between the first and the second casing 3, 5, which space is called an annulus. The space that is delimited by the interior surface of the first casing 3, the second casing 5 and the casing hanger in the first and the second casing 3, 5 will define a first annulus A. As described above for the first and the second casing 3, 5, a third casing 6 will run internally through the second casing 5, and will be supported by (suspended in) the second casing 5. The third casing 6 will have a diameter that is smaller than the diameter of the second casing 5. Here, the second and the third casing 5, 6, together with the casing hanger in the second and the third casing 5, 6, will define a second annulus B. Within the third casing 6 there is arranged a last and fourth casing 7, through which fourth casing 7 a production tubing (not shown) will run when the oil and/or gas well is in production. The fourth casing 7 will have a diameter that is smaller than the diameter of the third casing 6. The space that is formed between the third and the fourth casing 6, 7 and the casing hanger in the third and the fourth casing 6, 7 will form a third annulus C. To obtain a tight connection between an interior surface of the second and the third casing 5, 6 and the exterior surface of the third and the fourth casing 6, 7, sealing devices 4 are provided between the second and the third casing 5, 6 and the third and the fourth casing 6, 7.

The wellhead 1 may furthermore be connected to a blow-out valve (not shown), a so-called BOP (Blow Out Preventer).

The above wellhead structure will provide a fluid and pressure-tight system, but conditions in the oil and/or gas well might mean that the sealing devices 4, owing, for example, to large pressure build-ups in the well, temperature variations, or their service life, might begin to “leak”, such that a pressure leak occurs in the well, where this is not desirable.

In order to prevent such undesired pressure leaks, a plurality of apparatus for measuring different parameters 8, which will be explained in more detail in connection with remaining FIGS. 2 to 4, will be arranged along the length of the wellhead 1, such that measurement and monitoring of different parameters, for example, pressure and/or temperature, can be carried out in each of the annuli A-C in the well. The wellhead 1 will then be configured with a plurality of through holes (not shown), to which holes the apparatus 8 can suitably be connected. The measurements made in each of the annuli A-C may be suitably transmitted to, for example, a floating structure for processing and monitoring.

FIG. 2 shows a first embodiment of a measuring or monitoring apparatus 8 according to the present invention, where the apparatus 8 is shown partly from the side and in a cross-section, when connected to the wellhead 1. The wellhead 1 will then be configured with a plurality of through holes 9, which holes 9 will then be so positioned as to lead in to each of the annuli A-C. The apparatus 8 comprises a sensor 10 and a flange assembly 11, which are fixedly connected to each other. The flange assembly 11 is constituted of a front flange portion 12 and a rear flange portion 13, which via a plurality of bolts 14 or the like are connected to each other. An end of the rear flange portion 13 will then be so configured that it overlaps an end of the front flange portion 12 when the front and the rear flange portion 12, 13 are assembled. Both the front and the rear flange portion 12, 13 will furthermore be configured with a groove or recess 16, in which recess 16 an 0-ring 17 is arranged when the front and the rear flange portion 12, 13 are connected to each other, so as to provide a fluid-tight connection between them.

The flange assembly 11 is further configured with a through bore 14, in which bore 14 the sensor 10 and the associated electronics 15 are arranged. A second end (opposite the end that is connected to the rear flange portion 13) of the front flange portion 12 will then be configured with a contact face 18 for the sensor 10, the said contact face 18 forming a stop edge for the sensor 10. The sensor 10 will then similarly be configured with a face 19 that will bear against the contact face 18 in the front flange portion 12, such that the sensor 10 is positioned correctly in relation to the wellhead 1. The sensor 10 will furthermore, along a part of its length, be configured with a threaded portion 20, such that the sensor 10 can be screwed into the hole 9 in the wellhead 1. The hole 9 in the wellhead 1 will then be configured with a complementarily threaded portion (not shown).

The sensor 10 comprises an electronic printed circuit board 21, which via wires 22 is connected to a separate main printed circuit board 23 arranged in the bore 14 in the front flange portion 12. Through this configuration, the sensor 10, comprising the electronic printed circuit board 21, will be separated from the main printed circuit board 23, the sensor 10 being arranged at the end of the front flange portion 12 which lies closest to the wellhead 1, whilst the separate main printed circuit board 23 will be arranged at an opposite end of the front flange portion 12, adjacent to the rear flange portion 13. Between the sensor 10 and the separate main printed circuit board 23 there is disposed a ceramic element 24. Wires 22 connecting the sensor 10 and the separate main printed circuit board 23 may extend through the ceramic element. In one embodiment, the wires 22 will, however, not run through the whole of the ceramic element 24, only a certain length into the ceramic element 24, such that wires 22 from sensor 10 and wires 22 to the main printed circuit board 23, when arranged in the ceramic element 24, will be located at a distance from each other. The ceramic element 24 is however so configured that through at least one through-going portion or area through the ceramic element 24 there is arranged a mixture of a ceramic material and an electrically conducting material (for example, platinum). This will mean that the ceramic element 24 will form a pressure-tight barrier in the apparatus 8. The ceramic element 24 is in a fluid and/or pressure-tight way connected to a sleeve 25. The sleeve 25 is further configured with a threaded portion (not shown) and a varying cross-section along its length. The current passage through the ceramic element 24 may however be achieved by, for example, using metallic or other electrically conducting materials.

The through bore 14 in the front flange portion 12 will along a part of its length be configured with a varying cross-section, which varying cross-section will be complementarily configured with the varying cross-section of the sleeve 25. A rear edge 26 of the varying cross-section in the through bore 14 will, when the sleeve 25 with the ceramic element 24 is arranged in the varying cross-section of the through bore 14, together with an end of the sleeve 25, form a tight connection between the front flange portion 12 and the sleeve 25. This forms a fireproof connection in the apparatus 8.

The rear flange portion 13 is configured with a through and threaded hole 27, so as to enable a cable lead-in 28, comprising a tensioning nut 29, to be connected to the threaded hole 27. Between the contact faces of the rear flange portion 13 and the cable lead-in 28 there is arranged a seal 30 in the form of an O-ring. An electric cable E is then passed through the cable lead-in 28 and connected to a connecting printed circuit board 31 in the though bore 14 in the flange assembly 11.

The separate main printed circuit board 23 and connecting printed circuit board 31 are, by means of a securing device 32, connected to a rear wall 33 of the front flange portion 12. The securing device 32 will further ensure that the main printed circuit board 23 and the connecting printed circuit board 31 are arranged at a distance from each other. Signals received from the sensor 10 will then be wirelessly transmittable from the main printed circuit board 23 to the connecting printed circuit board 31, in order thus, through the electric wire E, to be transmitted for processing on a floating structure (not shown).

The rear flange portion 13, which is an “open” sleeve, is, at an end opposite the end overlappingly connected to the front flange portion 12, configured for being connected to an end termination 34, such that the apparatus 8 can be closed or sealed at the end opposite the connection to the wellhead 1. The end termination 34 is then configured with a plurality of through openings 35, which through openings 35 are used for passage of bolts 36. An end termination in the rear flange portion 13 will then be configured with a plurality of threaded holes 37 for receipt and screw fastening of bolts 36.

The end termination 34 will on one side be configured with a projection 38, which projection 38 will be such that it essentially corresponds to the through bore 14, such that the projection 38 will extend a certain distance into the rear flange portion 13 when the end termination 34, via the bolts 36, is connected to the rear flange portion 13. A seal 39 in the form of an O-ring is arranged between the interior surface of the rear flange portion 13 and the exterior surface of the projection 38, one or both of these surfaces then being configured with a groove for receiving the seal 39.

Furthermore, the front flange portion 12, in a face A which forms contact with the wellhead 1, is configured with a plurality of holes 41, such that bolts and nuts 42 can be used to fixedly connect the apparatus 8 to the wellhead 1. Face A is further configured with a recess 43 for receiving a sealing element 44 such that a tight connection is provided between the apparatus 8 and the wellhead 1 when they are connected to each other.

FIG. 3 shows another embodiment of the apparatus 8 according to the present invention, where the apparatus 8 is now configured so as to be able to transmit signals from the sensor 10 wirelessly. With the exception of how the transmission of signals takes place according to this embodiment, the general component composition of the apparatus 8 and its operating principle are the same as described for the first embodiment of the invention as shown in FIG. 2, and so for the sake of simplicity they are not described again.

The embodiment shown in FIG. 3 uses a wireless transmission of signals from the sensor 10, where the rear flange portion 13 will be configured with a through and threaded hole 27, so as to enable a wireless antenna 44 to be connected to the through and threaded hole 27. A securing device 32 is also used in this embodiment to connect the separate main printed circuit board 23 and the connecting printed circuit board 31 to the rear wall 33 of the front flange portion 12. However, the distance between the main printed circuit board 23 and the connecting printed circuit board 31 will now be greater than in the embodiment described with reference to FIG. 2, seen in relation to the fact that a part of the wireless antenna 44 will extend a distance into the through bore 14 in the flange assembly 11. Signals received from the sensor 10 will then be wirelessly transmittable from the main printed circuit board 23 to the connecting printed circuit board 31, so as to be further transmittable wirelessly from the connecting printed circuit board 31 to the wireless antenna 44, in order to be further transmitted wirelessly for processing on a floating structure (not shown). For signal amplification, a plurality of signal amplifying units (not shown) may be provided between the wellhead and the floating structure.

To operate the sensor 10 and/or the wireless antenna 44 in the apparatus 8, a battery or a battery pack 45 is provided in the apparatus 8 when the apparatus 8 is assembled. This embodiment will mean that the battery or battery pack 45 can easily be replaced by unscrewing bolts 36 in the end termination 34 and removing the end termination 34 from the rear flange portion 13. The battery or battery pack 45 can in a suitable manner, for example, by means of wires etc. (not shown), be connected to the connecting printed circuit board 31.

The battery or battery pack 45 may also be connected to, or comprise a device (not shown) capable of ensuring that the battery or battery pack 45 is turned off and on at certain time intervals. The device can then turn the battery or battery pack 45 on for a pre-specified time unit (minutes, hours or days), so as to allow the desired number of measurements of, for example, pressure and temperature to be carried out, after which the device will turn the battery or battery pack 45 off. However, it should be understood that such a device must also comprise the possibility of being overridden, seen in relation to the fact that measurements with the apparatus 8 may also be carried out outside the pre-specified time units.

FIG. 4 shows an additional embodiment of the apparatus 8 according to the present invention, where the rear flange portion 13 in the apparatus 8 is configured with several through and threaded holes 27. The general component composition of the apparatus 8 and its operating principle are the same as described for the first embodiment of the invention as shown in FIG. 2, and so for the sake of simplicity they are not described again.

Configuring the rear flange portion 13 with several through and threaded holes 27, will enable the apparatus 8 to be connected to two electric cables E, an electric cable E and a wireless antenna 44, or even two wireless antennas 44. Alternatively, one of the through and threaded holes 27 can initially be closed by a stop plug 46. If, for example, the electric wire E or the wireless antenna 44 for some reason is knocked off or damaged there will be the possibility of connecting to the apparatus 8 by removing the stop plug 46 and, for example, coupling a wireless antenna 44 to the other through and threaded hole 27.

In addition, this embodiment will also permit several similar apparatus to be connected on the same line, where the apparatus will then be able to communicate with each other digitally.

The invention has now been explained by referring to some non-limiting examples. A person of skill in the art will understand that it will be possible to make a number of variations and modifications to the temperature and pressure monitoring system as described within the scope of the invention as defined in the attached claims.

Plug sensor with ceramic element

Information

Publication Number

Date Filed

Date Published

Inventors

Original Assignees

CPC

US Classifications

International Classifications

Abstract

Description

Claims

Priority Claims (1)

PCT Information