MXPA01000486A - Downhole well corrosion monitoring apparatus and method - Google Patents

Abstract

The existence and rate of corrosion in a section of a well tubing or well casing is determined and monitored by installing at predetermined locations as the string is placed in the well bore, sections of pipe (20) that have been fitted with an array of piezoelectric transducers (26) and a microprocessor (28) that controls signals going to and from each array of transducers and signals going to and received from controls and intrumentation apparatus located at the earth's surface. The microprocessors at varying locations along the string are electrically connected to the surface control and instrumentation apparatus by conductor cables and/or by wireless means using the pipe string as the conductive path for electrical signals.

Description

APPARATUS AND METHOD FOR CORROSION SUPERVISION IN DESCENDING HOLE WELL FIELD OF THE INVENTION The invention relates to the ultrasonic monitoring of the condition of well piping and well casing string during operation or while the well is enclosed to identify the beginning and location of the corrosion, and its progress rate in any type of well environment, including oil, gas, water and multi-phase fluids.

BACKGROUND OF THE INVENTION A variety of devices and methods have been employed in an effort to detect and / or monitor the progress of corrosion in well pipe strings, or pipes, and well casing strings, and the process is widely referred to as corrosion monitoring of "down hole". As used herein, "Corrosion" includes such defects as metal loss, pitting and fracture which, if left unchecked, can progress to result in pipe failure. Downhole corrosion monitoring is particularly important in the operation and management of wells and oil, gas or water fields, not only to predict the useful life of the pipeline and well casing, in order to avoid failures during the operation , but also in the & ***. * & *. ** .., * * ^^^^ determination of the effectiveness of chemical additives with the intention of minimizing such corrosion. Although the methods currently used to monitor downhole corrosion vary, they all require the use of 5 wire lines to install and / or retrieve devices placed in predetermined positions or the run of exploitation tools. These prior art methods include wireline logging tools that are attached to the end of a wire or cable; samples placed and recovered by wire line; and programmable electronic probes placed and retrieved by wire line. In order to use any of these methods, the well must be taken out of service. Disabling the well in a regular schedule for corrosion monitoring is expensive, not only in terms charges for direct labor, but also give terms of loss of production and inputs. Additionally, flow disturbance due to the installation of intrusive devices in the well bore can result in loss of corrosion rate information. The E.P-A-0 837 217 describes transducers used in a portable well closing tool that moves up and down inside the pipe string. EU-A-5 533 572 describes an apparatus and method that uses a pair of contactors or related electrodes and meters and a power source to measure the current and voltage between two separate positions along the length of a string of pipe and relative changes in these measurements for pipe corrosion. Apparatus and methods that use ultrasound to measure wall thickness of pipe and to detect defects are known for pipe and casing installed in wells, but must be run by wire line and suffer the same limitations as all intrusion tools. Also, due to the imprecise placement of wireline tools from one inspection to another, it is not possible to obtain reliable data on the corrosion regime in situ. Another major limitation of existing ultrasonic wireline devices is the requirement that they need to be run in a tube filled with liquid in order to transmit information. This requirement limits its use in multi-phase and gas wells. It is therefore an object of this invention to provide an apparatus and method that allows corrosion monitoring of downwells without putting the wells out of service or disrupting the flow, and that can be used in all types of well service, is say, wells of water, oil, gas and / or multiple phases. It is another object of the invention to allow the corrosion monitoring information to be obtained and analyzed at any desired frequency, or even continuously. Another object of the invention is to enable corrosion monitoring information to be obtained from the time of the installation of the well pipe and / or well casing strings t? liiffin ?? i [^^^ faith; * • * - * *** **** *. * *. * *. *. * ,,. ,,. ^ ^, "" ^, *. ' *., »,.% * I I A to provide a baseline, and thereby identify the beginning of corrosion as well as its rate of progress in the section or sections of the pipeline being monitored. It is also an object of the invention to provide a economic and cost effective method and apparatus to monitor downhole onsite corrosion that will provide reliable information without resorting to wire lines and intrusion tooling tools and methods.

BRIEF DESCRIPTION OF THE INVENTION The above objects and additional benefits and advantages are realized from the apparatus and method of the invention which comprises providing a plurality of piezoelectric transducers which are attached to the metal surface of a casing section or well pipe in a predetermined and fixed arrangement. In the first preferred embodiment, the plurality of transducers forming a given fixed array are electrically connected by conductors to at least one microprocessor that is placed proximate to the transducer array.

The microprocessor is also electrically connected to a lead wire leading from the position of the descending hole of the boxing or piping section to a surface facility where there are means of power supply, computer controlled control and instrumentation, media processing and storage of information, and means of display, such as a printer and / or CRT monitor. In another preferred embodiment, a wireless system may be employed in which the microprocessors are electrically connected to the casing string or pipe which serves as the conductor for relieving energy and information signals between the surface instrumentation and the microprocessors. In a preferred embodiment, a reference block made of the same material as the pipe being monitored close to the corrosion monitoring transducer array is installed. He The reference block is isolated from any sources of corrosion. The reference block may preferably be in the form of a stepped wedge having a plurality of predetermined thicknesses corresponding, for example, to the original thickness of the wall of the pipe section being monitored, one or more intermediate lower thicknesses, the thinner section of the wedge corresponding to the minimum predetermined safety thickness of the casing tube wall or pipe that will allow the continuous operation of the well. The transducers are also attached to each of the surfaces that form the steps in the reference block, and these transducers are electrically connected to a microprocessor, which may be the same microprocessor associated with the fixed array of transducers, or to a separate microprocessor which in turn is connected by cable to the surface control facility , or alternatively directly to the boxing string or pipeline if you are using a wireless system. In a preferred embodiment of the invention, the fixed array of transducers, the reference block with transducers and the microprocessor, or associated microprocessors, are fixed in a short section of the connector tube that is used to join the standard lengths of boxing tubes. and / or well pipe. The use of short sections of connecting tube facilitates the assembly of the monitoring apparatus, and also its placement in the well gauge. Since the connectors are required in any case to join sections of pipe as the string proceeds in the bore of the well, additional time and labor is required to provide the ability to monitor periodic or essentially continuous corrosion at any desired number of vertical locations along the string of tubes. In the practicing the method of the invention, the principal additional steps required at the well head are the connection and securing of the conductor cable which is to transmit signals from the facility at the surface and to receive information from the microprocessor. However, in the practice of the modality that employs a wireless system, these additional steps are not required. In the practice of the method, a general purpose computer with appropriate software is provided to generate a signal to activate each microprocessor and the signal is transmitted via the conductor cable, or alternatively, using means of ^ ********** Í Í * * ^^^^ | i ** j¡ | g ^ ^^ _ ^ wireless transmission in which the pipe string serves as a conductor. Upon receiving the activation signal, each microprocessor activates its associated transducer and receives the information generated in relation to the condition of the cased string or pipe to which the transducer is attached, or in the case of the reference block, receives information of baseline or comparative from the block that is isolated from potential sources of corrosion. The microprocessor (s) in each location that is monitored then transmits information via the cable conductor or wireless transmission media to the surface installation. The information is received by computer-controlled control and instrumentation means, from which it can be transferred either directly to means of information storage, or first to information processing means and then to the storage medium. Once the information has been processed it is available for viewing either in printed form or visually displayed on a CRT monitor. Various other modalities and configurations of the apparatus and the The method of the invention will be apparent to those of ordinary skill in the art from the following detailed description of the invention.

BR EVE DESCR I PCI OF THE D ISSUES 25 Figure 1 is a schematic sectional illustration simplified from a typical well that produces liquid or gaseous hydrocarbons, water, or multi-phase fluids; Figure 2 is an enlarged segmented cross-sectional view of Figure 1; Figure 3 is a cross-sectional view of a well box segment illustrating a preferred embodiment of the invention; Figure 4 is a schematic electrical diagram illustrating a preferred embodiment of the invention shown in Figure 3; Figure 4A is a schematic electrical diagram showing a detail of an element of Figure 4; Figure 5 is a cross-sectional view of a well box segment illustrating another preferred embodiment of the invention; Figure 6 is a schematic electrical diagram illustrating another preferred embodiment for wireless data transmission; Figure 7 is a side elevational view of a typical reference block arrangement; Figure 7A is an end view of the block of Figure 20 7; and Figure 7B is a top plan view of the block of Figure 7.

DETAILED DESCRIPTION OF THE PREFERI DAS MODALITIES 25 As shown in the simplified illustration of Figure 1, gU ^ g gg ^ & i ^ i **. ** *** *. *, ** ********** .z * ** a well 10 producing reservoir fluid includes a string 2 sandwiched around a string 3 of pipe extending down into the earth to the deposit rock from which the reservoir fluids are extracted. Each of the strings comprises lengths of tube 4 connected by connectors (not shown). The tubes comprising the boxing string are lowered to the place as the well is being drilled and secured together by any of a variety of tube connectors. Then, the lengths of tube comprising the pipe string are lowered into the box to provide a conduit through which fluids are withdrawn from the tank from the tank. The spatial relationship of the lengths of your bo that comprise the casing and the pipeline is shown in Figure 2. In a preferred embodiment of the invention schematically illustrated in Figure 3, a short section of casing tube 20 is provided with a plurality of piezoelectric transducers 26 that are attached to the surface 22 of the outer casing in a fixed array. In an especially preferred embodiment, the fixed array comprises at least three longitudinally spaced rows and each row contains at least three transducers that are radially spaced around the circumference of the tube, i.e. at 120 ° intervals. The fixed arrangement of transducers 26 is electrically connected by conductors 27 to at least one *? I *** - i ^ ^ ¿a ^^ *** ^ *! ^ T ± ^ * J * = ^^^ * & ^? * ^ l. * ^ ** ^ * ^ ***. *? *1* ** -*? microprocessor 28. In a preferred embodiment, the one or more microprocessors are located in close proximity to the associated transducer array. With reference to the scheme of Figure 4, the lead wire 32 extends from a plurality of microprocessors 28 to a surface installation 80 consisting of a power supply 70 and associated computer-controlled control and instrumentation 72, storage and processing means 74. of data, and printing means 88 and display means 90 placed on the surface, preferably in a mobile or permanent installation. The means of control and instrumentation includes a general-purpose computer and software program to activate each individual microprocessor and each of its associated transducers, to receive the information from each of the microprocessors, and to later release the information either for storage or for processing. In an alternate preferred embodiment, the information received on the surface is derived from the surface control means via, v. g. , a telemetry unit or a ground line (not shown) for processing and storage at a remote well location. This modality is particularly adapted to monitor the condition of one or more wells in isolated areas or at great distances from the field service offices. According to well-known methods and procedures in ? - & ** - * ** + ** i * .-. * ^ ** fctffá ** 1 * ^ • * t - ^? ^ *** ^ **. * tut &28®L ** & In the prior art, the signals generated by the computer-controlled instrumentation and control means 72 are transmitted via the cables 32 to each of the microprocessors 28, which in turn are activated to transmit signals for the arrangement of transducers 26 associated with each microprocessor. The signals generated and received by the arranged transducers are returned to their associated microprocessor 28 for transmission to the means 74 for receiving, processing and storing data in the surface installation 80. The information can be processed before being stored in the memory device, or later. The processed information itself is classified and / or made available for transmission to a display device. The condition of the casing section or well pipe that is monitored is displayed in numerical and / or graphic terms on a computer monitor 90 and / or print 88, and the information is fed into a storage device 74 or information memory appropriate. In the further preferred embodiment of the invention shown in Figure 3, the associated transducer and microprocessor array are enclosed in a protective cover 40 secured to the outside of the tube, as by welds 42. The conductor 32 passes through gaskets or collar 43 fluid-tight placed on the cover 40, said cover is preferably made of a material that is the same as, or very similar to that from which the pipe or box string is made to which it is attached.

JM A.alU,. TO ? i am *** * ** In order to monitor the condition of the outer surface of a section of the pipe or casing, a second array of transducers 36 is fixed to the inner surface 44 of the protective cover 40 and joined by conductors appropriate to associated microprocessor 38, which in turn is electrically connected to the lead 32. Then, appropriate signals are received a and received from the outer array of transducers and the information is processed to display as described above in relation to the method and apparatus for monitoring the condition of a section of the interior of the pipe string or box. With reference to Figure 3, each down hole device preferably includes at least one reference block 60. As best shown in Figures 7, 7A and 7B, reference block 60 may be in the form of a stepped wedge, whose configuration and operation is described in more detail below. It will be understood from the foregoing description that the activation of the transducers may be in accordance with any desired program or frequency, or on an essentially continuous basis. Also, any number of separate transducer arrays can be inserted into the pipe and / or caisson strings as they are assembled and lowered into the well gauge. With reference to Figure 5, another preferred embodiment is shown where the transducer array is attached to a pipe joint 50 which is attached to the ends of individual lengths of pipe or casing to join them together. The outer surfaces of the ends of the pipe or casing tubes are provided with a tapered configuration 23 which corresponds to the internal tapered surface of the pipe joint 50. This connection junction 50 and tube end can be effected by threaded surfaces, or other means of the art. In this embodiment, the joint 50 is made of the same type and grade or type and similar degree of steel as the tube and is provided by a slot 52 for having the transducers and microprocessor (s) to minimize the overall outer diameter of the pipe joint. with attached cover. This modified bonding configuration 50 is designed to maximize the clearance between the pipe string and casing or between the casing string and the rock, to minimize the risk of damage to the transducer and microprocessor arrays during installation. According to the previously described embodiment, the transducers and the associated microprocessor that are attached to the modified joint 50 are provided with a protective cover 40 shown in Figure 5. The advantages of joining the transducer arrays 26 to monitor internal tube corrosion , and, optionally, the transducer arrangements 36 for monitoring the outer corrosion of the tube, for the modified tube joint 50 are several. Since pipe joints must be installed in any case, you do not need to install shorter pipe sections additional and the number of meetings are kept at a minimum, so there is a saving in time, labor and money. Standard tube fittings can be modified at low cost and installed using normal procedures and without special training of the work force. Most importantly, the intervals or separation between sections of the string to be monitored is easily determined during the installation of the pipe strings according to the final location of each of the monitoring points. For example, if the individual tube sections are of length "L" meters, and monitoring for corrosion conditions in the deepest portion of the well is going to be at 3L meters, then a modified joint 50 is used to join each third section of tube to the next as the string descends into the well. In a further preferred embodiment, the apparatus of the invention includes a reference block 60, such as that illustrated schematically in Figure 7. The reference block is made of the same material as, or a similar material from the pipe string or boxed It is supervised, and as indicated, their names will provide reference or comparative information in one or more thicknesses of material. The reference block is stepped and is provided with a plurality of transducers 62 fixed to its stepped surfaces and installed so as to be insulated from the source of corrosion. ^^^^^^^^ i i ^ • *** .- *** Áüi ****, ****** á? k L. j ¿B ** to Figure 7, stepped wedge reference block 60 is provided with transducers for three different thicknesses. The information received from each pair of transducers 62 'and 62"and 62'" corresponds to the signal passed through the metal sound, that is to say, unaffected by corrosion, of the respective thickness. Each pair of transducers 62 is connected to the microprocessor 64 by conductors 66. The microprocessor 64 is also connected by a lead 32 to the surface control and instrumentation, if a wireless system 10 is not being used. Since the reference block and its transducers will be subject to the same conditions, v. g. , of temperature and pressure, that the adjacent transducers attached to the pipe string being monitored, any variations in the local conditions that occur over time affecting the reference block 15 can be applied to the corrosion information as a line of base, or correction factor. In a preferred embodiment, the maximum thickness of the reference block, which corresponds to the transducer pair 62 '", is the same as the wall thickness of the tube being monitored.Thus, the ratio 20 between the information of the associated transducers and microprocessors In the case that there is an onset of corrosion, their progress can be estimated by comparing information obtained from the pairs 62 to the reference surfaces and tube, even before the string is placed in the borehole. 'and 62' block transducers * < *? $ »* At? * M * i > . . - .1 * .. * * ^, ^ * ^^. ^^^ .. É ^^^^, I-f f-JÉm fri reference. As illustrated in Figure 7, the thinnest portion of the block 60 can be established as the minimum tube thickness required or accepted for continuous operations, so that when the information corresponding to this thickness is received from the monitoring transducers , that section is identified for replacement. It will also be understood that cable 32 will extend from each monitoring location along the string to the surface, if a system is not being used. wireless. In a preferred embodiment, the lead wire 32 extends in a parallel circuit between the adjacent monitoring units 25, each unit having appropriate input / output sockets to electrically receive and secure the cables against displacement during the movement of the strings. The main conductor wire 32 is secured to the surface of the pipe by clamps, tie-downs or other means known in the art. The cable 32 is secured to prevent stretching and to protect the cable against mechanical wear and other damages. When required by local conditions, a pressure barrier for wellhead and an electrical safety barrier (not shown) and the cable is passed through these devices. The invention also contemplates the method for relieving signals and information by means of control of surface and the one or more hole microprocessors 28 descending via wireless transmission means, as schematically illustrated in Figure 6. In this embodiment, the cable 32 connecting the surface control means with the microprocessor (s) 28 is replaced by a transmitter / receiver 5 connected electrically to the pipe or casing of the well that serves as the signal path. The relationship of these elements is shown schematically in the block diagram of Figure 6, where a plurality of microprocessors 28 and associated transducer arrays 26 are attached, for example, to the pipe string 30. The power supply 70, control and instrumentation means 72 and means 74 for storing and processing data are linked by appropriate electrical cables. In addition, the transmitter / receiver 74 'is electrically connected to the control instrumentation 72 and 15 to the string 30 that contains the transducer arrays 26. Each microprocessor 28 is programmed or constructed to provide a unique identification signal so that its location in the string, and therefore its depth, is known. The microprocessor may also be programmed to identify each of its associated transducers for recording and displaying information purposes. Each microprocessor associated with a reference block 60 is programmed or constructed to uniquely identify each transducer 62, v. g. , 62 ', 62"and 62'" of Figure 7, and the information derived from each such position in the stepped wedge.

In practicing the method, a signal is transmitted from the surface control means to activate one or more downhole processors 28, and that array of associated microprocessor transducers, at one or more specific locations. The information received by each microprocessor of its associated array of transducers is transmitted back to the means of receiving and processing information on the surface of the earth, together with that signal (s) of unique identification of the microprocessor. The information associated with each microprocessor may be either directly fed or processed first and then fed to the data storage means in a location corresponding to each of the unique identification code (s) of the microprocessor. The information can be retrieved for further processing, or for transmission to the information viewing medium, v. g. , a CRT monitor or a printer that can produce a hard copy of the information in numeric and / or graphic form. It will be understood that various modifications can be made to the modalities described above. Therefore, the description should not be taken as limiting, but merely to exemplify preferred modalities. Those of ordinary skill in the art will devise other modifications within the scope of the following claims.

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Claims (25)

1. R E IVI ND ICATIONS 1. An apparatus for supervising corrosion in a down hole to determine the condition of a section of a well pipe string or a well casing string, in a working well without putting the well out of service, the apparatus comprising: ( a) a plurality of piezoelectric transducers arranged in a fixed array, spaced longitudinally and axially therebetween, and fixed around the circumference of the surface 10 outside of the pipe string section or the inside surface of the box string to be monitored; (b) a microprocessor electrically connected to the transducers to activate the transducers and to receive and transmit signals produced by the transducers, 15 (c) a source of electrical energy and conduction means that extend from the power source to the microprocessor; (d) control and instrumentation means for activating the microprocessor and for receiving, recording and processing the information output signals of the microprocessor; 20 (e) display means in association with the control and instrumentation means to display information relative to the corrosion rate and location of defects in the section of the pipe string or casing.
2. 2. The apparatus of claim 1 wherein the piezoelectric transducer comprises a material selected from the group that . *** ^ ************; *? ******,. .i? * ^ * kÉ ** .. .i ^ ***** .. * ^^. ^^^.? ** ^ *****! ***** .. ^^ ** ^^^ g, consists of quartz, ceramics, polymers and hybrids formed from quartz, ceramics and polymers.
3. The apparatus of claim 1 or 2 wherein a plurality of sections of a casing string or casing string or both are monitored for corrosion regime.
4. The apparatus of any of claims 1 to 3 wherein the fixed array of transducers comprises at least three longitudinally separated transducers.
5. The apparatus of any one of claims 1 to 3 wherein the fixed array of transducers comprises a plurality of longitudinally spaced transducers extending 360 ° around the circumference of the pipe string or casing.
6. The apparatus of any of claims 1 to 5 wherein the transducers are attached to a section of the pipe string or the box that is intermediate to the joint connectors.
7. The apparatus of any of claims 1 to 6 in which the transducers are attached to a joint connector, said joint connector is made of a material that is the same as or similar to the material of the pipe string or boxed associated 8.
8. The apparatus of claim 7 wherein the joint connector is provided with a groove extending around its circumference, and the transducers are attached to the bottom of the joint. groove.
9. The apparatus of any of claims 1 to 8 further comprising at least one reference block that is insulated from the source of corrosion and a plurality of transducers 5 fixed to the reference block.
10. 10. The apparatus of claim 9 wherein the reference block is made of a material that is the same or similar to the associated casing material or pipe. eleven .
11. The apparatus of claim 9 or 10 in which the reference block 10 has sections of different thicknesses and at least two transducers are fixed to each of said sections.
12. 12. The apparatus of any of claims 1 to 11 in which the transducers are surrounded by a cover 15 protective.
13. The apparatus of claim 12 wherein the protective cover is made of a material that is the same as or similar to the material of the section of the boxing string or pipe to which it is attached.
14. 14. The apparatus of claim 12 or 13 in which a fixed array of transducers is attached to the inner surface of the protective cover.
15. The apparatus of any of claims 1 to 14 in which the microprocessor attached to the transducer array is 25 enclosed by the protective cover.
16. 16. The apparatus of any of claims 1 to 15 in which the microprocessor is placed proximate to the transducers to which it is connected.
17. The apparatus of any of claims 1 to 16 wherein the fixed array of transducers is attached to a short section of casing or casing tube for assembly into a string.
18. The apparatus of any of claims 1 to 17 wherein the source of electrical energy is selected from the group consisting of batteries, a main DC power supply, and thermoelectric generators.
19. 19. The apparatus of any of claims 1 to 18 wherein the source of energy is placed on the surface proximate to the boxed pipe section p to be monitored.
20. 20. A method for monitoring downhole corrosion of at least one section of a pipe string or well boxing string, said method comprising the steps of: (a) joining a plurality of piezoelectric transducers in a first fixed arrangement longitudinally and radially spaced apart on the surface of at least one section of a casing string or casing string, or both; (b) electrically connecting a programmed microprocessor to the first fixed array of transducers and to an electrical power source; ** * TO * **!***. . and ... * **** * ^ *** ^ ** ^ *** ^ * k * \ *? ****? Í ** £ * »t. - * bi3 J > * A j (c) provide control means, data receivers, processing, display and storage to transmit electrical signals to and receive electrical signals from the microprocessor; (d) transmitting signals to the microprocessor to activate the transducers; (e) receiving signals from the transducers and transmitting the signals via the microprocessor to the data receiving and processing means; (f) process the data related to the presence of corrosion and defects in the section of the string that is monitored and visualize the information processed in the display medium. twenty-one .
21. The method of claim 20 in which signals for the microprocessor are transmitted intermittently.
22. The method of claim 20 or 21 comprising the further steps of: providing a reference block made of a material that is the same as or similar to the string material being monitored; fixing the reference block close to the first fixed array of transducers in isolated relation to the string; obtain information about the condition of the reference block of the transducers and microprocessors associated with the block; and compare the relative information with the condition of the reference block with the information relative to the section of the string that is supervises.
23. The method of any of claims 20 to 22 wherein a plurality of arrays of electrically connected transducers and microprocessors are attached to a plurality of separate sections of the pipe strings or casing or both pipe strings and casing.
24. The method of any of claims 20 to 23 which comprises the additional steps of: providing a protective cover made of a material that is the same as or similar to the material of the section of the string being monitored; install the cover to enclose the fixed array of transducers on the outer surface of the section; joining a plurality of transducers and a microprocessor associated with the interior of the protective cover to form a second fixed array; and obtaining information from the first and second fixed arrays, to thereby determine the internal and external comparative condition of the surfaces of the section being monitored with respect to the reference block.
25. 25. The method of any of claims 20 to 24 wherein at least one section of pipe string or well casing is in an oil well producing. i * l *, L 1k? á *. úi ** 1 * 1 * 1. ***** *. *. . ^. J ^ ^^ j ^^^^^^ j ^^^ g ^^^^^^^^^ a ^^^^^^. A * - * - * - i