Patent Publication Number: US-9422793-B2

Title: Erosion tracer and monitoring system and methodology

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present document is based on and claims priority to U.S. Provisional Application Ser. No. 61/394,590, filed Oct. 19, 2010, incorporated herein by reference. 
    
    
     BACKGROUND 
     In a variety of well applications, particulates in fluid flows can cause erosion of downhole components, such as erosion of sand screens and other completion hardware. The potential for erosion is a factor in determining proper control over fluid flow parameters. When bringing on production of a sand prone hydrocarbon producing well, for example, various determinations are made with respect to the speed at which production can be ramped up without breaching the filter media. Determinations also are made with respect to the optimum flow rate of production fluids to avoid causing erosion to the filter media or to other completion hardware. However, determining desirable flow rates can be difficult and the optimum or otherwise desired flow rate can change over time. 
     SUMMARY 
     In general, the present disclosure provides a system and methodology for detecting and monitoring erosion in, for example, a downhole environment. A tracer element is located in a component such that sufficient erosion of the component due to fluid flow exposes the tracer element. A monitoring system is disposed for cooperation with the tracer element such that exposure of the tracer element is detected by the monitoring system. The monitoring system outputs appropriate data indicative of the erosion to enable adjustments to the fluid flow. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Certain embodiments will hereafter be described with reference to the accompanying drawings, wherein like reference numerals denote like elements. It should be understood, however, that the accompanying figures illustrate only the various implementations described herein and are not meant to limit the scope of various technologies described herein, and: 
         FIG. 1  is a schematic illustration of an example of a well system comprising a component having a tracer element, according to an embodiment of the disclosure; 
         FIG. 2  is a schematic illustration of a production well system comprising a tracer element, according to an embodiment of the disclosure; 
         FIG. 3  is a schematic illustration of a well component in the form of a sand screen incorporating a tracer element, according to an embodiment of the disclosure; 
         FIG. 4  is a cross-sectional view taken generally along line  4 - 4  of  FIG. 3 , according to an embodiment of the disclosure; 
         FIG. 5  is a schematic illustration of a component or a plurality of components having a plurality of tracer elements, according to an embodiment of the disclosure; and 
         FIG. 6  is a schematic illustration of an injection well system comprising a tracer element, according to an embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, numerous details are set forth to provide an understanding of some illustrative embodiments of the present disclosure. However, it will be understood by those of ordinary skill in the art that the system and/or methodology may be practiced without these details and that numerous variations or modifications from the described embodiments may be possible. 
     The disclosure herein generally relates to a system and methodology which facilitate detection of erosion due to flowing fluids, e.g. detection of well component erosion due to flowing fluids in a well. According to an embodiment of the disclosure, a tracer element is employed in an erosion tracer and monitoring system to detect erosion at discrete and/or relative well interval locations, e.g. production well interval locations. The system and methodology also may be employed to monitor the erosion and to provide feedback to prevent further material loss. If a predetermined degree of erosion occurs, the well production can be adjusted to a lower rate; the well may be shut off at discrete intervals of production; the well production can be deferred to a later date after manual intervention of the wellbore; and/or the amount and rate of erosion may be continually tracked over time. 
     In injection well applications, the system and methodology also may be employed to detect and monitor erosion. Depending on the type of tracer element employed, an erosion monitor may be located downstream from a tracer element and telemetry methods may be employed to transmit erosion data from the erosion monitor to a surface location. Upon detection of a predetermined degree of erosion occurring at a discreet or relative injection interval in a filter media or other component, the injection rate can be reduced or otherwise adjusted. In some applications, the well may be shut in and subjected to intervention operations with corresponding well treatments. The detection of erosion also may lead to injection profile modification such that the injection well is operated within allowable operating erosion conditions. The data provided by the erosion monitoring system also can be used to increase the injection rate (or production rate) to a safe threshold of acceptable erosion during operation of the injection or production well. 
     By way of example, an embodiment of the disclosure comprises an erosion tracer and monitoring system designed to determine where and when sand screen erosion occurs downhole. An embodiment of the erosion/tracer element may be a commercially viable continuous length of metal with embedded tracer such that the tracer is activated when sufficient erosion of the material, e.g. metal, occurs on the face of the sand screen or other completion component located within the wellbore. The tracer element or elements can be located at a single discreet location or throughout a completion interval, e.g. along a sand screen interval, to create a vigilant system for monitoring localized erosion and/or to create a passive system for monitoring general erosion along a well interval. 
     In some well applications, monitoring of erosion may take place at a wellhead in a manner which enables the well to be opened for increased fluid flow at a desired, e.g. optimized, production rate or injection rate. Depending on the data obtained and output by the monitoring system, the well also may be choked back or shut in to determine an appropriate intervention prior to incurring damage to filter media or other completion hardware. The data obtained from the erosion monitoring system also can be used to selectively and/or automatically operate the well at a steady state without erosion or with controlled erosion while continually monitoring future erosion of the completion component. If the well application is a subsea application, the erosion monitor may be located at, for example, the seafloor. The feedback and control capabilities of the monitoring system also may be used for local flow rate adjustment; and/or erosion data may be transmitted to a remote location for further evaluation. 
     Various embodiments of the disclosure comprise a system and methodology for detecting erosion along a producing interval or an injecting interval of a well with discrete or relative location/position identification. The system and methodology also enable monitoring of erosion at the location while providing feedback regarding the specific erosion or lack of erosion. The feedback may be provided to a desired location, such as a surface location, and/or used to automatically change the rate of fluid flow by adjusting a flow control device. In some applications, an erosion monitor may be located downhole and the erosion data may be transmitted uphole to a surface display device and/or used for automatically controlling, e.g. optimizing, the fluid flow rate of the production or injection well. In some applications, well production or injection may be adjusted such that erosion of completion components is within an allowable erosion operating window. The fluid flow rate also may be reduced to defer material loss, e.g. metal loss, with respect to filter media or other completion components. The system and methodology also may be employed to detect high velocity flow areas in production or injection intervals. Many types of tracer elements may be used to indicate erosion of components, including erosion tag elements which are released and carried by the fluid flow to an erosion monitor able to detect the material as indicative of erosion. 
     Referring generally to  FIG. 1 , an example of one type of application utilizing a plurality of downhole completion components and corresponding tracer elements is illustrated. The example is provided to facilitate explanation and it should be understood that a variety of well completion systems and other well or non-well related systems may utilize the methodology described herein. The downhole completion components and corresponding tracer elements may be located at a variety of positions and in varying numbers along the well completion or other tubular structure. 
     In  FIG. 1 , an embodiment of a well system  20  is illustrated as comprising a downhole well completion  22  deployed in a wellbore  24  and monitored by an erosion monitoring and control system  25 . The well completion  22  may be part of a tubing string or tubular structure  26 , such as production tubing or well casing, although the tubular structure  26  also may comprise many other types of well strings, tubing and/or tubular devices. Additionally, the well completion  22  may include a variety of components, depending in part on the specific application, geological characteristics, and well type. For example, the well completion  22  may comprise filter media in the form of a sand screen or sand screens as well as a variety of other completion components. 
     In the example of  FIG. 1 , the wellbore  24  is illustrated as generally vertical with the downhole well completion  22  deployed along the generally vertical wellbore. However, various well completions  22  and other embodiments of downhole equipment may be used in the well system  20  and may be deployed in other types of wellbores, including deviated, e.g. horizontal, single bore, multilateral, cased, and uncased (open bore) wellbores. 
     In the example illustrated, wellbore  24  extends down through a subterranean formation  28  having at least one and often a plurality of well zones  30 . The well completion  22  comprises a plurality of components  32 , such as sand screens. However, components  32  may comprise additional and/or alternate types of well tools and components. By way of example, the well components  32  may be associated with tracer elements  34  of the erosion monitoring and control system  25 . The tracer elements  34  are designed to provide an indication of erosion upon the occurrence of a sufficient amount of erosion with respect to a corresponding well component  32 . In some applications, a single tracer element  34  may be deployed to provide an indication of erosion at a specific discrete location or to provide an indication of general erosion along a well interval, e.g. along an extended component such as a sand screen. In other applications, a plurality of tracer elements  34 , as illustrated, may be employed to detect erosion at a plurality of corresponding components  32  or at a plurality of locations along a single, elongated component  32 . The tracer elements  34  also may be designed to provide a unique indicator relative to the other tracer elements to enable monitoring of erosion at specific components and/or at specific locations along the wellbore  24 . 
     The tracer elements  34  cooperate with an erosion monitor  36  designed to monitor the individual tracer element or plurality of tracer elements  34 . For example, the erosion monitor  36  may be designed to detect material released from the tracer element  34  upon sufficient erosion of well component material to expose the tracer element  34 . In other embodiments, exposure of the tracer element  34  to flowing well fluid causes the tracer element to provide another type of signal, e.g. electrical, which is detected by the erosion monitor  36 . Regardless of the specific type of tracer element  34 , data from the tracer element is relayed to the erosion monitor  36  which may be part of a control system  38  or which may transmit the data to control system  38 . 
     Depending on the type of well operation, the erosion monitor  36  may be positioned at a variety of locations. For example, the erosion monitor  36  may be located in or near a wellhead  40  located at a surface  42 , such as an earth surface or a seabed. In some injection applications, the erosion monitor  36  may be located downhole at a location downstream from the tracer elements  34 . (See dashed lines in  FIG. 1 ). When the erosion monitor  36  is located downhole, a suitable telemetry system  44 , e.g. a wired or wireless telemetry system, may be employed to relay data uphole to control system  38  at, for example, surface location  42 . The telemetry system  44  may be designed to operate independently or it may be combined with telemetry systems used to convey data regarding other well parameters, such as pressure, temperature and flow rate. 
     Based on the data provided by erosion monitor  36 , the production/injection fluid flow rate may be maintained or adjusted to optimize or otherwise change the flow rate. For example, the flow rate may be reduced to slow or prevent erosion, or the flow rate may be increased to enhance production or injection while maintaining the rate of erosion within a desirable operating window. In some applications, the data from erosion monitor  36  is relayed to control system  38  which is used to display and/or to automatically control the fluid flow rate. For example, the control system  38  may be used to automatically adjust a flow control device  46  or a plurality of flow control devices  46 . The flow control device  46  may be located at the wellhead  40  in some operations, however other operations benefit from one or more flow control devices  46  positioned at desired downhole locations. Additionally, control system  38  may be combined with the erosion monitor or monitors  36  at a surface location or add a downhole location to automatically control the flow control devices  46  according to the degree of erosion or lack of erosion indicated by tracer elements  34 . 
     The erosion/tracer element  34  may have a variety of forms and may be positioned in a variety of locations. For example, the tracer element  34  may be embedded in individual well components  32  such that erosion of the well component  32  to a sufficient degree exposes the tracer element  34  and signals erosion monitor  36 . In some applications, the tracer element  34  may comprise a sacrificial element, such as a continuous length of wire, rod or other element of suitable geometry. The sacrificial element may have a similar metallurgy and yield strength compared to the well component, e.g. screen filter media or completion component. Exposure of the tracer element  34  during erosion releases tracer element material which is flowed in the fluid stream and detected by the erosion monitor  36  at the wellhead  40  or at another suitable location. With multiple tracer elements  34 , each tracer element  34  may have a unique identification or signature corresponding to the specific well component and/or interval position to provide an indication as to the specific location incurring erosion. The tracer element  34  and erosion monitor  36  also may be designed to determine the rate of erosion, e.g. the rate of metal loss of the well component  32 . For example, the erosion monitor system  36  may be designed to monitor the amount of tracer element  34  released into the fluid stream due to the erosion to determine the extent of the erosion. It should be noted that the tracer elements  34  may comprise a variety of materials and configurations, including electrical elements, light/optical elements, sensors, and various other elements able to provide an indication of the erosion. 
     The location of erosion/tracer element  34  with respect to the well component  32  can vary depending on the design and parameters of the monitoring system. For example, tracer elements  34  may be located within, on, and/or between sand screen filter media features. With wire wrapped filter media, for example, the tracer elements  34  may be located in the filter media, in the inner drainage layer, in the base pipe, and/or in various combinations of these features. Similarly, with wire mesh filter media, the tracer elements  34  may be located in the shroud, in the outer drainage layer, in the filter media, in the inner drainage layer, in the base pipe, and/or in various combinations of these features. With other types of filter media, the tracer elements may be located within individual features or various combinations of features, including shrouds, filter media, and base pipes. Alternate path type sand screens may convey the tracer element on or within the outer shroud or on or within the alternate path transport or packing tubes. In some downhole completions, the tracer element  34  may be conveyed on/within hydraulic lines, electrical lines, or other control cables or conduits. The tracer element  34  also may be conveyed on/within casing, production tubing, blast joints, perforated pipe, production liners, or other completion equipment. 
     Tracer elements  34  may comprise many types of elements embedded in the material subject to erosion. For example, the tracer elements  34  may comprise tracer tags  48  formed of unique combinations of natural or man-made elements embedded in the sacrificial erosion element or incorporated within completion components. The tracer tags  48  are formed of material released due to erosion and are generally different from naturally occurring elements found in the reservoir, wellbore, completion components, well treatment fluids, or produced/injected fluids. Examples of sources of unique tracer tags  48  comprise unique elements that may be embedded to provide identification of wellbore depth and/or interval position upon sufficient erosion. The tracer tags  48  may comprise various radioactive isotopes, chemicals, or other materials that can be carried in the fluid flow to the erosion monitor  36 . The tracer tags  48  also may comprise material particles with specific characteristics, including characteristics related to: light refraction, geometric shape, mass, physical size, unique embedded codes, electrical resistance, length-width-height-diameter-circumference-perimeter-surface area-volume characteristics, mathematical combinations of these characteristics, e.g. specific ratios, surface roughness, pressure or light pulses, and/or unique color characteristics. Other methods for detecting the release of unique tracer tags  48  include the use of scientific methods for differentiation related to human-type senses, such as sight, smell, touch (feel), hearing (acoustic waves), taste, or various combinations thereof. 
     However, the tracer elements  34  may comprise a variety of other types of erosion indicators. For example, the tracer elements  34  may comprise sensor materials which output an appropriate signal, such as a radio, electrical, light, acoustic, pressure and/or sonic signal through an appropriate telemetry system  44  to erosion monitor  36 . By way of example, the tracer element  34  may comprise an electrical element that undergoes a characteristic change, e.g. a change in resistance, when exposed to a flowing fluid in the well. This change can then be relayed to the erosion monitor  36  as indicative of eroding material at the specific well component  32 . Regardless of the type of tracer elements  34  employed, position identifications may be made at discrete locations or relative to another position. Additionally, the system  25  may be employed for erosion monitoring and control regardless of wellbore orientation, deviation, completion type, or form of hydrocarbon production or fluid ejection. The erosion monitoring and control system  25  also may comprise many types of components, e.g. tracer elements  34 , erosion monitor  36 , control system  38 , flow control devices  46 , and other components as desired for a specific application. 
     Referring generally to  FIG. 2 , an embodiment of system  20  is illustrated as comprising a production system in which well fluid is produced up through tubing  26 . In this embodiment, sufficient erosion of the well screen or other completion component  32  releases tracer tags  48  which flow upwardly with the well fluid as indicated by arrow  50  for detection and monitoring by erosion monitor  36 . The erosion monitor  36  is designed to output data regarding erosion and erosion location (based on the unique characteristics of the tracer tags  48 ) to control system  38 . The control system  38  may be used to process and display erosion data and/or to automatically control one or more flow control devices  46 . In the example illustrated, flow control device  46  is automatically controlled and comprises a choke  52  positioned along tubing  26  at a surface location  42 . 
     By way of example, the well component  32  may comprise a sand screen component  54 , as illustrated in  FIGS. 3 and 4 . In this example, sand screen  54  comprises a base pipe  56 , a shroud  58 , and a filter media  60  disposed between the base pipe  56  and the shroud  58 . Production fluid flows from the surrounding formation  28 , into sand screen  54 , and along an interior of the sand screen  54 , as indicated by arrows  62 . The inflowing well fluid often contains particulates which can erode components of the sand screen, such as the base pipe  56 , filter media  60 , and/or shroud  58 . Accordingly, tracer elements  34  may be positioned on or within the base pipe  56 , the filter media  60 , and/or the shroud  58 , as best illustrated in  FIG. 4 . In some embodiments, the tracer elements  34  are embedded within the material used to form the sand screen components, such that erosion of the material releases tracer tags  48  for detection by erosion monitor  36 . 
     With relatively long well components  32 , such as sand screens  54  extending over substantial regions of formation  28 , the tracer elements  34  may be positioned at various sections along the elongate component  32 , as illustrated in  FIG. 5 . Each tracer element  34  may be designed to release unique tracer tags  48  upon sufficient erosion to provide an indication with respect to the specific location or the general interval of the well component  32  incurring the detrimental erosion. The released tracer tags  48  are detected and monitored by erosion monitor  36  to enable adjustment, if necessary, to the flow rate. In some applications, a plurality of flow control devices  46  may be independently adjusted based on the erosion data obtained by erosion monitor  36  to control the flow rate from or to specific well zones  30 . 
     As described above, the erosion monitoring and control system  25  also may be used for injection well applications, as illustrated schematically in  FIG. 6 . In this embodiment, sufficient erosion of the sand screen or other injection well component  32  releases tracer tags  48  which flow downwardly with the injection fluid as indicated by arrow  64  for detection and monitoring by erosion monitor  36 . The erosion monitor  36  is again designed to output data regarding erosion and erosion location (based on the unique characteristics of the tracer tags  48 ) to control system  38 . The control system  38  may be used to process and display erosion data and/or to automatically control one or more flow control devices  46 . In the example illustrated, flow control device  46  is automatically controlled and is positioned along tubing  26  at a surface location  42  to increase or decrease the rate of injection fluid flow based on the erosion data obtained and transmitted by erosion monitor  36 . 
     The system and methodology for monitoring and controlling erosion may be employed in non-well related applications which are potentially subjected to erosive fluid flow along a tubular structure. Similarly, the system and methodology may be employed in many types of well applications, including a variety of production and injection applications. The tracer elements may be positioned in many types of sand screens and sand screen components as well as in a variety of other completion components to provide erosion data at discrete locations or along substantial well intervals. The tracer elements also may comprise many types of tracer materials attached to and/or embedded in materials used to form various well components. The number and arrangement of tracer elements positioned along the tubular structure also can vary substantially from one type of application to another. Additionally, the design of erosion monitoring system  36  can vary depending on the type tracer element  34 /tracer material  48  being monitored. 
     The feedback provided by the tracer elements and erosion monitor may be used to optimize or otherwise adjust production or injection fluid flows to improve results. Depending on the feedback obtained via data supplied by the tracer elements and erosion monitor, the control system may be operated to adjust or the control system may be programmed to automatically adjust flow rates through the entire well or along specific zones within the well. For example, the feedback may be used to maintain operation of the well at a steady state, to increase the flow rate, to decrease the flow rate, or to shut off the fluid flow. In some applications, the fluid flow may be shut off temporarily to enable modification of the production/injection profile, to enable well interventions, and/or to isolate a portion or portions of the production/injection interval. 
     Although only a few embodiments of the system and methodology have been described in detail above, those of ordinary skill in the art will readily appreciate that many modifications are possible without materially departing from the teachings of this disclosure. Accordingly, such modifications are intended to be included within the scope of this disclosure as defined in the claims.