Patent Publication Number: US-2022235648-A1

Title: Gravel pack sand out detection/stationary gravel pack monitoring

Description:
BACKGROUND 
     One method for preventing the production of particulate to the surface during the production of hydrocarbons from a well is gravel packing the well adjacent a production zone. For a gravel pack completion, a completion string including a packer, a circulation valve, a fluid loss control device and one or more gravel-pack screens can be lowered into the wellbore to a position proximate the desired production interval. An inner service tool string can then be positioned within the completion string and a fluid slurry including a liquid carrier and a particulate is pumped through the circulation valve into the well annulus formed between the gravel-pack screens and the perforated well casing or open-hole production zone. 
     The liquid carrier either flows into the formation or returns to the surface by flowing through the gravel-pack screens or both. In either case, the particulate is deposited around the gravel-pack screens to form a gravel pack, which is highly permeable to the flow of hydrocarbon fluids but blocks the flow of the particulate carried in the hydrocarbon fluids. As such, gravel packs can successfully prevent the problems associated with the production of particulates from the formation. 
     SUMMARY 
     In one aspect, the disclosure provides a packing monitor for use in a wellbore. In one example the packing monitor includes: (1) a packing detector configured to, when stationary within the wellbore, obtain measurements indicating presence of a particulate in an annulus of the wellbore at different positions along a length of a screen, and (2) a packing controller configured to determine, based on the measurements, a status of the particulate in the annulus at the different positions. 
     In another aspect, the disclosure provides a method of gravel packing in a wellbore. In one example, the method includes: (1) pumping a fluid slurry into an annulus of the wellbore, wherein the annulus is partially defined by a screen and the fluid slurry includes a particulate, (2) obtaining stationary measurements indicating presence of the particulate in the annulus at different positions along a length of the screen, and (3) determining, based on the stationary measurements, a status of the particulate in the annulus at the different positions. 
     In yet another aspect, the disclosure provides a gravel packing system for a wellbore. In one example, the gravel packing system includes: (1) a screen, and (2) a packing monitor configured to determine, based on stationary axial measurements obtained during gravel packing, a status of a particulate at different positions along a length of the screen. 
    
    
     
       BRIEF DESCRIPTION 
       Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  illustrates a diagram of an example well system constructed according to the principles of the disclosure; 
         FIG. 2  illustrates a diagram of an example of a gravel packing system constructed according to the principles of the disclosure; 
         FIG. 3  illustrates a diagram of another example of a gravel packing system constructed according to the principles of the disclosure; 
         FIG. 4  illustrates a plot that shows an example of a status that can be generated by a packing monitor constructed according to the principles of the disclosure; 
         FIG. 5  illustrates a diagram of an example of a portion of a wellbore having two production zones that are gravel packed using a gravel packing system constructed according to the principles of the disclosure; 
         FIG. 6  illustrates a plot that shows another example of a status that can be generated by a packing monitor constructed according to the principles of the disclosure; 
         FIG. 7  illustrates a plot that shows yet another example of a status that can be generated by a packing monitor constructed according to the principles of the disclosure; 
         FIG. 8  illustrates a flow diagram of an example of a method of gravel packing a portion of a wellbore carried out according to the principles of the disclosure; and 
         FIG. 9  illustrates a block diagram of an example of a packing controller constructed according to the principles of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     The inner service tool string can be used to isolate the production zones and reverse out the excess particulate when screen-out is detected at the gravel-pack screens (hereinafter screens). Screen-out occurs when the particulate being pumped down the inner service tool string has completely filled the available space of the well annulus formed between the screens and the perforated well casing or open-hole production zone. At this point, a pressure spike is typically observed, pumping is stopped, and excess particulate is reversed out of the wellbore. Unfortunately, screen-out is not always accurately calculated or detected. If pumping continues for a period of time after screen-out, the inner service tool string can become stuck downhole. 
     In addition to detecting screen-out, determining the quality of the gravel pack is also important. Typically the existing tools or methods used to evaluate the quality of a gravel pack and determine if voids exist require the use of wireline or manipulation of the inner service tool string at the surface. Often these methods provide post-packing analysis that occurs after the inner service tool string is removed from the wellbore. If a void is detected, the inner service tool string is run in the wellbore again to top-off the packing. As such, multiple trips into and out of the wellbore can be required to gravel pack the different production zones of the wellbore. 
     The disclosure provides a packing monitor, method, and gravel pack system for real-time monitoring of a particulate for improved gravel packing. Via the real-time monitoring, the quality of the gravel pack can be detected in real-time. Accordingly, a top-off procedure can be performed without additional tripping of the inner service tool string. Detecting when the gravel pack is approaching screen-out can also be determined in real-time. Detecting when screen-out is approaching allows the operator to prepare to stop pumping in case of miscalculations or early screen-out. As the progress of the gravel pack operation can be tracked in real time, the risk of having the inner service tool string being stuck downhole is significantly reduced. 
     The packing monitor can also be used to automatically open and close valves downhole during gravel packing. The valves can be part of a completion string within the wellbore. By operating the valves using the packing monitor, the inner service tool string could be simplified or eliminated completely, which would be a significant cost savings to those in the oil and gas industry. 
     The disclosed packing monitor can be strategically placed within a gravel-pack system to detect screen-out in real time. The packing monitor includes a packing detector configured to, when stationary within the wellbore, obtain measurements indicating presence of a particulate in an annulus of the wellbore at different positions along a length of a screen. The measurements indicating the particulate presence correspond to non-contacting emissions from the particulate. The measurements can reflect detection of an energy signature of the particulate, such as radiation or magnetic permeability. 
     The measurements obtained by the packing detector can be radiation measurements or magnetic permeability measurements. As such, the packing detector can be a group of radiation sensors, such as an array of sensors, that detect a radioactive tracer placed within a particulate, the inherent radioactivity of a particulate, or a combination of both. The radiation sensors can be distributed with a known spacing along a length that corresponds to a screen. For example, the sensors can be an array of radiation sensors spaced approximately six inches to one foot apart that corresponds to a length of a screen. More or fewer sensors may be utilized depending on the level of granularity needed. The radiation sensors may be, for example, a photodiode or Geiger Muller tube (a memory gamma sensor). The detected ionizing radiation can be alpha particles, beta particles, or gamma rays. As such, the packing detector can be a gamma radiation detector can measure over a given length. The packing detector can be a group of magnetic permeability sensors, such as an array of such sensors. A magnetic permeability sensor can be, for example, a Hall sensor or a magnetoresistive sensor, such as a giant magnetoresistive (GMR) sensor, and may include a source of magnetic flux such as a permanent magnet or an electromagnet. If placed at the top of the zone being serviced, the packing detector can detect the presence of the particulate as it fills the annulus. If placed at other positions in the zone, then the progression of the particulate within the zone can be tracked. Each sensor can be communicably coupled together to a packing controller which allows for individual access to each sensor in order to determine a status of the gravel packing process. For example, a gamma plot can be created based on the individual measurements from the sensors. 
     Regardless the placement, the packing detector is configured to obtain stationary axial measurements, which are multiple measurements obtained along a length by a device that is stationary with respect to the length. For example, a packing detector as disclosed herein can obtain measurements in a vertical wellbore without moving the packing detector up or down in the wellbore. The stationary axial measurements can be simultaneously obtained by multiple sensors that are located to correspond to identified positions, such as positions along the length of a screen. 
     The packing detector is communicatively coupled to a packing controller of the packing monitor. The packing controller is configured to determine, based on the measurements from the packing detector, a status of the particulate in the annulus at different positions along the length of the screen. The packing controller can be integrated with the packing detector in a single device or can be located distal from the packing detector. A single packing controller can be configured to operate with more than one group of sensors. For example, a packing controller can be used with an array of sensors from two different zones. As such, the packing controller, or at least a portion thereof, can be located at the surface or at another downhole location instead of integrated with the packing detector. Accordingly, the status can be determined downhole and sent to the surface or the measurements can be sent to another location, such as the surface or another downhole controller or computing device, and the status determined thereat. The status or measurements can be communicated using a communication system typically employed in a wellbore environment, including an acoustic system, fluid system, optical system, wired system, wireless system, or a combination of the various system. A wireless acoustic system employing repeaters can be used for at least a part of the communication. Regardless where determined, the status can be used for the packing operation. 
     A computing device, such as at the surface, can automatically employ the status to modify a gravel-packing operation, such as changing an injection pressure, return pressure, flow rate, particulate concentration, alternative flow pathways, etc. A human operator can also manually modify the packing operation based on the status. For example, the status can be in the form of a plot, such as a gamma plot, that represents the particulate along the length of the screen. A human operator can view the plot on a display or a print out and manually modify the gravel-packing operation based on the plot.  FIGS. 4 and 6-7  provide examples of plots generated by a packet controller that show the status. The packing controller can also automatically operate valves or sleeves of a completion assembly based on the status to modify a packing operation downhole. As such, the packing controller can automatically initiate downhole actions without transmitting the measurements or status up hole. Accordingly, an inner working tool string may not be needed for gravel packing. 
       FIG. 1  illustrates a diagram of an example well system  100  constructed according to the principles of the disclosure. The well system  100  includes a semi-submersible platform  110  positioned over a submerged hydrocarbon formation  120 , which is located below sea floor  125 . The well system  100  includes a subsea conduit  130  that extends from a deck  112  of the platform  110  to a wellhead installation  140 , which may include one or more subsea blow-out preventers  145 . A wellbore  150  extends through the various earth strata including the formation  120 . Wellbore casing  160  is cemented within wellbore  150  by cement  165 . Platform  110  has a hoisting apparatus  114 , which may include a rotary table, and a derrick  116  for raising and lowering pipe strings, such as work string  170 . 
     The platform  110  also has a packing pump  118  for conducting gravel packing within production zones of the subterranean formation  120 . The packing pump  118  pumps a fluid slurry with a liquid carrier and particulate downhole for the packing and a clean-out bin (not shown) receives the portion of fluid slurry that returns to the surface. 
     The platform  110  includes a control system  119  that directs the operation of the well system  100 . The control system  119  can be used to control the packing pump  118  and downhole equipment, such as completion assembly  180  connected to the work string  170 . The control system  119  can include a computing device having a processor, memory, and display. The processor can be configured to perform at least some of the functions of a packing controller as disclosed herein. For example, the processor can automatically initiate a change in the gravel packing operation based on measurements or status. The display can be used to show a status determined by a packing controller. An operator can manually alter the gravel packing process based on the status. In addition to a visual presentation, computing device can also provide audible signals to indicate the status. For example, a first signal can be sounded for a screen-out warning, a second signal for screen-out, a third signal indicating a void, a fourth signal indicating no void, etc. The memory can be used to store measurements obtained by a packing detector and statuses determined by a packing controller. The control system  119  can be communicatively coupled to the completion assembly  180  or other downhole equipment via a communication system typically employed in a wellbore environment, including an acoustic system, fluid system, optical system, wired system, wireless system, or a combination of the various system. 
     Completion assembly  180  has been run within casing  160 . The completion assembly  180  can be used for gravel packing within production zones of interest, including a first zone  124  (e.g. a lower zone) and a second zone  128  (e.g. an upper zone) within the subterranean formation  120 . For gravel packing annular regions  162 ,  166 , the completion assembly  180  is lowered through the casing  160  to position screens  182 ,  184 , of the completion assembly  180  within the first zone  124  and the second zone  128 . Radiation tags and sensors can be used to position the screens  182 ,  184 , at the proper depth in the wellbore  150 . The radiation tags can be located inside casing  160  or adjacent thereto (e.g., inside the wellbore  150 ) at some known depth. Radiation tags  167  is shown in the wellbore  150  and radiation tag  169  is shown within the casing  160 . The sensors can be one or more sensors of packing monitors that are used to monitor the distribution of particulate along the length of the screens  182 ,  184 . Packing monitor  192  is used with screen  182  and packing monitor  194  is used with screen  184 . The packing monitors  192 ,  194 , determine a status of the particulate during gravel packing and can transmit the status to the control system  119  for modification of the gravel packing operation. The packing monitors  192 ,  194 , can be attached to the screens  182 ,  184 , as shown in  FIG. 1 . Alternatively, one or more packet monitors can be attached to an inner service tool string (not shown) that is positioned within the completion assembly  180 . The packing monitors  192 ,  194 , can be mechanically attached to a screen or tool string via a mechanical connection, such as via bolts, bands, integrated with the oilfield tubular, threaded, clamped, etc. Screen  182  and packing monitor  192  and screen  184  and packing monitor  194  can be part of can be part of a single gravel pack system. For example, screens  182 ,  184 , and packing monitors  192 ,  194 , can be part of a lower completion assembly, such as a dual zone selective gravel pack assembly that can gravel pack two tones in a single trip. Another type of gravel pack assembly, such as for packing a single zone, can also be used with the packing monitors  192 ,  194 . A gravel pack system can include additional components typically included with packer assemblies, such as packers that are used to control the lateral flow of particulate in the annulus. Packing monitor  230  of  FIGS. 2-3  provide an example of packing monitors  192 ,  194 . 
     When appropriately positioned, the completion assembly  180  may be run through various positions to assure proper operation thereof. Thereafter, a fluid slurry including a liquid carrier and a particulate, such as sand, gravel or proppants, is pumped down work string  170  to pack the annular regions  162  and  166  with the particulate. Various sleeves, or valves, of completion assembly  180  can be operated to direct the flow of the fluid slurry for packing. The sleeves can be operated by an inner service tool string. The sleeves can also he automatically operated by the packing monitor based on a packing status of the particulate in the annulus along a length of a sleeve. For example, packing monitor  192  may determine that screen-out is approaching for screen  182  and open and close sleeves of the completion assembly  180  to redirect the flow of the slurry out of zone  124 . The completion assembly  180  can be a tubing assembly that allows operating of sleeves without tool movement. For example, the tubing assembly of U.S. Pat. No. 10,711,572, which is incorporated herein by reference in its entirety, provides an example of an assembly that the packing monitor  192  can communicate with to operate sleeves. 
     When utilized, an inner service tool string located within the completion assembly  180  can be pulled out of the wellbore  150  after completion assembly  180  has been used to gravel pack the first and second zones  124 ,  128 . In the process of pulling an inner service tool string out of the wellbore  150 , an isolation plug of the completion assembly  180  may be set, a sliding sleeve in the first zone  124  may be closed, and a sliding sleeve in the second zone  128  may be closed. At this stage, the first and second zones  124 ,  128  can he fully isolated from each other, as well as the upper and lower portions of the wellbore  150 . With the first and second zones  124 ,  128  isolated, the inner service tool string can he fully pulled up hole, leaving the completion assembly  180  intact downhole. As this stage, an upper completion assembly (not shown) may he run downhole, and one or both of the sliding sleeves may he opened (e.g., mechanically or hydraulically opened), thus opening one or both of the first and second zones  124 ,  128  for production. Instead of utilizing an inner service tool string, completion assembly  180  can include sleeves that can he operated from the surface to isolate the first and second zones  124 ,  128  and open one or both for production. 
     Even though  FIG. 1  depicts a vertical well, it should be noted by one skilled in the art that the packing monitor and packing assembly as disclosed herein can also be used in other well configurations including, but not limited to, inclined wells, wells with restrictions, deviated wells or horizontal wells. For non-vertical wells, the packing controller of the packing monitor can be configured to compensate for the distribution of the particulate along a length of the screen according to an angle of the non-vertical wellbore, for example by noting the particulate concentration at different circumferential locations along a tubing string or by noting the particulate concentration at different axial positions along the length of the tubing string. Also, even though  FIG. 1  depicts an offshore operation, those skilled in the art understand that the principles of the disclosure are equally as applicable in other subterranean formations, including those encompassing both areas below exposed earth and areas below earth covered by fresh water. The packing monitor and gravel pack system disclosed herein can also be used with cased wellbores in addition to open-hole wellbores. 
       FIG. 2  illustrates a diagram of an example of a gravel packing system  200  constructed according to the principles of the disclosure. The gravel packing system  200  is shown with respect to a portion of a wellbore  250  having casing  252  that has been perforated in a production zone  254 . The gravel packing system  200  can also be used with an open-hole production zone, such as the first zone  124  or the second zone  128  of  FIG. 1 . The gravel packing system  200  includes a screen  210 , packers  220 , and a packing monitor  230 . A completion assembly  240  is also illustrated in wellbore  250 . The completion assembly  240  can be, for example, completion assembly  180  of  FIG. 1 . The screen  210  can be a part of the completion assembly  240 . 
     The screen  210  holds particulates  260  in place during production within an annulus  270  created between the screen  210  and the casing  252 . The packers  220  are positioned to contain the particulates in the annulus  270  within the production zone  254 . Various positions along the length of the screen  210  are denoted by the numbers one to nine. The numbers can correspond to feet or another selected distance, such as meters. Connected to the screen  210  is the packing monitor  230 . Various types of mechanical connections can be used to attach the packing monitor  230  to the screen  210 . 
     The packing monitor  230  is configured to observe packing of the particulates  260  in real-time within the annulus  270  during a packing process. The packing monitor  230  includes a packing detector  232  and a packing controller  236 . The packing detector  232  is configured to obtain stationary axial measurements indicating a presence of the particulates  260  within the annulus  270  at different positions along the length of the screen  210 . The packing detector  232  includes a group of sensors  234 , wherein each of the sensors  234  corresponds to a different position along the length of the screen  210 . The sensors  234  can be radiation sensors that obtain radiation measurements from the particulates  260  in the annulus  270 . One or more magnetic permeability sensors could also be used. The sensor corresponding to each position indicates the amount of particulate at that particular position of the screen  210  based on the radiation measurements. For example, numbers 1 to 9 are shown to indicate one foot to nine feet from the top to the bottom of screen  210 . Each of the sensors  234  from two feet to nine feet would obtain measurements indicating the presence of particulate  260 . The sensor  234  at the one foot position, wherein screen-out occurs, would not obtain radiation measurement from the particulate  260  in the illustrated example of  FIG. 2 . 
     The screen  210  and packing monitor  230  can be placed in the correct location within the production zone  254  by positioning one of the sensors  234  with respect to a radiation tag  256  located in the casing  250 . The completion string  240  can be lowered into the wellbore  250  to align one of the sensors  234  with the radiation tag  256 . The sensor  234  at the one foot position can be used for the alignment as shown in  FIG. 2 . The measurements obtained by the sensors  234  are sent to the packing controller  236  for analysis. 
     The packing controller  236  is configured to determine, based on the measurements, a status of the particulate  260  in the annulus  270  corresponding to the positions along the length of the screen  210 . The packing controller  236  can include a processor having the logic to process the measurements and provide a status. The status can indicate a level of the particulate  260  within the annulus  270  per position of the screen  210 . For example, the packing controller  236  can determine from the measurements that the particulate  260  is up to the two foot position of the screen  210 . Based on the two foot position level, the packing controller  236  can indicate that screen-out is approaching and provide a screen-out warning.  FIG. 4  illustrates an example of a plot representing the status of the particulate  260  in the annulus  270 . The status determined by the packing controller  236  can be transmitted to the surface wherein an action can be initiated to modify the packing process, such as adjust particulate concentration, slurry flow rates, or treatment pressure. The status, and/or the measurements, can be sent to a computing device, such as with the control system  119  for presentation or additional processing. Presentation of the status can be visual, audible, or a combination of both. 
     The packing controller  236  can include a communications interface configured to transmit the status to the surface. The communications interface can also transmit the measurements to the surface for processing. A wireless acoustic system employing repeaters, for example, can be used for communicating within the wellbore  250 . The communications interface can transmit one or more of the measurements or the status at different time intervals. The packing controller  236  can also include a memory configured to store the measurements, the status, or both at different time intervals. This stored data can transmitted up hole at a different time than when obtained or generated, i.e., not in real-time. In the example of  FIG. 3  wherein the packing monitor is connected to an inner working tool string, the stored data can be downloaded when the packing monitor  230  is returned to the surface. The packing controller  900  of  FIG. 9  provides an example of the configuration of the packing controller  236 . 
     The packing monitor  230  can also include one or more wellbore parameter sensor  238  that determines wellbore parameters in the zone  254 . The wellbore parameters, such as pressure and temperature, can be sent directly to the packing controller  236  and used as a secondary measurement(s) confirming when, for example, screen-out has occurred. The downhole measurements of the wellbore parameters can be beneficial for confirming a status downhole and automatically initiating a downhole action. 
       FIG. 3  illustrates a diagram of another example of a gravel packing system  300  constructed according to the principles of the disclosure. The gravel-packing system  300  includes screen  210 , packers  220 , packing monitor  230 , and an inner working tool string  310 . As with  FIG. 2 , the gravel packing system  300  is shown with respect to wellbore  250  having casing  252  that has been perforated in a production zone  254 . In the example of  FIG. 3 , however, the packing monitor  230  is attached to inner working tool string  310  instead of screen  210 . For the gravel packing system  300 , the status and/or measurements can still be transmitted up hole. Additionally, the data stored on the packing monitor  230  can be obtained when the inner working tool string  310  is tripped to the surface. The packing monitor  230  can still provide a status, such as the plot of  FIG. 4 , in gravel packing system  300  as in gravel packing system  200 . 
       FIG. 4  illustrates a plot  400  that shows an example of a status that can be generated by a packing monitor, such as packing monitor  230  in  FIGS. 2-3 . The plot  400  represents a status based on radiation measurements obtained by a packing detector, such as packing detector  232 . The status can be generated by a packing controller, such as packing controller  236 . The plot  400  includes an x axis corresponding to positions along the length of a screen, such as screen  210 , and a y axis indicating counts of radioactive measurements. The positions are in feet and correspond to the positions denoted on screen  210 . The plot  400  provides a status of the packing process and indicates that screen-out is approaching. A status can also indicate the quality of a gravel pack, such as indicate the presence of voids.  FIG. 5  illustrates an example of a void in a gravel pack. A particulate with different emission properties can be sequenced for different stages in the wellbore in order to provide a different measurement properties, such as radioactive or magnetic permeability properties, at different stages of the particulate placement. 
       FIG. 5  illustrates a diagram of an example of a portion of a wellbore  500  having two production zones  510 ,  520 , that are gravel packed using a gravel packing system  530  constructed according to the principles of the disclosure. The wellbore  500  includes casing  502  that has been perforated. The gravel packing system  530  includes a packer  532  that separates zones  510 ,  520 , a screen  534 , and packing monitors  536 ,  538 . The gravel packing system  530  can be part of a completion assembly. In this example, a single screen  534  is used for both production zones  510 ,  520 . Instead of a single sleeve, each production zone can have their own screen. An annulus  504  is defined by the casing  502  and the screen  534 . A radioactive tag  506  can be used to position the screen  534  is the proper position for production zones  510  and  520 . 
     The packing monitors  536 ,  538 , can be configured to operate as the packing monitor  230  of  FIGS. 2 and 3 . As such the packing monitors  536 ,  538 , are configured to determine a status of a particulate  540  within the annulus  504  at different positions along a length of the screen  534  within each respective production zone  510 ,  520 . The status is determined based on stationary axial measurements obtained during gravel packing of the productions zones  510 ,  520 . In this example the measurements are radiation measurements. The status for both production zones  510 ,  520 , can be sent up hole using, for example, wireless acoustics repeaters for at least a portion of the transmission. 
       FIGS. 6-7  illustrate examples of a status indicating the quality of gravel packing in the two different production zones  510 ,  520 .  FIGS. 6-7  illustrate plots having an x axis representing positions and y axis for radiation counts as in  FIG. 4 . The status for production zone  510  is represented by plot  600  of  FIG. 6 . Plot  600  indicates there are no voids in the annulus  504  in production zone  510 . The status for production zone  520  is represented by plot  700  of  FIG. 7 . Plot  700  indicates there is a void between the two feet to five feet positions of screen  534  in the annulus  504  in production zone  520 . The void is represented by the low amount of radiation counts detected between these positions. The counts measured in  FIGS. 6-7 , as with  FIG. 4 , can be, for example, alpha particles, beta particles, or gamma rays. 
       FIG. 8  illustrates a flow diagram of an example of a method  800  of gravel packing a portion of a wellbore carried out according to the principles of the disclosure. At least a portion of the method can be carried out by a packing monitor, such as packing monitor  230 , as disclosed herein. The method begins in step  805 . 
     In step  810 , a fluid slurry is pumped into an annulus of the wellbore. The annulus is partially defined by a screen and corresponds to a production zone of the wellbore. The fluid slurry includes a particulate and can be pumped in a conventional way performed in the industry. 
     Stationary axial measurements are obtained in step  820 . The stationary axial measurement indicate a presence of the particulate in the annulus at different positions along a length of the screen. The different positions can be evenly spaced apart at known distances. The positions can also be unevenly spaced apart. For example the positions on the lower part of screen can be separated by a distance of two feet and positions closer to the top of the screen can be separated by a distance of one foot. Accordingly, more measurements can be obtained closer to a position of screen-out to provide additional data for determining an action to take. The positions can be denoted by numbers, letters, or other known indicators that can be used to measure the depositing of a particulate along a screen during a gravel packing process. A packing detector such as disclosed herein can be used to obtain the stationary axial measurements. For example, an array of radiation sensors can be used to obtain the measurements. 
     In step  830 , a status of the particulate in the annulus at the different positions is determined based on the stationary axial measurements. The status can be determined by a packing controller as disclosed herein. The packing controller can be integrated with the packing detector in a single device. A portion of the packing controller can be located distal from the packing detector. For example, a processor of the packing controller can be located at the surface or in another location within the wellbore. The status can be represented by plots corresponding to the positions. The status can also be statements, such as a screen-out warning. The status can be determined in real time during the gravel packing. 
     The gravel packing is completed in a step  840  according to the status. For example, the status can indicate a void and completing the gravel packing can include a top-off of the particulate in the annulus. Advantageously, the top-off can be performed without tripping out, for example, an inner working tool string used for the gravel packing. 
     In another example, the status can provide a screen-out warning, and completing the gravel packing can include reducing pumping of the fluid slurry. As such, the gravel packing process can be modified to prevent overshooting screen-out. The status can also indicate screen-out has occurred, wherein completing of the gravel packing includes stopping the pumping of the fluid slurry and reversing out of the wellbore excess of the particulate. Responding to the statuses can be automatic, manual, or a combination of both. Sleeves can be automatically operated downhole via the packing controller to complete the gravel packing process, can be operated via the surface, or via a combination. The method  800  ends in a step  850 . The method  800  represents the gravel packing process for a single production zone. The method  800  can be repeated for another production zone in the wellbore or performed simultaneously in multiple production zones of the wellbore. For simultaneous operation, sleeves for each production zone can be independently operated based on a status for that production zone. 
       FIG. 9  illustrates a block diagram of an example of a packing controller  900  constructed according to the principles of the disclosure. The packing controller  900  or at least a portion thereof can be embodied as a series of operating instructions stored on a non-transitory computer-readable medium that direct the operation of a processor when initiated. At least a portion of the packing controller can be a computer program product that includes such operating instructions. The packing controller  900  provides an example of a packing controller that can be utilized with the packing monitors of  FIGS. 1, 2, 3, and 5 . 
     The packing controller  900  can be stored on a single computer or on multiple computers. The various components of the packing controller  900  can communicate via wireless or wired conventional connections. A portion of the packing controller  900  can be located downhole at one or more locations and other portions of the packing controller  900  can be located on a computing device or devices located at the surface. As described above, the packing controller  900  is part of a packing monitor and can be integrated in a single device with a packing detector. 
     The packing controller  900  can be configured to perform the various functions disclosed herein including receiving stationary axial measurements and based thereon determine a status of a particulate in an annulus of a wellbore at different positions along a length of a screen during a gravel packing process. The packing controller  900  includes a communications interface  910 , a memory  920 , and a processor  930 . 
     The communications interface  910  is configured to transmit and receive data. For example, the communications interface  910  receives measurements from a packet detector and transmits status determined based on the measurements. The communications interface  910  can also transmit action commands that initiate downhole actions, such as operating sleeves to control or modify a gravel packing. The action commands can be automatically communicated based on a determined status. The action commands can be automatically communicated via various types of connections, such as a wireless or wired connection, to a downhole sleeve to operate the sleeve without receiving an operating command from the surface. A communication protocol determined by the sleeve can be used. The communications interface  910  can also transmit wellbore parameters, such as pressure and temperature up hole. The wellbore parameters can be determined from a packing monitor during gravel packing. The wellbore parameters can provide back-up confirmation for a status. The communications interface  910  can communicate via communication systems used in the industry for wellbore. For example, wireless acoustic communication systems can be used. 
     The memory  920  is configured to store a series of operating instructions that direct the operation of the processor  930  when initiated, including the code representing the algorithms for determining statuses based on stationary axial measurements. The memory  920  is a non-transitory computer readable medium. Multiple types of memory can be used for data storage and the memory  920  can be distributed. 
     The processor  930  is configured to determine a status or statuses based on the received stationary axial measurements. For example, the processor  930  can determine that screen-out is approaching and also determine that there is a void. The processor  930  can also be configured to direct the operation of the packing controller  900 . As such, the processor  930  includes the necessary logic to communicate with the communications interface  910  and the memory  920  and perform the functions described herein to determine a status. Additionally the processor  930  can include the necessary logic to generate an action command to operate a downhole valve or sleeve. The action command can be communicated by the communications interface  910  using a required protocol. 
     A portion of the above-described apparatus, systems or methods may be embodied in or performed by various analog or digital data processors, wherein the processors are programmed or store executable programs of sequences of software instructions to perform one or more of the steps of the methods. A processor may be, for example, a programmable logic device such as a programmable array logic (PAL), a generic array logic (GAL), a field programmable gate arrays (FPGA), or another type of computer processing device (CPD). The software instructions of such programs may represent algorithms and be encoded in machine-executable form on non-transitory digital data storage media, e.g., magnetic or optical disks, random-access memory (RAM), magnetic hard disks, flash memories, and/or read-only memory (ROM), to enable various types of digital data processors or computers to perform one, multiple or all of the steps of one or more of the above-described methods, or functions, systems or apparatuses described herein. 
     Portions of disclosed examples or embodiments may relate to computer storage products with a non-transitory computer-readable medium that have program code thereon for performing various computer-implemented operations that embody a part of an apparatus, device or carry out the steps of a method set forth herein. Non-transitory used herein refers to all computer-readable media except for transitory, propagating signals. Examples of non-transitory computer-readable media include, but are not limited to: magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD-ROM disks; magneto-optical media such as floppy disks; and hardware devices that are specially configured to store and execute program code, such as ROM and RAM devices. Examples of program code include both machine code, such as produced by a compiler, and files containing higher level code that may be executed by the computer using an interpreter. 
     In interpreting the disclosure, all terms should be interpreted in the broadest possible manner consistent with the context. In particular, the terms “comprises” and “comprising” should be interpreted as referring to elements, components, or steps in a non-exclusive manner, indicating that the referenced elements, components, or steps may be present, or utilized, or combined with other elements, components, or steps that are not expressly referenced. 
     Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, because the scope of the present disclosure will be limited only by the claims. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present disclosure, a limited number of the exemplary methods and materials are described herein. 
     The summary section list various aspects that are disclosed herein. Each of these aspects can have one or more of the following additional elements in combination: Element  1 : wherein the packing detector includes multiple radiation sensors, and each one of the multiple sensors corresponds to a different one of the positions along the length of the screen. Element  2 : wherein the packing detector includes multiple magnetic permeability sensors, and each one of the multiple sensors corresponds to a different one of the positions along the length of the screen. Element  3 : wherein the packing monitor further includes a wellbore parameter sensor configured to determine parameters of the wellbore proximate the annulus. Element  4 : wherein the status indicates at least one of a void, a fill-level of the particulate, a screen-out warning, or screen-out. Element  5 : wherein the packing controller is further configured to automatically initiate a downhole action during a packing process based on the status. Element  6 : wherein the downhole action is operating a sleeve of a completion system in the wellbore. Element  7 : wherein the packing controller includes a memory configured to store one or more of the measurements and the status at different time intervals. Element  8 : wherein the packing controller further includes a communications interface configured to transmit the measurements, the status, or a combination thereof at different time intervals. Element  9 : wherein the packing controller is configured to determine the status in real-time during a gravel packing process. Element  10 : wherein the determining is performed in real time during the gravel packing. Element  11 : further comprising completing the gravel packing according to the status. Element  12 : wherein the status indicates a void and the completing includes a top-off of the particulate in the annulus. Element  13 : wherein the status provides a screen-out warning, and the completing includes reducing pumping of the fluid slurry. Element  14 : wherein the status indicates screen-out, and the completing includes stopping pumping of the fluid slurry and reversing out of the wellbore excess of the particulate. Element  15 : wherein the packing monitor is attached to the screen. Element  16 : wherein the packing monitor includes a packing detector having multiple radiation sensors configured to obtain the stationary axial measurements, and each one of the multiple sensors corresponds to one of the different positions. Element  17 : further comprising a packing controller configured to determine the status and automatically initiate a downhole action to modify the gravel packing based on the status. Element  18 : further comprising a packing controller configured to determine the status, wherein the packing controller includes a communications interface configured to transmit the status to the surface.