Patent Abstract:
A method and system for determining information about a wellbore with coiled tubing. A downhole device may be positioned within coiled tubing and run down the wellbore to determine diagnostic information about a location with the wellbore. The downhole device may store diagnostic information in a storage device that may be analyzed when the device is returned to the surface. A downhole device may be connected to the end of a string of coiled tubing that includes a diagnostic device and memory sealed in a chamber. A flow path past the chamber is in communication with the coiled tubing string permitting the flow of fluid past the chamber. A downhole device including a diagnostic device may be connected to a recess in an exterior of a coiled tubing string.

Full Description:
BACKGROUND 
     1. Field of the Disclosure 
     The embodiments described herein relate to a method and apparatus for a downhole device connected to coiled tubing to obtain diagnostic information of a wellbore. The downhole device may be connected to the interior of the coiled tubing. Alternatively, the downhole device may be connected to an exterior carrier portion of the coiled tubing. 
     2. Description of the Related Art 
     Natural resources such as gas and oil may be recovered from subterranean formations using well-known techniques. For example, a horizontal wellbore may be drilled within the subterranean formation. After formation of the horizontal wellbore, a string of pipe, e.g., casing, may be run or cemented into the well bore. Hydrocarbons may then be produced from the horizontal wellbore. 
     In an attempt to increase the production of hydrocarbons from the wellbore, the casing may be perforated and fracturing fluid may be pumped into the wellbore to fracture the subterranean formation. The fracturing fluid is pumped into the well bore at a rate and a pressure sufficient to form fractures that extend into the subterranean formation, providing additional pathways through which fluids being produced can flow into the well bores. The fracturing fluid typically includes particulate matter known as a proppant, e.g., graded sand, bauxite, or resin coated sand, that may be suspended in the fracturing fluid. The proppant becomes deposited into the fractures and thus holds the fractures open after the pressure exerted on the fracturing fluid has been released. 
     A production zone within a wellbore may have been previously fractured, but the prior fracturing may not have adequately fractured the formation leading to inadequate production from the production zone. Even if the formation was adequately fractured, the production zone may no longer be producing at adequate levels. Over an extended period of time, the production from a previously fractured horizontal wellbore may decrease below a minimum threshold level. One technique in attempting to increase the hydrocarbon production from the wellbore may be the re-fracturing of some of the previously fractured locations of the horizontal wellbore. However, it may not be beneficial to re-fracture every previously fractured location. It may be beneficial to use a diagnostic tool to analyze the production zones in a horizontal wellbore to determine which zones should be re-fractured. 
       FIG. 8  shows a prior art diagnostic tool  22  conveyed into a wellbore  10  on coiled tubing  40  via a wellhead  16 . The coiled tubing  40  moves the diagnostic tool  22  down the wellbore  10  along the casing  18  until the diagnostic tool  22  is positioned at a desired location. The diagnostic tool  22  is connected to the surface via a cable  14 , which transmits diagnostic information obtained from the device  22 . The cable  14  and diagnostic tool  22  are connected to the end of the coiled tubing  40  via a cable head  20  and connector  21 . Prior to running the diagnostic tool  22  into the wellbore  10 , coiled tubing  40  may be run into the wellbore  10  to conduct a clean-out procedure. The coiled tubing  40  is then tripped out of the wellhead  16  and the diagnostic tool  22  and cable  14  may be connected to the coiled tubing  40  for a second trip into the wellbore  10  with the coiled tubing  40 . The positioning of the cable  14  outside of the coiled tubing  40  as well as the diagnostic tool  22  being connected to end of the coiled tubing  40  may present an increased chance the coiled tubing  40  becomes stuck within the wellbore  10 . It may also be beneficial to permit a cleanout procedure and conveyance of a diagnostic tool  22  into a wellbore in a single trip of coiled tubing  40 . 
     SUMMARY 
     The present disclosure is directed to a downhole device connected to coiled tubing that substantially overcomes some of the problems and disadvantages discussed above. 
     One embodiment is a method of determining information about the production from a zone of a wellbore comprising running a downhole device into a wellbore. The device comprises an electronic device positioned inside of a housing within an interior of coiled tubing. The method includes positioning the downhole device adjacent a first zone of the wellbore, determining diagnostic information of the first zone of the wellbore, and storing the determined diagnostic information of the first zone in a memory device. 
     The method may include connecting the housing to the interior of coiled tubing. The method may include pumping fluid down the interior of the coiled tubing past the downhole device while determining diagnostic information of the first zone. The method may include positioning the downhole device adjacent a second zone of the wellbore, determining diagnostic information of the second zone of the wellbore, and storing the determined diagnostic information of the second zone in the memory device. The electronic device may be a logging tool. The method may include pulling the downhole device out of the wellbore and analyzing the diagnostic information of the first zone stored in the memory device. 
     One embodiment is a method of determining information about the production from a zone of a wellbore comprising running a downhole device into a wellbore. The downhole device comprises an electronic device positioned inside of a housing connected to a recess in an exterior of coiled tubing. The method includes positioning the downhole device adjacent a first zone of the wellbore, determining diagnostic information concerning the first zone of the wellbore, and storing the determined diagnostic information of the first zone in a memory device. 
     The electronic device may be a logging tool. The method may further comprise positioning the downhole device adjacent a second zone of the wellbore, determining diagnostic information of the second zone of the wellbore, and storing the determined diagnostic information of the second zone in the memory device. The method may include pulling the downhole device out of the wellbore and analyzing the diagnostic information of the first zone stored in the memory device. 
     One embodiment is a system to monitor a zone of a wellbore. The system comprises a string of coiled tubing and a housing having a first end and a second end. The housing is closed at the first end and is closed at the second end and at least one of the ends being selectively closed to permit access into the housing. The system includes an electronic device positioned within the housing. The electronic device is configured to obtain diagnostic information of a wellbore. The housing is connected to a portion of an interior of the string of coiled tubing with a flow path between the housing and the interior of the string of coiled tubing. 
     The electronic device may be a logging tool. The system may include a memory storage device connected to the electronic device. The housing may be welded to the interior of the string of coiled tubing. The housing may be positioned between an end of the string of coiled tubing and a location ten feet from the end of the string of coiled tubing, the location being along the string of coiled tubing. 
     One embodiment is a system to monitor a zone of a wellbore. The system comprises a string of coiled tubing and a housing having a first end and a second end. The housing is closed at the first end and is closed at the second end and at least one of the ends being selectively closed to permit access into the housing. The system includes an electronic device positioned within the housing. The electronic device is configured to obtain diagnostic information of a wellbore. The housing is connected to a recess in a portion of an exterior of the string of coiled tubing with a flow path in an interior of the string of coiled tubing past the recess. 
     The electronic device may be a logging tool. The system may include a memory storage device connected to the electronic device. The housing may be welded to the exterior of the string of coiled tubing. The housing may be positioned between an end of the string of coiled tubing and a location ten feet from the end of the string of coiled tubing, the location being along the string of coiled tubing. 
     One embodiment is a system to monitor a wellbore. The system comprises a string of coiled tubing and a housing having a first end, a second end, at least one inner wall forming a cavity, and a flow path from the first end to the second end. The cavity is selectively sealed from the flow path. The housing is connected to an end of the string of coiled tubing. The system includes an electronic device positioned within the selectively sealed cavity of the housing. The electronic device is configured to obtain diagnostic information of a wellbore. The system includes a memory storage device connected to the electronic device. The memory storage device is positioned within the selectively sealed cavity of the housing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an embodiment of a downhole device positioned within a housing inside of coiled tubing; 
         FIG. 2  shows an end cross-section view of an embodiment of a downhole device positioned within a housing inside of coiled tubing; 
         FIG. 3  shows an end cross-section view of an embodiment of a downhole device positioned within a housing inside of coiled tubing within casing; 
         FIG. 4  shows an embodiment of a downhole device positioned adjacent a first zone of a wellbore; 
         FIG. 5  shows an embodiment of a downhole device positioned adjacent a second zone of a wellbore; 
         FIG. 6  shows an embodiment of a downhole device positioned within a housing connected to the outside of coiled tubing; 
         FIG. 7  shows an embodiment of a downhole device that may be connected to the end of coiled tubing; and 
         FIG. 8  shows a prior art downhole device connected to coiled tubing. 
     
    
    
     While the disclosure is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the disclosure is not intended to be limited to the particular forms disclosed. Rather, the intention is to cover all modifications, equivalents and alternatives falling within the scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
       FIG. 1  shows an embodiment of a downhole device  100  that may be connected to the interior of coiled tubing  40 . The downhole device  100  may include a housing  50  that is connected to the inside of the coiled tubing  40 . The housing  50  may be connected to the inside of the coiled tubing  40  by various mechanisms such as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure. For example, the housing  50  could be welded to the interior of the coiled tubing  40 . An electronic device  60  configured to monitor various aspects of a production zone (e.g.  30   a  or  30   b  shown in  FIG. 4  and  FIG. 5 ) of a wellbore  10  is positioned within the housing  50 . The coiled tubing  40  is used to run the device  100  down a wellbore  10  within casing or tubing  18  and position the electronic device  60  of the downhole device  100  at a desired location within the wellbore  10 . The ends of the housing  50  are closed so that fluid flows around the housing through a flow area  45  (shown in  FIG. 2 ) between the housing  50  and the coiled tubing  40  as shown by arrows  41  in  FIG. 1 . The positioning of the downhole device  100  inside of the coiled tubing  40  may permit the attachment of a bottom hole assembly to the bottom of the coiled tubing  40  that is adapted for other purposes. A conventional logging tool connected to the bottom of the coiled tubing  40  may prevent the connection of an additional bottom hole assembly to the coiled tubing  40 . 
     The downhole device  100  is preferably connected to the interior of the coiled tubing  40  near the downhole end of the coiled tubing. For example, the downhole device  100  may be positioned flush with the end of the coil or between the end of the coiled and ten (10) feet from the end of the coiled tubing  40 .  FIG. 1  shows a distance, D, from the end of the coiled tubing  40  within which the downhole device  100  is preferably positioned within. The distance, D, may be various lengths. For example, D may be two (2) feet, which is approximately shown in  FIG. 1 . However, this distance is for illustrative purposes only and may be varied as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure. Preferably, the distance D may be approximately ten (10) feet. Coiled tubing  40  is often inserted into a wellbore  10  to perform a cleaning operation prior to other wellbore operations. The insertion of the downhole device  100  inside of the coiled tubing  40  permits the transmittal of an electronic device  60 , which may be a diagnostic tool, into the wellbore  10  during the cleaning trip into the wellbore  10 . The housing  100  connected inside of the coiled tubing  40  may provide added protection as the electronic device  60 , which may be fragile, is tripped in and out of the wellbore  10 . The addition of the housing  50  to the end of the coiled tubing string  40  may provide higher rigidity at the end of the coiled tubing string  40 , which may aid in the insertion of the coiled tubing string  40  into a wellbore  10 , in particular if the wellbore  10  is a horizontal wellbore. 
       FIG. 2  shows an end cross-section view of the downhole device  100  connected to an interior portion of the coiled tubing  40  creating a flow path  45  between the housing  50  of the device  100  and the rest of the interior of the coiled tubing  40  that is not connected to the housing  50 . The outer diameter of the housing  50  may be configured to permit an adequate flow path past the housing  50 . The housing  50  encloses an electronic device  60  that may be used to analyze the condition of the wellbore  10  and its surroundings. For example, the electronic device  60  may be a logging tool also referred to as a diagnostic tool. The diagnostic information gathered from the electronic device  60  may be stored on a memory device  70  also positioned within the housing  50 . The diagnostic information stored on the memory device  70  may then be analyzed after the device  100  is removed from the wellbore  10 .  FIG. 3  shows an end cross-section view of a downhole device  100  connected to coiled tubing  40  positioned within casing, or tubing,  18  of a wellbore. The device creates a flow area  45  between the housing  50  of the device  100  and the coiled tubing  40 . Likewise, the coiled tubing  40  creates a flow area  25  between the exterior of the coiled tubing  40  and the casing  18 . The flow area  45  between the housing  50  and the coiled tubing  40  may permit the pumping of fluid down the coiled tubing  40  during the capturing of diagnostic information from the electronic device  60 . The housing  50  may also act as a fluid displacer, which may enhance the response on neutralizing wellbore fluids. 
       FIG. 4  shows the downhole device  100  connected to coiled tubing  40  being positioned adjacent a first zone  30   a  of a wellbore  10 . The electronic device  60  of the downhole device may be used to determine whether the first zone  30   a  should be re-fractured during a re-fracturing procedure. For example, the downhole device  100  may be run into the wellbore  10  to determine which locations of the wellbore should be re-fractured by the process disclosed in related and commonly owned U.S. patent application Ser. No. 14/091,677 filed on Nov. 27, 2013 entitled System and Method for Re-fracturing Multizone Horizontal Wellbore, which is incorporated by reference herein in its entirety. 
     The electronic device  60  of the downhole device may be adapted to obtain various information about a desired location of a wellbore  10 . The diagnostic device  60  of the downhole device  100  may provide information concerning the temperature, pressure, fluid flow, and formation. The electronic device  60  may use various mechanisms to obtain diagnostic information as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure. For instance, the device  60  may generate pulsed neutrons that penetrate the housing  50  and reflect off the wellbore fluid as well as the wellbore  10  and surrounding formation measuring its activity. All of the diagnostic information gathered by the electronic device  60  may be stored in the memory device  70  for later analysis. 
     The coiled tubing  40  may be used to position the downhole device  100  adjacent a first zone  30   a  of a wellbore  10  so that the electronic device  60  may obtain diagnostic information concerning the first zone  30   a . This diagnostic information is stored in the memory device  70  and may be used later to determine whether it would be beneficial to re-fracture the first zone  30   a  during a re-fracturing process. After storing the diagnostic information for the first zone  30   a , the coiled tubing  40  may be used to position the downhole device  100  adjacent a second zone  30   b  of the wellbore  10  as shown in  FIG. 5 . The electronic device  60  may then obtain diagnostic information concerning the second zone  30   b , which may be stored in the memory device  70 . This process may be repeated until all desired locations within the wellbore  10  have been analyzed by the electronic device  60 . 
       FIG. 6  shows an end cross-section view of an embodiment of a downhole device  100  connected to the exterior of coiled tubing  140 . The coiled tubing  140  includes a carrier portion  141 , which is a concave portion that creates a recess for the placement of downhole device  100 . The housing  50  of the downhole device  100  may be connected to the recess in the coiled tubing  140  by various means. For example, the housing  50  may be welded to the carrier portion  141  of the coiled tubing  140 . The carrier portion  141  may be connected to coiled tubing  140  at connection points  142 . For example, the carrier portion  141  may be welded to the coiled tubing at connection points  142 . The carrier portion  141  may be formed from crimping the coiled tubing  140  to form bends at connection points  142  forming a recess for the positioning of the downhole device  100 . The coiled tubing  140  includes a flow path  145  between the interior of the coiled tubing  140  and the carrier portion  141 . The downhole device  100  includes an electronic device  60  used to diagnose conditions of the wellbore  10  and memory device  70  protected by housing  50 . The coiled tubing  140  may be used to positioned the downhole device  100  at desired locations within the wellbore  10  to obtain diagnostic information as detailed herein. As shown in  FIG. 6 , the addition of the downhole device  100  to the coiled tubing  140  may result in substantially the same outer diameter of the coiled tubing  140  if it did not contain the carrier portion  141 . 
       FIG. 7  shows an exploded view of an embodiment of a downhole device  200  that may be connected to the end of a coiled tubing string  240  by a connector  270 . The downhole device  200  includes an electronic device  60  that is configured as a wellbore diagnostic tool and a memory device  70  positioned within a cavity  205  within the downhole device  200 . As disclosed herein, the electronic device  60  may be positioned at various locations within the wellbore to obtain information concerning the wellbore  10  that may be stored in the memory device  70  for later analysis. The downhole device  200  may be formed by machining a housing  201  that includes an flow path  245  that is in communication with the interior of the coiled tubing  240  and a cavity that is formed by inner wall  202  and end caps  210  and  215 . End caps  210  and  215  seal the cavity  205  from fluids flowing through the flow path  245  of the downhole device. One or both of the end caps  210  and  215  may be selectively disconnected form the cavity  205  to permit access to the cavity  205  as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure. The end caps  210  and  215  may be connected to the cavity  205  by various mechanisms as would be appreciated by one of ordinary skill in the art having the benefit of this disclosure. Various mechanisms may be used to selectively seal the chamber  205  from the flow path  245  within the device  200 . For example, one end may be permanently closed with the other including a removable plugging element. 
     Although this invention has been described in terms of certain preferred embodiments, other embodiments that are apparent to those of ordinary skill in the art, including embodiments that do not provide all of the features and advantages set forth herein, are also within the scope of this invention. Accordingly, the scope of the present invention is defined only by reference to the appended claims and equivalents thereof.

Technology Classification (CPC): 4