A method for performing operations and for improving production in a well includes the steps of: providing radio identification devices at known locations in the well, and providing a reader device configured to read the identification devices, and to control the operations responsive to signals from the identification devices. The method also includes the steps of providing a process tool, and transporting the process tool and the reader device through the well. The reader device is programmed to control the process tool upon reception of a response signal from a selected identification device. The method can be used to perform perforating processes, packer setting processes, bridge plug setting processes, logging processes, inspection processes, chemical treating processes, and cleaning processes. In addition, the method can be performed dynamically by controlling the tool as it moves through the well, or statically by stopping the tool at a particular location within the well. A system for performing the method includes the identification devices, the reader device, the process tool, and a computer or controller. In addition the identification devices can be placed in casing collars of the well and can be configured as passive devices or as active devices.

CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/173,693 which is a continuation of U.S. patent application Ser. No. 10/323,536 filed on Dec. 18, 2002, now U.S. Pat. No. 7,400,263, which is a continuation of U.S. patent application Ser. No. 09/586,648, filed on Jun. 1, 2000, now U.S. Pat. No. 7,283,061 which is a continuation-in-part of patent application Ser. No. 09/286,650 filed Apr. 6, 1999, now U.S. Pat. No. 6,333,699, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/098,284, filed on Aug. 28, 1998, now abandoned. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to generally to wells used in the production of fluids such as oil and gas. More specifically, this invention relates to a method and system for performing various operations and for improving production in wells. 
     BACKGROUND OF THE INVENTION 
     Different operations are performed during the drilling and completion of a subterranean well, and also during the production of fluids from subterranean formations via the completed well. For example, different downhole operations are typically performed at some depth within the well, but are controlled at the surface. 
     A perforating process is one type of downhole operation that is used to perforate a well casing. A conventional perforating process is performed by placing a perforating tool (i.e., perforating gun) in a well casing, along a section of the casing proximate to a geological formation of interest. The perforating tool carries shaped charges that are detonated using a signal transmitted from the surface to the charges. Detonation of the charges creates openings in the casing and concrete around the casing, which are then used to establish fluid communication between the geological formation, and the inside diameter of the casing. 
     Another example of a downhole operation is the setting of packers within the well casing to isolate a particular section of the well or a particular geological formation. In this case, a packer can be placed within the well casing at a desired depth, and then set by a setting tool actuated from the surface. Other exemplary downhole operations include the placement of logging tools at a particular geological formation or depth within the well casing, and the placement of bridge plugs, casing patches, tubulars, and associated tools in the well casing. 
     One critical aspect of any downhole operation involves ascertaining the depth in the well where the operation is to be performed. The depth is typically ascertained using well logs. A conventional well log includes continuous readings from a logging instrument, and an axis which represents the well depths at which the readings were obtained. The instrument readings measure rock characteristics such as natural gamma ray radiation, electrical resistivity, density and acoustic properties. Using these rock characteristics geological formations of interest within the well, such as oil and gas bearing formations, can be identified. The well is initially logged “open hole” which becomes the bench mark for all future logs. After the well is cased, a cased hole log is then prepared and correlated, or “tied in”, to the open hole log. 
     Using the logs and a positioning mechanism, such as a wire line or coiled tubing, coupled to an odometer, a tool can be placed at a desired depth within the well, and then actuated as required to perform the downhole operation. One problem with conventional logging and positioning techniques is that it is difficult to accurately identify the depth of the tool, and to correlate the depth to the open hole logs. 
       FIG. 1  illustrates a prior art perforating process being performed in an oil and gas well  10 . The well  10  includes a well bore  12 , and a casing  14  within the well bore  12  surrounded by concrete  16 . The well  10  extends from an earthen surface  18  through geological formations within the earth, which are represented as Zones A, B and C. The casing  14  is formed by tubular elements, such as pipe or tubing sections, connected to one another by collars  20 . In this example the tubular elements that form the casing  14  are about 40 feet long so that the casing collars  20  are forty feet apart. However, tubular elements with shorter lengths (e.g., twenty feet) can be interspersed with the forty feet lengths to aid in depth determinations. Thus in  FIG. 1  two of the casing collars  20  are only twenty feet apart. 
     For performing the perforating operation a perforating tool  22  has been lowered into the casing  14  on a wire line  24 . A mast  26  and pulleys  28  support the wire line  24 , and a wire line unit  30  controls the wire line  24 . The wire line unit  30  includes a drive mechanism  32  that lowers the wire line  24  and the tool  22  into the well  10 , and raises the wire line  24  and the tool  22  out of the well  10  at the completion of the process. The wire line unit  30  also includes an odometer  34  that measures the unwound length of the wire line  24  as it is lowered into the well  10 , and equates this measurement to the depth of the tool  22  within the well. 
     During formation of the well  10  an open hole log  36  was prepared. The open hole log  36  includes various instrument readings, such as gamma ray readings  38  and spontaneous potential (SP) readings  40  which are plotted as a function of depth in feet. For simplicity only a portion of the open hole log  36 , from about 7000 feet to about 7220 feet, is illustrated. However, in actual practice the entire well  10  from the surface  18  to the bottom of the well  10  may be logged. The open hole log  36  permits skilled artisans to ascertain the oil and gas containing formations within the well  10  and the most productive intervals of those formations. For example, based on the gamma ray readings  38  and the SP readings  40  it is determined that Zone A may contain oil and gas reserves. It is thus desired to perforate the casing  14  along a section thereof proximate to Zone A. 
     In addition to the open hole log  36 , following casing of the well  10 , cased hole gamma ray readings  44  are made, and a casing collar log  42  can be prepared. The casing collar log  42  is also referred to as a PDC log (perforating depth control log). The casing collar log  42  can be used to identify the section of the casing  14  proximate to Zone A where the perforations are to be made. 
     Using techniques and equipment that are known in the art, the casing collar log  42  can be accurately correlated, or “tied in”, to the open hole log  36 . However, using conventional positioning mechanisms, such as the wire line unit  30 , it may be difficult to accurately place the perforating tool  22  at the required depth within the well. For example, factors such as stretching, elongation from thermal effects, sinusoidal and helical buckling, and deformation of the wire line  24  can affect the odometer readings, and the accuracy of the odometer readings relative to the open hole odometer readings. 
     Thus, as shown in  FIG. 1 , the odometer readings which indicate the depth of the perforating tool  22 , may not equate to the actual depths, as reflected in the open hole log  36  and the casing collar log  42 . In this example, the odometer readings differ from the depths identified in the open hole log  36  and the casing collar log  42  by about 40 feet. With this situation, when the perforating tool  22  is fired, the section of casing  20  proximate to Zone A may be only partially perforated, or not perforated at all. 
     Because of these tool positioning inaccuracies, various correlative joint logging and wire logging techniques have been developed in the art. For example, one prior art technique uses electronic joint sensors, and electrically conductive wire line, to determine joint-to-joint lengths, and to correlate the odometer readings of the wire line to the casing collar log. Although these correlative joint logging and wire line logging techniques are accurate, they are expensive and time consuming. In particular, additional crews and surface equipment are required, and additional wire line footage charges are incurred. 
     In addition to tool positioning inaccuracies, computational errors also introduce inaccuracies in depth computations. For example, a tool operator can make computational errors by thinking one number (e.g., 7100), while the true number may be different (e.g., 7010). Also, the tool operator may position the tool by compensating a desired amount in the uphole direction, when in reality the downhole direction should have been used. These computational errors are compounded by fatigue, the weather, and communication problems at the well site. 
     It would be desirable to obtain accurate depth readings for downhole tools without the necessity for complicated and expensive correlative joint logging and wire logging techniques. In addition, it would be desirable to control down hole operations and processes without having to rely on inaccurate depth readings contaminated by computational errors. The present invention is directed to an improved method and system for performing operations and processes in wells, in which the depths of down hole tools are accurately ascertained and used to control the operations and processes. 
     Another limitation of conventional downhole operations that are dependent on depth measurements, is that downhole tools must first be positioned in the well, and then actuated from the surface. This requires additional time and effort from well crews. In addition, surface actuation introduces additional equipment and variables to the operations. It would be advantageous to be able to control downhole operations without the requirement of surface actuation of the downhole tools. With the present invention actuation of downhole tools can be performed in the well at the required depth. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention a method and a system for performing various operations in wells, and for improving production in wells, are provided. Exemplary operations that can be performed using the method include perforating processes, packer setting processes, bridge plug setting processes, logging processes, inspection processes, chemical treating processes, casing patch processes, jet cutting processes and cleaning processes. Each of these processes, when performed in a well according to the method, improves the well and improves production from the well. 
     In an illustrative embodiment the method is used to perform a perforating process in an oil or gas production well. The well includes a well bore, and a well casing, extending from an earthen or subsea surface into various geological zones within the earth. The well casing includes lengths of pipe or tubing joined together by casing collars. 
     The method includes the initial step of providing identification devices at spaced intervals along the length of the well casing. The identification devices can comprise active or passive radio identification devices installed in each casing collar of the well casing. Each radio identification device is uniquely identified, and its depth, or location, within the well is accurately ascertained by correlation to well logs. Similarly, each casing collar is uniquely identified by the radio identification device contained therein, and a record of the well including the depth of each casing collar and identification device is established. 
     The method also includes the step of providing a reader device, and a transport mechanism for moving the reader device through the well casing proximate to the identification devices. In the illustrative embodiment the reader device comprises a radio frequency transmitter and receiver configured to provide transmission signals for reception by the identification devices. The identification devices are configured to receive the transmission signals, and to transmit response signals back to the reader device. The transport mechanism for the reader device can comprise a wire line, tubulars, coil tubing, a robotic mechanism, a fluid transport mechanism such as a pump or a blower, a free fall arrangement, or a controlled fall arrangement such as a parachute. 
     In addition to transmitting and receiving signals from the identification devices, the reader device is also configured to transmit control signals for controlling a process tool, as a function of the response signals from the identification devices. For example, the reader device can control a perforating tool configured to perforate the well casing. Specifically, the reader device and the perforating tool can be transported together through the well casing past the identification devices. In addition, the reader device can be programmed to transmit the control signal to detonate the perforating tool, upon reception of a response signal from an identification device located at a predetermined depth or location within the well. Stated differently, the reader device can be programmed to control the perforating tool responsive to locating a specific identification device. 
     As other examples, the reader device can be configured to control setting tools for packers, bridge plugs or casing patches, to control instrument readings from logging tools, and to control jet cutters and similar tools. With the method of the invention the true depth of the process tool can be ascertained in real time by the reader device using response signals from the identification devices. Accordingly, there is no need to ascertain the depth of the tool using an odometer, and expensive wire logging techniques. In addition, operator computational errors are reduced because true depth readings can be provided without the requirement of additional computations. Further, for some processes, there is no need to transmit signals to the surface, as the reader device can be programmed to control the process in situ within the well. 
     However, it is to be understood that the method of the invention can also be practiced by transmission of the control signals from the reader device to a controller or computer at the surface, and control of the process tool by the controller or computer. In addition, control of the process tool can be performed dynamically as the process tool moves through the well with the reader device, or statically by stopping the process tool at a required depth. Further, the method of the invention can be used to control a multi stage process, or to control a tool configured to perform multiple processes. For example, a combination packer setting and perforating tool can be configured to perform packer setting and perforating processes, as a function of true depth readings obtained using the method of the invention. 
     In the illustrative embodiment the system includes the identification devices installed in casing collars at spaced intervals along the well casing. The identification devices include a programmable element, such as a transceiver chip for receiving and storing identification information, such as casing collar and depth designations. Each identification device can be configured as a passive device, an active device having an antenna, or a passive device which can be placed in an active state by transmission of signals through well fluids. 
     The system also includes the reader device and the process tool configured for transport through the well casing. In addition to the transmitter and receiver, the reader device includes one or more programmable memory devices, such as semiconductor chips configured to receive and store information. The reader device also includes a power source such as a power line to the surface, or a battery. In addition, the reader device includes a telemetry circuit for transmitting the control signals, which can be used to control the process tool, and to provide depth and other information to operators and equipment at the surface. The system can also include a computer configured to receive and process the control signals, and to provide and store information in visual or other form for well operators and equipment. Further, the system can include a controller configured to process the control signals for controlling the process tool and various process equipment. The controller can be located at the surface, or on the process tool, to provide a self contained system. Also, the system can be transported to a well site in the form of a kit, and then assembled at the well site. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of a prior art downhole operation being performed using well logs and odometer readings from a tool positioning mechanism; 
         FIG. 2  is a flow diagram illustrating steps in the method of the invention for controlling a perforating process in a well; 
         FIGS. 3A and 3B  are schematic cross sectional views illustrating a system constructed in accordance with the invention for performing the perforating process; 
         FIG. 3C  is an enlarged portion of  FIG. 3B , taken along section line  3 C, illustrating a perforating tool of the system; 
         FIG. 3D  is an enlarged portion of  FIG. 3A , taken along section line  3 D, illustrating a reader device and an identification device of the system; 
         FIG. 3E  is an enlarged cross sectional view taken along section line  3 E of  FIG. 3D  illustrating a portion of the reader device; 
         FIG. 3F  is a side elevation view of an alternate embodiment active reader device and threaded mounting device; 
         FIG. 4A  is an electrical schematic for the system; 
         FIG. 4B  is a view of a computer screen for a computer of the system; 
         FIGS. 5A and 5B  are schematic views illustrating exemplary spacer elements for spacing the reader device of the system from the perforating tool of the system; 
         FIGS. 6A-6D  are schematic cross sectional views illustrating various alternate embodiment transport mechanisms for the system; 
         FIGS. 7A and 7B  are schematic cross sectional views illustrating an alternate embodiment system constructed in accordance with the invention for performing a packer setting process in a well; 
         FIG. 7C  is an enlarged portion of  FIG. 7A  taken along section line  7 C illustrating a threaded connection of a tubing string of the alternate embodiment system; and 
         FIG. 8A-8C  are schematic cross sectional views illustrating an alternate embodiment multi stage method and system of the invention for performing a packer setting and a perforating processes in combination. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to  FIG. 2 , broad steps in a method for controlling an operation or process in a subterranean well in accordance with the invention are illustrated. The method, broadly stated, includes the steps of: 
     A. Providing a process tool. 
     B. Providing a reader device in signal communication with the process tool. 
     C. Providing a transport mechanism for the process tool and the reader device. 
     D. Providing spaced identification devices in a well casing readable by the reader device. 
     E. Uniquely identifying each identification device and determining its depth, or location, in the well using well logs. 
     F. Programming the reader device to transmit a control signal to the process tool upon reception of a response signal from a selected identification device. 
     G. Transporting the process tool and the reader device through the well casing. 
     H. Reading the identification devices using the reader device. 
     I. Transmitting the control signal to the process tool upon reception of the signal from the selected identification device to actuate the process tool at a selected depth. 
     Referring to  FIGS. 3A-3D , a system  50  constructed in accordance with the invention is illustrated. The system  50  is installed in a subterranean well  52 , such as an oil and gas production well. In this embodiment the system  50  is configured to perform a perforating process in the well  52 . The perforating process performed in accordance with the invention provides an improved well  52 , and improves production from the well  52 . 
     The well  52  includes a well bore  54 , and a well casing  56  within the well bore  54  surrounded by concrete  56 . The well  52  extends from an earthen surface  60  through geological formations within the earth, which are represented as Zones E, F and G. The earthen surface  60  can be the ground, or alternately a structure, such as an oil platform located above water. In the illustrative embodiment, the well  52  extends generally vertically from the surface  60  through Zones E, F, and G. However, it is to be understood that the method can also be practiced on inclined wells, and on horizontal wells. 
     The well casing  56  comprises a plurality of tubular elements  62 , such as lengths of metal pipe or tubing, connected to one another by collars  64 . The casing  56  includes an inside diameter adapted to transmit fluids into, or out of, the well  52 , and an outside diameter surrounded by the concrete  58 . The collars  64  can comprise couplings having female threads adapted for mating engagement with male threads on the tubular elements  62 . Alternately, the collars  64  can comprise weldable couplings adapted for welding to the tubular elements  62 . 
     Also in the illustrative embodiment the casing  56  is illustrated as having the same outside diameter and inside diameter throughout its length. However, it is to be understood that the casing  56  can vary in size at different depths in the well  52 , as would occur by assembling tubulars with different diameters. For example, the casing  56  can comprise a telescoping structure in which the size thereof decreases with increasing depth. 
     Based on an open hole well log ( 36 - FIG. 1 ), or other information, it is determined that Zone F of the well  52  may contain oil and gas. It is thus desired to perforate the casing  56  proximate to Zone F to establish fluid communication between Zone F, and the inside diameter of the well casing  56 . 
     For performing the perforating process, the system  50  includes a perforating tool  68 , and a reader device  70  in signal communication with the perforating tool  68 . The system  50  also includes a plurality of identification devices  72  ( FIG. 3D ) attached to the collars  64  on the casing  56 , and readable by the reader device  70 . In addition, the system  50  includes a transport mechanism  66 W for transporting the perforating tool  68  and the reader device  70  through the well casing  56  to Zone F. If desired, the system  50  can be transported to the well  52  as a kit, and then assembled at the well  52 . 
     As shown in  FIG. 3C , the perforating tool  68  includes a detonator  74  (illustrated schematically) and a detonator cord  76  in signal communication with the detonator  74 . The detonator  74  can comprise a commercially available impact or electrical detonator configured for actuation by a signal from the reader device  70 . Similarly, the detonator cord  76  can comprise a commercially available component. The detonator  74  and the detonator cord  76  are configured to generate and apply a threshold detonating energy to initiate a detonation sequence of the perforating tool  68 . In the illustrative embodiment, the detonator  74  is located on, or within, the perforating tool  68 . 
     As shown in  FIG. 3C , the perforating tool  68  also includes one or more charge carriers  78  each of which comprises a plurality of charge assemblies  80 . The charge carriers  78  and charge assemblies  80  can be similar to, or constructed from, commercially available perforating guns. Upon detonation, each charge assembly  80  is adapted to blast an opening  82  through the casing  56  and the concrete  58 , and into the rock or other material that forms Zone F. 
     As shown in  FIG. 3D , each collar  64  includes an identification device  72 . Each identification device  72  can be attached to a resilient o-ring  86  placed in a groove  84  within each collar  64 . 
     In the illustrative embodiment, the identification devices  72  comprise passive radio identification devices (PRIDs). PRIDs are commercially available and are widely used in applications such as to identify merchandise in retail stores, and books in libraries. The PRIDs include a circuit which is configured to resonate upon reception of radio frequency energy from a radio transmission of appropriate frequency and strength. Passive PRIDs do not require a power source, as the energy received from the transmission signal provides the power for the PRIDs to transmit a reply signal during reception of the transmission signal. 
     The identification device  72  includes an integrated circuit chip, such as a transceiver chip, having memory storage capabilities. The integrated circuit chip can be configured to receive RF signals and to encode and store data based on the signals. During a data encoding operation each identification device  72  can be uniquely identified such that each collar  64  is also uniquely identified. This identification information is indicated by the C 1 -C 8  designations in  FIGS. 3A and 3B . In addition, the depth of each collar  64  can be ascertained using well logs, as previously explained and shown in  FIG. 1 . The depth information can then be correlated to the identification information encoded into the identification device  72 . A record can thus be established identifying each collar  64  and its true depth in the well  52 . 
     Alternately, as shown in  FIG. 3F , identification device  72 A can be in the form of an active device having a separate power source such as a battery. In addition, the identification device  72 A can include an antenna  89  for transmitting signals. Alternately, an identification device (not shown) can be configured to transmit signals through a well fluid or other transmission medium within the well  52 . Such an identification device is further described in previously cited parent application Ser. No. 09/286,650, which is incorporated herein by reference. 
     As also shown in  FIG. 3F , the identification device  72 A can be contained in a threaded mounting device  87 . The threaded mounting device  87  can comprise a rigid, non-conductive material such as a plastic. The threaded mounting device  87  is configured to be screwed into the middle portions of the casing collar  64  ( FIG. 3D ), and to be retained between adjacent tubular elements of the casing  56 . The threaded mounting device  87  includes a circumferential groove  91  for the antenna  89 , and a recess  93  for the identification device  72 A. If desired, the antenna  89  and the identification device  72 A can be retained in the groove  91  and the recess  93  using an adhesive or a suitable fastener. 
     Referring to  FIG. 3E , the reader device  70  is shown in greater detail. The reader device  70  is configured to transmit RF transmission signals at a selected frequency to the identification devices  72 , and to receive RF response signals from the identification devices  72 . As such, the reader device  70  includes a base member  77  having a transmitter  73  configured to transmit transmission signals of a first frequency to the identification devices  72 . The reader device  70  includes a receiver  71  on the base member  77  configured to receive signals of a second frequency from the identification devices  72 . 
     Preferably, the transmitter  73  is configured to provide relatively weak transmission signals such that only an identification device  72  within a close proximity (e.g., one foot) of the reader device  70  receives the transmission signals. Alternately, the antenna of the reader device  70  can be configured to provide highly directional transmission signals such that the transmission signals radiate essentially horizontally from the reader device  70 . Accordingly, the transmission signals from the reader device  70  are only received by a single identification device  72  as the reader devices passes in close proximity to the single identification device  72 . 
     In addition to the transmitter  73  and the receiver  71 , the reader device  70  includes a cover  79  made of an electrically non-conductive material, such as plastic or fiberglass. The reader device  70  also includes o-rings  75  on the base member  77  for sealing the cover  79 , and a cap member  81  attached to the base member  77  which secures the cover  79  on the base member  77 . In addition, the reader device  70  includes spacer elements  83  formed of an electrically non-conductive material such as ferrite, ceramic or plastic, which separate the transmitter  73  and the receiver  71  from the base member  77 . In the illustrative embodiment, the base member  77  is generally cylindrical in shape, and the spacer elements  83  comprise donuts with a half moon or contoured cross section. 
     Referring to  FIG. 4A , an electrical schematic for the system  50  is illustrated. As illustrated schematically, each identification device  72  includes a memory device  110 , in the form of a programmable integrated circuit chip, such as a transceiver chip, configured to receive and store identification information. As previously explained, the identification information can uniquely identify each casing collar  64  with an alpha numerical, numerical or other designator. In addition, using previously prepared well logs, the depth of each uniquely identified casing collar  64  can be ascertained. 
     As also shown in  FIG. 4A , the reader device  70  includes the transmitter  73  for transmitting transmission signals to the identification devices  72 , and the receiver  71  for receiving the response signals from the identification devices  72 . The reader device  70  can be powered by a suitable power source, such as a battery, or a power supply at the surface. In addition, the reader device  70  includes a memory device  112 , such as one or more integrated circuit chips, configured to receive and store programming information. The reader device  70  also includes a telemetry circuit  114  configured to transmit control signals in digital or other form, through software  116  to a controller  118 , or alternately to a computer  122 . 
     As is apparent the software  116  can be included in the controller  118 , or in the computer  122 . In addition, the computer  122  can comprise a portable device such as a lap top which can be pre-programmed and transported to the well site. Also, as will be further explained, the computer  122  can include a visual display for displaying information received from the reader device  70 . The controller  118 , or the computer  122 , interface with tool control circuitry  120 , which is configured to control the perforating tool  68  as required. 
     In the illustrative embodiment, the tool control circuitry  120  is in signal communication with the detonator  74  ( FIG. 3C ) of the perforating tool  68 . The tool control circuitry  120  can be located on the perforating tool  68 , on the reader device  70 , or at the surface. The reader device  70  is programmed to transmit control signals to the tool control circuitry  120 , as a function of response signals received from the identification devices  72 . For example, in the perforating process illustrated in  FIGS. 3A and 3B , coupling C 4  is located proximate to the upper level, or entry point into Zone F. Since it is desired to actuate the perforating tool  68  while it is in Zone F, the reader device  70  can be programmed to transmit actuation control signals through the tool control circuitry  120  to the detonator  74  ( FIG. 3C ), when it passes coupling C 4  and receives response signals from the identification device  72  contained in coupling C 4 . Because coupling is uniquely identified by the identification device  72  contained therein, and the depth of coupling C 4  has been previously identified using well logs, the perforating process can be initiated in real time, as the perforating tool  68  passes coupling C 4  and enters the section of the well casing  56  proximate to Zone F. 
     However, in order to insure that the detonation sequence is initiated at the right time additional factors must be considered. For example, the perforating tool  68  and reader device  70  can be transported through the well casing  56  with a certain velocity (V). In addition, the reader device  70  requires a certain time period (T 1 ) to transmit transmission signals to the identification device  72  in coupling C 4 , and to receive response signals from the identification device  72  in coupling C 4 . In addition, a certain time period (T 2 ) is required for transmitting signals to the tool control circuitry  120  and to the detonator  74  ( FIG. 3C ). Further, the charge assemblies  80  require a certain time period (T 3 ) before detonation, explosion and perforation of the casing  56  occur. All of these factors can be considered in determining which identification device  72  in which casing  64  will be used to make the reader device  70  transmit actuation control signals through the tool control circuitry  120  to the detonator  74  ( FIG. 3C ). 
     In order to provide proper timing for the detonation sequence, the velocity (V) of the perforating tool  68  and the reader device  70  can be selected as required. In addition, as shown in  FIGS. 5A and 5B , a spacer element  88  can be used to space the perforating tool  68  from the reader device  70  by a predetermined distance (D). As shown in  FIG. 5A , the perforating tool  68  can be above the reader device  70  (i.e., closer to the surface  60 ), or alternately as shown in  FIG. 5B  can be below the reader device  70  (i.e., farther from the surface  60 ). 
     As an alternative to a dynamic detonation sequence, the perforating tool  68  can be stopped when the required depth is reached, and a static detonation sequence performed. For example, the reader device  70  can be programmed to send a signal for stopping the perforating tool  68  when it reaches coupling C 6 . In this case, the signal from the reader device  70  can be used to control the wire line unit  92  and stop the wire line  90 . The detonation and explosive sequence can then be initiated by signals from the tool control circuit  120 , with the perforating tool  68  in a static condition at the required depth. 
     As shown in  FIG. 4B , signals from the reader device  70  can be used to generate a visual display  124 , such as a computer screen on the computer  122 , which is viewable by an operator at the surface. The visual display  124  is titled “True Depth Systems” and includes a power switch for enabling power to the reader device  70  and other system components. The visual display  124  also includes a “Depth Meter” that indicates the depth of the reader device  70  (or the perforating tool  68 ) within the well  52 . The visual display  124  also includes “Alarm Indicators” including a “Well Alarm Top” indicator, a “Well Alarm Bottom” indicator, and an “Explosive Device” indicator. The “Alarm Indicators” are similar to stop lights with green, yellow and red lights to indicate varying conditions. 
     The visual display  124  also includes “Power Indicators” including a “True Depth Reader” power indicator, a “True Depth Encoder” power indicator, and a “System Monitor” power indicator. In addition, the visual display  124  includes various “Digital Indicators”. For example, a “Line Speed” digital indicator indicates the speed at which the reader device  70 , and the perforating tool  68 , are being transported through the well casing  56 . An “Encoder Depth” digital indicator indicates the depth of each identification device  72  as the reader device  70  passes by the identification devices  72 . A “True Depth” indicator indicates the actual depth of the reader device  70  in real time as it is transported through the well casing  56 . 
     The visual display  124  also includes a “TDS ID” indicator that indicates an ID number for each identification device  72 . In addition, the visual display  124  includes a “TDS Description” indicator that further describes each identification device  72  (e.g., location in a specific component or zone). The visual display  124  also includes a “Time” indicator that can be used as a time drive (forward or backward) for demonstration or review purposes. Finally, the visual display  124  includes an “API Log” which indicates log information, such as gamma ray or SPE readings, from the previously described well logs, correlated to the “Digital Indicators” for depth. 
     Referring again to  FIGS. 3A and 3B , in the embodiment illustrated therein, the transport mechanism  66 W includes a wire line  90  operable by a wire line unit  92 , substantially as previously explained and shown in  FIG. 1 . The wire line  90  can comprise a slick line, an electric line, a braided line, or coil tubing. If the controller  118 , or the computer  122 , is located at the surface  60 , the wire line  90  can be used to establish signal communication between the reader device  70  and the controller  118  or the computer  122 . 
     Referring to  FIGS. 6A-6D , alternate embodiment transport mechanisms for transporting the perforating tool  68  and the reader device  70  through the casing  56  are shown. In  FIG. 6A , a transport mechanism  66 P comprises a pump for pumping a conveyance fluid through the inside diameter of the casing  56 . The pumped conveyance fluid then transports the perforating tool  68  and the reader device  70  through the casing  56 . In  FIG. 6B , a transport mechanism  66 R comprises one or more robotic devices attached to the perforating tool  68  and the reader device  70 , and configured to transport the perforating tool  68  and the reader device  70  through the casing  56 . In  FIG. 6C , a transport mechanism  66 G comprises gravity (G) such that the perforating tool  68  and the reader device  70  free fall through the casing  56 . The free fall can be through a well fluid within the casing  56 , or through air in the casing  56 . In  FIG. 6D , a transport mechanism  66 PA includes a parachute which controls the rate of descent of the perforating tool  68  and the reader device  70  in the casing  56 . Again, the parachute can operate in a well fluid, or in air contained in the casing  56 . 
     Referring to  FIGS. 7A-7C , an alternate embodiment system  50 A constructed in accordance with the invention is illustrated. The system  50 A is installed in a subterranean well  52 A, such as an oil and gas production well. In this embodiment the system  50 A is configured to perform a packer setting process in the well  52 A. 
     The well  52 A includes a well bore  54 A, and a well casing  56 A within the well bore  54 A surrounded by concrete  58 A. The well casing  56 A comprises a plurality of tubular elements  62 A, such as lengths of metal pipe or tubing, connected to one another by collars  64 A. The well  52 A extends from an earthen surface  60 A through geological formations within the earth, which are represented as Zones H and I. 
     For performing the packer setting process, the system  50 A includes a packer setting tool  68 A, an inflation device  98 A for the packer setting tool  68 A, and a reader device  70 A in signal communication with the packer setting tool  68 A. In this embodiment, the inflation device  98 A is located on the surface  60 A such that a wire, or other signal transmission medium must be provided between the packer setting tool  68 A and the inflation device  98 A. The packer setting tool  68 A can include an inflatable packer element designed for inflation by the inflation device  98 A and configured to sealingly engage the inside diameter of the casing  56 A. In  FIG. 7B , the inflatable packer element of the packer setting tool  68 A has been inflated to seal the inside diameter of the casing  56 A proximate to Zone I. 
     The system  50 A also includes a plurality of identification devices  72  ( FIG. 3D ) attached to the collars  64 A on the casing  56 A, and readable by the reader device  70 A. In addition, the system  50 A includes a transport mechanism  66 A for transporting the packer setting tool  68 A and the reader device  70 A through the well casing  56 A to Zone I. In this embodiment, the transport mechanism  66 A comprises a tubing string formed by tubular elements  102 A. As shown in  FIG. 7C , each tubular element  102 A includes a male tool joint  94 A on one end, and a female tool joint  96 A on an opposing end. This permits the tubular elements  102 A to be attached to one another to form the transport mechanism  66 A. In addition, the packer setting tool  68 A can include a central mandrel in fluid communication with the inside diameter of the transport mechanism  66 A. 
     The reader device  70 A is programmed to transmit a control signal to the inflation device  98 A upon actuation by a selected identification device  72  ( FIG. 3D ). For example, in the packer setting process illustrated in  FIGS. 7A and 7B , coupling C 4 A is located proximate to the upper level, or entry point into Zone I. Since it is desired to inflate the inflatable packer element of the packer setting tool  68 A while it is proximate to Zone I, the reader device  70 A can be programmed to transmit the control signal to the inflation device  68 A when it reaches coupling C 4 A. In this embodiment a spacer element  88 A separates the packer setting tool  68 A and the reader device  70 A. In addition, the packer setting tool  68 A is located downhole relative to the reader device  70 A. 
     In order to insure that the packer setting sequence is initiated at the right time additional factors must be considered as previously explained. These factors can include the velocity (V) of the packer setting tool  68 A and the reader device  70 A, and the time required to inflate the inflatable packer element of the packer setting tool  68 A. Alternately, the packer setting tool  68 A can be stopped at a particular coupling (e.g., coupling C 5 A) and then inflated as required. In this case the reader device  70 A can be programmed to transmit the control signals to the visual display  124  ( FIG. 4B ) on the surface  60 A when the packer tool  68 A passes a coupling  64 A at the required depth. The operator can then control the inflation device  98 A to initiate inflation of the packer setting tool  68 A. Alternately the inflation sequence can be initiated automatically by the tool control circuit  120  ( FIG. 4A ). 
     In each of the described processes the method of the invention provides an improved well. For example, in the perforating process of  FIGS. 3A and 3B , the well  52  can be perforated in the selected zone, or in a selected interval of the selected zone. Production from the well  52  is thus optimized and the well  52  is able to produce more fluids, particularly oil and gas. 
     Referring to  FIGS. 8A-8C , a multi stage operation performed in accordance with the method of the invention is illustrated. Initially, as shown in  FIG. 8A , a combination tool  130  is provided. The combination tool  134  includes a packer setting tool  132  and a perforating tool  134 , which function substantially as previously described for the packer setting tool  68 A ( FIG. 7B ), and the perforating tool  68  ( FIG. 3A ) previously described. In addition, the combination tool  134  includes the reader device  70  and the casing  56  includes identification devices  72  ( FIG. 3D ) substantially as previously described. As also shown in  FIG. 8A , the combination tool  130  is transported through the casing  56  using the gravity transport mechanism  66 G. Alternately, any of the other previously described transport mechanisms can be employed. 
     Next, as shown in  FIG. 8B , the packer setting tool  132  is actuated such that an inflatable packer element of the tool  132  seals the casing  56  at a desired depth. In this embodiment the packer setting tool  132  is a self contained unit, with an integral inflation source. As with the previously described embodiments, the reader device  70  provides control signals for controlling the packer setting tool  132 , and the packer setting process. For example, the inflatable packer element of the packer setting tool  132  can be inflated when the reader device  70  passes a selected coupling  64 , and receives a response signal from the identification device  72  contained within the selected coupling  64 . As also shown in  FIG. 8B , the perforating tool  134  separates from the packer setting tool  132  and continues to free fall through the casing  56 . 
     Next, as shown in  FIG. 8C , the perforating tool  132  is controlled such that detonation and explosive sequences are initiated substantially as previously described. Again the reader device  70  provides control signals, for controlling the perforating tool  132  to initiate the detonation and explosive sequences at the proper depth. As indicated by the dashed arrows in  FIG. 8C  explosion of the charge assemblies  80  ( FIG. 3C ) of the perforating tool  134  forms openings in the casing  58  and the concrete  58 . 
     Thus the invention provides a method and a system for performing various operations or processes in wells and for improving production from the wells. While the invention has been described with reference to certain preferred embodiments, as will be apparent to those skilled in the art, certain changes and modifications can be made without departing from the scope of the invention as defined by the following claims.