Abstract:
An apparatus includes a logging cable with exactly 3 conductors and an armor. A first transceiver is coupled to the three conductors and the armor of the logging cable. The first transceiver comprises a first-transceiver mode M 1  port, a first-transceiver mode M 2  port, and a first-transceiver mode M 3  port. The first transceiver couples to a first mode on the three conductors and the armor of the logging cable corresponding to a signal on one of the first-transceiver ports, a second mode on the three conductors and the armor of the logging cable corresponding to a signal on one of the first-transceiver ports, and a third mode on the three conductors and the armor of the logging cable corresponding to a signal on one of the first-transceiver ports. The first mode, the second mode, and the third mode are mutually orthogonal.

Description:
BACKGROUND 
       [0001]    In a multi-conductor logging cable, it is fairly easy to separate direct current (“DC”) currents simply by using separate conductors. This is because DC currents do not couple into closely adjacent conductors. However when higher frequency alternating current (“AC”) currents (such as are present in telemetry signals) are carried over the logging line, the situation is more complex because electrical conductors in close proximity over long lengths exhibit strong coupling (both capacitive and inductive) between adjacent conductors. In fact, if an AC signal is applied to a first conductor and armor at one end of a multi-conductor logging cable, measurement at the other end of about 30 thousand feet of multi-conductor cable will show that all of the signal power has transferred to adjacent conductors at certain frequencies. The exact frequency at which this power transfer takes place depends on the length of the cable as well as the type of logging cable. Such signal dropout caused by the tight mutual coupling between conductors is problematic for broadband high speed telemetry signals. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]      FIG. 1  shows a wireline well logging system. 
           [0003]      FIGS. 2A and 2B  show cross-sections of a 3-conductor logging cable. 
           [0004]      FIGS. 3-5  illustrate circuits that can be used to excite eigen modes in a 3-conductor logging cable. 
           [0005]      FIG. 6  illustrates a system that can excite a plurality of eigen modes in a 3-conductor logging cable. 
           [0006]      FIGS. 7-10  illustrate ways that different configurations of eigen mode transmission of signals can be used. 
           [0007]      FIG. 11  illustrates an environment. 
       
    
    
     DETAILED DESCRIPTION 
       [0008]    In one embodiment of a wireline well logging system  100  at a well site, as depicted in  FIG. 1 , a logging truck or skid  102  on the earth&#39;s surface  104  houses a data gathering computer  106  and a winch  108  from which a logging cable  110  extends into a well bore  112  drilled into a formation  114 . 
         [0009]    In one embodiment, the logging cable  110  suspends a logging toolstring  116  within the well bore  112  to measure formation data as the logging toolstring  116  is raised or lowered by the logging cable  110 . In one embodiment, the logging toolstring  116  is conveyed into the well bore  112  by coiled tubing (not shown). In one embodiment, in which the well bore  112  is a deviated well, the logging toolstring  116  is conveyed into the well bore  112  by a tractor (not shown). In one embodiment, the logging toolstring  116  includes a variety of sensors and actuators, such as sensor  118 , sensor  119 , and sensor  120 . 
         [0010]    In one embodiment, in addition to conveying the logging toolstring  116  into the well, the logging cable  110  provides a link for power and communications between the surface equipment, e.g., data gathering computer  106 , and the logging toolstring  116 . 
         [0011]    In one embodiment, as the logging tool  116  is raised or lowered within the well bore  112 , a depth encoder  122  provides a measured depth of the extended cable  110 . In one embodiment, a tension load cell  124  measures tension in the logging cable  110  at the surface  104 . 
         [0012]    The AC coupling between conductors described above may be reduced on the order of 1000 times over all frequencies by using symmetrical sets of conductors to conduct the desired AC currents. In one embodiment, the logging cable  110  with symmetrical conductors, shown in cross-section in  FIG. 2A , includes three conductors  202 . In one embodiment, each of the conductors  202  is surrounded by an insulating jacket  204 . The insulated conductors are bundled together in a semiconductive wrap  205 , which is surrounded by two layers of counterwound metal armor wire  206 . Being made of metal, the armor wires  206  are conductive and may be used as a fourth conductor.  FIG. 2B  shows a cross-section of the logging cable  110  of  FIG. 2A  having its conductors labeled  1 - 3  and its armor labeled A. In one embodiment, the properties of the cable conductors are well matched so that the difference between the resistance of any conductor with respect to any other conductor is less than 2%. Additionally, in one embodiment the capacitance of any conductor to armor does not vary from the capacitance of any other conductor to armor by more than 2% The notations used in  FIG. 2B  will be used in the following discussions. 
         [0013]    A 3-conductor logging cable, such as that shown in  FIGS. 2A and 2B , could be advantageous over the more commonly-used 7-conductor cable such as that illustrated in U.S. Pat. No. 7,081,831, in situations in which the slenderness of the 3-conductor logging cable is preferable. For example, a 3-conductor cable might be preferred in a slickline operation where slender cables are useful but it is also desired to power down-hole motors from the surface. 
         [0014]    Choosing symmetrical sets of conductors to pass electrical currents is known as mode transmission. Mode transmission is based on determining the eigenvectors or the proper symmetrical set of conductors which will pass signal and/or power currents over a multi-conductor logging line. Generally for a multi-conductor logging line with N conductors equally spaced from the center of the cable, such as logging cable  110  shown in  FIGS. 2A and 2B , there are N symmetrical connections that provide N independent paths for AC signals. Usually only one of these paths is a direct connection to the electrical conductors. This single “direct connection” path can be used to provide AC or DC power from the surface to the downhole equipment or it can be used to provide a telemetry connection between the surface equipment, e.g., data gathering computer  106 , and the tools below, e.g. sensors  118 ,  119 ,  120 . 
         [0015]    Eigen mode transmission involves superimposing several signals on each of the conductors of a multi-conductor cable. For a 3-conductor cable the three vertical columns in Table 1 define an acceptable set of orthogonal eigen functions for power &amp; telemetry transmission. 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Mode 1 
                 Mode 2 
                 Mode 3 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Conductor 1 
                 1 
                 1 
                 −1 
               
               
                   
                 Conductor 2 
                 1 
                 −1 
                 −1 
               
               
                   
                 Conductor 3 
                 1 
                 0 
                 +2 
               
               
                   
                   
               
             
          
         
       
     
         [0016]    It can be seen that the dot product of the Mode  1  (column 1) with Mode  2  (column 2) is zero; similarly the dot product of the Mode  2  (column 2) with Mode  3  (column 3) is zero, and the dot product of the Mode  1  (column 1) with Mode  3  (column 3) are both zero. Thus, the vectors represented by these columns are mutually orthogonal to each other. 
         [0017]    In one embodiment, Mode  1  , called the “common” mode, is excited by the circuit shown in  FIG. 3 . In one embodiment, a source  302 , which could be an AC power source, a DC power source, or a telemetry signal source, is coupled through a 3-conductor logging cable  304  to a load  306 . In one embodiment, the 3-conductor logging cable  304  includes three conductors ( 1 ,  2 , and  3 ) and an armor arranged as shown in  FIGS. 2A and 2B . In one embodiment, one leg of the source  302  is tied to all three conductors and the other leg is tied to the armor. As a result, the source  302  excites Mode  1  in the logging cable  304  as shown in Table 1 above. 
         [0018]    In one embodiment, Mode  2  is excited by the circuit in  FIG. 4 . In one embodiment, a source  402 , which could be an AC power source, a DC power source, or a telemetry signal source , is coupled through a 3-conductor logging cable  404  to a load  406 . In one embodiment, the 3-conductor logging cable  404  includes three conductors ( 1 ,  2 , and  3 ) and an armor arranged as shown in  FIGS. 2A and 2B . In one embodiment, one leg of the source  402  is tied to conductor  1  and the other leg is tied to conductor  2 . The source  402  is not tied to conductor  3  or to the armor. As a result, the source  402  excites Mode  2  in the logging cable  304  as shown in Table 1 above. 
         [0019]    In one embodiment, Mode  3  is excited by the circuit in  FIG. 5 . In one embodiment, a −V DC source  501  and a +2V DC source  502  are coupled through a 3-conductor logging cable  504  to a load  506 . In one embodiment, the 3-conductor logging cable  404  includes three conductors ( 1 ,  2 , and  3  ) and an armor arranged as shown in  FIGS. 2A and 2B . In one embodiment, the −V DC source  501  is coupled to conductor  1  and conductor  2  and the +2V DC source  502  is coupled to conductor  3 . In one embodiment, one leg of the load  506  is coupled to conductor  1  and conductor  2  and the other leg of the load  506  is coupled to conductor  3 . As a result the DC sources  501  and  502  excite Mode  3  in the logging cable  404  as shown in Table 1 above. 
         [0020]    The challenge is to connect the circuits shown in  FIGS. 3 ,  4 , and  5  simultaneously. 
         [0021]    In one embodiment, the simultaneous connections are accomplished through the use of multifilar transformers. Multifilar transformers are manufactured with multiple secondary windings with exactly the same number of turns. Thus, in one embodiment, using a multifilar transformer with four secondary windings, mode  3  is excited by connecting the negative end of secondary winding  1  to conductor  1 , the negative end of secondary winding  2  to conductor  2 , and the positive end of the series connection of secondary winding  3  and secondary winding  4  (to give a weight of 2) to conductor  3 . In one embodiment, the positive end of secondary winding  1  and the positive end of secondary winding  2  connect to the negative end of the series combination of secondary winding  3  and secondary winding  4 . 
         [0022]    In one embodiment, shown in  FIG. 6 , a circuit uses multifilar transformers to provide the eigen modes shown in Table 1 over a 3 conductor logging cable.  FIG. 6  illustrates surface equipment to the left of dashed line  602  and downhole equipment to the right of dashed line  602 . 3-conductor logging cable  604  connects the surface equipment to the downhole equipment. 
         [0023]    In one embodiment, the circuit in  FIG. 6  allows bi-directional communication. That is, the equipment on the surface can transmit information to the downhole equipment and the downhole equipment can transmit information to the surface equipment. In one embodiment, the equipment on the surface transmits in one mode (e.g., mode M 3 ) while the downhole equipment transmits in another mode (e.g., mode M 2 ) and power is delivered from the surface to the downhole equipment in yet another mode (e.g., mode M 1 ). 
         [0024]    In one embodiment, the 3-conductor logging cable  604  shown in  FIG. 6  includes 3 conductors (conductor  1 , conductor  2 , and conductor  3  ) and an armor arranged as shown in  FIGS. 2A and 2B . In one embodiment, the surface equipment includes a first multifilar transformer  606  that includes a primary winding  606 P and three secondary windings  606 S 1 ,  606 S 2 , and  606 S 3 . In one embodiment, two of the secondary windings  606 S 2  and  606 S 3  are connected in series. In one embodiment, the polarity of secondary winding  606 S 1  (indicated by the dot adjacent the winding) is opposite the polarity of the combined secondary windings  606 S 2  and  606 S 3 . 
         [0025]    In one embodiment, the surface equipment also includes a second multifilar transformer  608  that includes a primary winding  608 P and two secondary windings  608 S 1  and  608 S 2 . In one embodiment, the polarity of secondary winding  608 S 1  is opposite the polarity of secondary winding  608 S 2 . 
         [0026]    In one embodiment, when the surface equipment is transmitting in the M 3  mode, the signal present on the primary winding  606 P of multifilar transformer  606  (i.e., at the M 3  port) will appear across secondary winding  606 S 1  with a polarity −P and a first amplitude A, depending on the amplitude of the signal present on the primary winding  606 P and the ratio of the number of turns in secondary winding  606 S 1  to the number of turns in primary winding  606 P (in one embodiment, the ratio is 1). That signal will appear at conductors  1  and  2  through the secondary windings of multifilar transformer  608  (discussed below) at the same amplitude A and polarity P, although the current exiting the secondary winding  606 S 1  will be divided between conductor  1  and conductor  2 . In one embodiment, the signal present on the primary winding  606 P of multifilar transformer  606  (i.e., at the M 3  port) will appear across series-connected secondary windings  606 S 2  and  606 S 3  (and therefore at conductor  3  of the 3-conductor logging cable  604  relative to the armor) with amplitude  2 A and polarity +P. Normalizing the outputs by dividing by A and representing the outputs as a vector according to (conductor  1 , conductor  2 , and conductor  3 ) results in (−1, −1, +2), which is mode M 3  in Table 1 above. 
         [0027]    In one embodiment, when the surface equipment is receiving in the M 3  mode, the current in the signal present on conductor  1  is summed with the current in the signal present on conductor  2  through the secondary windings of multifilar transformer  608  (discussed below) and passes through secondary winding  606 S 1  of multifilar transformer  606 . In one embodiment, the mode M 3  voltages present on conductor  1  and conductor  2  are in parallel across the secondary winding  606 S 1  of multifilar transformer  606 . Thus, in one embodiment, the voltage across the primary  606 P is the voltage present on conductor  1  (or conductor  2 ) adjusted by the turn ratio of the  606 P/ 606 S 1  portion of multifilar transformer  606 . 
         [0028]    Further, the signal on conductor  3  will appear across the combined windings of secondary windings  606 S 2  and  606 S 3 , causing a contribution to the signal across primary winding  606 P to be one-half of the signal present on conductor  3 . 
         [0029]    In one embodiment, when the surface equipment is transmitting in the M 2  mode, the signal present on the primary winding  608 P of multifilar transformer  608  (i.e., at the M 2  port) will appear across secondary winding  608 S 1  (and therefore at conductor  1  of the 3-conductor logging cable  604  relative to the armor) with a second amplitude B (which in one embodiment is equal to first amplitude A), depending on the amplitude of the signal present on the primary winding  608 P and the ratio of the number of turns in secondary winding  608 S 1  to the number of turns in primary winding  608 P (in one embodiment, the ratio is 1), and a polarity +P. In one embodiment, the signal present on the primary winding  608 P of multifilar transformer  608  (i.e., at the M 2  port) will appear across secondary winding  608 S 2  (and therefore at conductor  2  of the 3-conductor logging cable  604  relative to the armor) with amplitude B and polarity −P. Normalizing the outputs by dividing by B and representing the outputs as a vector according to (conductor  1 , conductor  2 , and conductor  3 ) results in (1, −1, 0), which is mode M 2  in Table 1 above. 
         [0030]    In one embodiment, when the surface equipment is receiving in the M 2  mode, the signal present on conductor  1  of the 3-conductor logging cable  604  will be present on the primary  608 P adjusted by the turn ratio of the  608 P/ 608 S 1  portion of multifilar transformer  608 . In one embodiment, the signal present on conductor  2  of the 3-conductor logging cable  604  will be present on the primary  608 P adjusted by the turn ratio of the  608 P/ 608 S 2  portion of multifilar transformer  608 . In one embodiment, the signal received on conductor  2  is an inverted version of the signal received on conductor  1  so that the effect of multifilar transformer  608 , in which secondary winding  608 S 2  has the opposite polarity of secondary winding  608 S 1 , is that the same signal will appear on primary  608 P. 
         [0031]    In one embodiment, the surface equipment includes power source  612 , which can be an AC power source or a DC power source. In one embodiment, one leg of the power source  612  is connected through multifilar transformers  606  and  608  to all three conductors of the 3-conductor logging cable  604 . In one embodiment, the other leg of the power source  612  is connected to the armor. Representing these connections as a vector according to (conductor  1 , conductor  2 , and conductor  3 ) results in (1, 1, 1), which is mode M 1 in Table 1 above. 
         [0032]    In one embodiment, the downhole equipment includes a complementary set of multifilar transformers  614  and  616 . In one embodiment, multifilar transformer  614  includes a primary winding  614 P and two secondary windings  614 S 1  and  614 S 2 . In one embodiment, the two secondary windings  614 S 1  and  614 S 2  are coupled to conductor  1  and conductor  2 , respectively, of the 3-wire logging cable  604 . 
         [0033]    In one embodiment, when the downhole equipment is transmitting in the M 3  mode, the signal present on the primary winding  616 P of multifilar transformer  616  (i.e., at the M 3  port) will appear across secondary winding  616 S 1  with a polarity −P and a first amplitude A, depending on the amplitude of the signal present on the primary winding  616 P and the ratio of the number of turns in secondary winding  616 S 1  to the number of turns in primary winding  616 P (in one embodiment, the ratio is 1). That signal will appear at conductors  1  and  2  through the secondary windings of multifilar transformer  614  (discussed below) at the same amplitude A and polarity P, although the current exiting the secondary winding  616 S 1  will be divided between conductor  1  and conductor  2 . In one embodiment, the signal present on the primary winding  616 P of multifilar transformer  616  (i.e., at the M 3  port) will appear across series-connected secondary windings  616 S 2  and  616 S 3  (and therefore at conductor  3  of the 3-conductor logging cable  604  relative to the armor) with amplitude 2A and polarity +P. Normalizing the outputs by dividing by A and representing the outputs as a vector according to (conductor  1 , conductor  2 , and conductor  3 ) results in (−1, −1, +2), which is mode M 3  in Table 1 above. 
         [0034]    In one embodiment, when the downhole equipment is receiving in the M 3  mode, the current in the signal present on conductor  1  is summed with the current in the signal present on conductor  2  through the secondary windings of multifilar transformer  614  (discussed below) and passes through secondary winding  616 S 1  of multifilar transformer  616 . In one embodiment, the mode M 3  voltages present on conductor  1  and conductor  2  are in parallel across the secondary winding  616 S 1  of multifilar transformer  616 . Thus, in one embodiment, the voltage across the primary  616 P is the voltage present on conductor  1  (or conductor  2  ) adjusted by the turn ratio of the  616 P/ 616 S 1  portion of multifilar transformer  616 . 
         [0035]    Further, the signal on conductor  3  will appear across the combined windings of secondary windings  616 S 2  and  616 S 3 , causing a contribution to the signal across primary winding  616 P to be one-half of the signal present on conductor  3 . 
         [0036]    In one embodiment, when the downhole equipment is transmitting in the M 2  mode, the signal present on the primary winding  614 P of multifilar transformer  614  (i.e., at the M 2  port) will appear across secondary winding  614 S 1  (and therefore at conductor  1  of the 3-conductor logging cable  604  relative to the armor) with a second amplitude B (which in one embodiment is equal to first amplitude A), depending on the amplitude of the signal present on the primary winding  614 P and the ratio of the number of turns in secondary winding  614 S 1  to the number of turns in primary winding  614 P, and a polarity +P. In one embodiment, the signal present on the primary winding  614 P of multifilar transformer  614  (i.e., at the M 2  port) will appear across secondary winding  614 S 2  (and therefore at conductor  2  of the 3-conductor logging cable  604  relative to the armor) with amplitude B and polarity −P. Normalizing the outputs by dividing by B and representing the outputs as a vector according to (conductor  1 , conductor  2 , and conductor  3 ) results in (1, −1, 0), which is mode M 2  in Table 1 above. 
         [0037]    In one embodiment, when the downhole equipment is receiving in the M 2  mode, the signal present on conductor  1  of the 3-conductor logging cable  604  will be present on the primary  614 P adjusted by the turn ratio of the  614 P/ 614 S 1  portion of multifilar transformer  614 . In one embodiment, the signal present on conductor  2  of the 3-conductor logging cable  604  will be present on the primary  614 P adjusted by the turn ratio of the  614 P/ 614 S 2  portion of multifilar transformer  614 . In one embodiment, the signal received on conductor  2  is an inverted version of the signal received on conductor  1  so that the effect of multifilar transformer  614 , in which secondary winding  614 S 2  has the opposite polarity of secondary winding  614 S 1 , is that the same signal will appear on primary  614 P. 
         [0038]    In one embodiment, the power transmitted from the surface equipment in mode M 1  appears across a load  618 . The currents delivered on conductors  1  and  2  are summed through multifilar transformer  614  and the result is summed with the current delivered on conductor  3  through multifilar transformer  616 . The combined currents pass through the load  618  and return to the surface through the armor of the 3-conductor logging cable  604 . 
         [0039]    In effect, the transformation of signals present on the surface equipment M 3  port by multifilar transformer  606  into mode M 3  signals is “undone” by the transformation performed by multifilar transformer  616  so that the original signals appear on the downhole equipment M 3  port. Similarly, the transformation of signals present on the downhole equipment M 3  port by multifilar transformer  616  into mode M 3  signals is “undone” by the transformation performed by multifilar transformer  606  so that the original signals appear on the surface equipment M 3  port. 
         [0040]    In effect, the transformation of signals present on the surface equipment M 2  port by multifilar transformer  608  into mode M 2  signals is “undone” by the transformation performed by multifilar transformer  614  so that the original signals appear on the downhole equipment M 2  port. Similarly, the transformation of signals present on the downhole equipment M 2  port by multifilar transformer  614  into mode M 2  signals is “undone” by the transformation performed by multifilar transformer  608  so that the original signals appear on the surface equipment M 2  port. 
         [0041]    As can be seen in  FIGS. 7-10 , in one embodiment the 3-conductor logging cable  604  can be used in a number of configurations. Even assuming that mode M 1  is devoted to the transmission of power, modes M 2  and M 3  provide a number of alternative data transmission schemes. In one embodiment shown in  FIG. 7 , mode M 3  is used to transmit data from the surface equipment to the downhole equipment and mode M 2  is used to transmit data from the downhole equipment to the surface equipment. In one embodiment shown in  FIG. 8 , mode M 2  is used to transmit data from the surface equipment to the downhole equipment and mode M 3  is used to transmit data from the downhole equipment to the surface equipment. In one embodiment shown in  FIG. 9 , in which there is excessive noise on the 3-conductor logging cable  604 , both modes M 2  and M 3  are used to transmit data from the surface equipment to the downhole equipment. In one embodiment shown in  FIG. 10 , in which it is desired to increase the reliability of data transmission from the downhole equipment to the surface equipment, both modes M 2  and M 3  are used for that purpose. In one embodiment (not shown), mode M 3 , in addition to being used for transmission of power, is also used to transmit data between the surface equipment and the downhole equipment. In one embodiment (not shown), either mode or both modes M 2  and M 3  simultaneously transmit data bi-directionally between surface and downhole over  3  conductor logging cable  604 . 
         [0042]    In one embodiment, use of the three transmission modes may be changed depending on the environment in which the surface equipment and the downhole equipment are operating. In one embodiment, an environmental measuring device is used to monitor the environment and a controller makes a selection of the transmission mode configuration using outputs from the environmental measuring device. 
         [0043]    For example, in one embodiment shown in  FIG. 6  a downlink  620  includes data, such as commands for downhole equipment, to be transmitted from the surface equipment to the downhole equipment. In one embodiment, an uplink  622  includes data, such as sensor data collected downhole, to be transmitted from the downhole equipment to the surface equipment. In one embodiment, a switch  624  provides the ability to selectively connect the downlink  620  to the M 2  port and/or the M 3  port (in one embodiment, the switch  624  also provides connectivity to the M 1  input). In one embodiment, the switch  624  provides the ability to selectively connect the uplink  622  to the M 2  port and/or the M 3  port. 
         [0044]    In one embodiment, a controller  626  sends commands to the switch  624  to configure it. In one embodiment, an environmental measuring device  628 , such as a bit error rate detector, measures the bit error rate (“BER”) on the uplink  622  and provides a BER statistic to the controller  626 , which then configures the switch to improve the BER. In one embodiment, the controller  262  may be commanded by the data gathering computer  106  through a data link (not shown). 
         [0045]    In one embodiment, in the downhole equipment a downlink  630  includes the data transmitted by the surface equipment via the downlink  620 . In one embodiment, an uplink  632  includes the data received by the surface equipment as the uplink  622 . In one embodiment, a switch  634  provides the ability to selectively connect the downlink  630  to the M 2  port and/or the M 3  port (in one embodiment, the switch  634  also provides connectivity to the M 1  input). In one embodiment, the switch  634  provides the ability to selectively connect the uplink  632  to the M 2  port and/or the M 3  port. 
         [0046]    In one embodiment, a controller  636  sends commands to the switch  634  to configure it. In one embodiment, an environmental measuring device  638 , such as a bit error rate detector, measures the bit error rate (“BER”) on the downlink  630  and provides a BER statistic to the controller  636 , which then configures the switch to improve the BER. In one embodiment, the controller  636  is commanded by the surface equipment controller  626  or by the data gathering computer  106 . 
         [0047]    In one embodiment, shown in  FIG. 11 , the surface equipment controller  626  and/or the downhole equipment controller  636  is controlled by software in the form of a computer program on a non-transitory computer readable media  1105 , such as a CD, a DVD, a USB drive, a portable hard drive or other portable memory. In one embodiment, a processor  1110 , which may be the same as or included in the surface equipment controller  626 , the downhole equipment controller  636 , or the data gathering computer  106 , reads the computer program from the computer readable media  1105  through an input/output device  1115  and stores it in a memory  1120  where it is prepared for execution through compiling and linking, if necessary, and then executed. In one embodiment, the system accepts inputs through an input/output device  1115 , such as a keyboard or keypad, mouse, touchpad, touch screen, etc., and provides outputs through an input/output device  1115 , such as a monitor or printer. In one embodiment, the system stores the results of calculations in memory  1120  or modifies such calculations that already exist in memory  1120 . 
         [0048]    In one embodiment, the results of calculations that reside in memory  1120  are made available through a network  1125  to a remote real time operating center  1130 . In one embodiment, the remote real time operating center  1130  makes the results of calculations available through a network  1135  to help in the planning of oil wells  1140  or in the drilling of oil wells  1140 . 
         [0049]    The word “coupled ”herein means a direct connection or an indirect connection. 
         [0050]    The text above describes one or more specific embodiments of a broader invention. The invention also is carried out in a variety of alternate embodiments and thus is not limited to those described here. The foregoing description of an embodiment of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not by this detailed description, but rather by the claims appended hereto.