Abstract:
An apparatus and related method for detecting oil and mineralized water, if it exists, in a well. The apparatus comprises a sensor assembly for placing down the well, the sensor assembly having a float therein that rises when fluid is detected and adapted to close an electrical contact of a circuit having a power source. The apparatus also has a base assembly used for raising and lowering the sensor assembly into and out of the well. An alarm is electrically coupled to the circuit that includes the sensor assembly and power source, the alarm operable to indicate when the electrical contact is closed.

Description:
TECHNICAL FIELD 
   The present invention relates to apparatus and methods used in the recovery of oil in oil producing fields. 
   BACKGROUND 
   Stripper wells are oil or gas wells that are either non-producing or yield very little oil, generally less than three barrels a day. Because of their low yield, these wells are often abandoned due to the cost to recover the oil. Over time, however, these wells often can recover so that, often for a limited time, oil can be once again be extracted from the well. Many times these wells are often sold or leased in hopes of recovering oil that may have accumulated in the wells. Several techniques have been developed for extracting oil in these wells. They include placing pump jacks having timers set to operate the pump at known oil recovery intervals. Conventional recovery devices include bailers and air jets techniques. Each of these techniques has the disadvantage that each is unable to determine the depth at which oil resides in the well, and the amount of recoverable oil in the well. 
   Before these recovery techniques are used it would be advantageous to determine the depth at which oil can be found in the well, and if there is mineralized water present, at what depth such mineralized water exists. This information could be used to determine how much oil is available to recover and to evaluate whether it is worth recovering. 
   SUMMARY OF THE INVENTION 
   The present invention comprises an apparatus and method for determining the amount of fluids, such as oil and mineralized water, in a well by determining the depth where the top of the fluid in the well resides and the depth where the oil sits on top of mineralized water, if it is present in the well. 

   
     DESCRIPTION OF THE FIGURES 
     The foregoing and other objects and advantages of the invention will become clearer with reference to the following detailed description as illustrated by the drawings in which: 
       FIG. 1  is a first view of the apparatus of the present invention comprising a sensor assembly and a base assembly used to detect oil and/or mineralized water in a well; 
       FIG. 2  is the base assembly shown in  FIG. 1  from a different view; 
       FIG. 3  is a circuit diagram used to illustrate the electrical operation of the apparatus of the present invention; 
       FIG. 4  is an enlarged view of the wiper shown in  FIG. 1  for illustrating its components used to wipe the cable clean as it is pulled from the well; 
       FIG. 5  is a schematic diagram used to illustrate the components of the sensor assembly; 
       FIG. 6  is a partial schematic diagram of the sensor assembly of  FIG. 5  showing one leg being biased by a spring for making electrical contact with the interior wall of a well. 
   

   DETAILED DESCRIPTION 
   The device and method described below enables the user to determine the amount of oil in a well, even when mineralized water is present. It does so by determining the top of the oil column in the well, and the level of mineralized water, if it is present. Once this is known, the amount of oil in the well can be easily calculated. Knowing how much oil is present in the well greatly aids in the cost calculations to determine whether the cost to recover the oil is feasible. 
   Referring now to  FIG. 1 , an interface tool  10  used to determine the oil and mineralized water levels in the well is illustrated. Generally this tool includes two components, an interface sensor assembly  12  and a base assembly  14 . The interface sensor assembly  12 , which will be discussed in greater detail below with reference to  FIG. 3 , consists of a sensor assembly  16  and a sensor stand  18  used to guide the sensor assembly  16  into and out of a well  20 . 
   The base assembly  14 , as shown in  FIGS. 1 and 2 , generally includes a spool of cable  22  that is mounted on a frame  24 , preferably two gear/chain drive assemblies  26 ,  28 , and electric motor/gear box combination  30 ,  32 , an alarm  34 , and a hand held control module  36 . To protect the base assembly  14 , a cover  38  is placed over the base assembly and an eyelet  40  is provided to help lift and move the device, if necessary to another well. 
   The cable  42  serves two purposes. It is used to lower and raise the sensor assembly  16  into and out of the well  20  and to provide electric current to the sensor assembly  16 . Preferably, the cable  42  is a single multi-strand cable coated with a nylon or similar coating, which electrically insulates it. One skilled in the art would appreciate that a variety of gauged cables are available and could be used. The cable needed will depend on power requirements of the interface tool  10  and the weight and/or resistance expected when pulling the sensor from the well. The size of the spool  22  will depend on the length of the cable  42 , which should be sufficient enough to allow the sensor assembly  16  to reach the bottom of the well  20 . The rotation of the spool of cable  22  is driven by the electric motor/gear box combination  30 ,  32 , which may also be mounted on the frame  24 . The gearbox  32  is shown driving the spool  22  using the gear/chain drive assembly  26 . Alternatively, the gearbox could be eliminated and the motor could be directly connected to the spool. Eliminating the gearbox would be dependant on the size and weight of the spool. Also, a gas motor could be used instead of the electric motor. 
   A level wind  44  is provided to help to ensure an even distribution of the cable  42  on the spool  22  as it is rewound. The level wind  44  primarily consists of a worm gear  46  (as seen in  FIG. 2 ) driven by a gear/chain drive assembly  28  connected to the spool  22 . As the spool  22  rotates, it rotates the worm gear  46  and drives a cable guide  48 , which consists of a follower  50  that has a pin (not shown) that traverses back and forth across grooves of the worm gear  46 . Two roll bars  54 ,  56  extending from the follower  50  and vertically upward as shown to assist the cable  42  to continuously wind evenly on the spool  22 . Level winds of the type described are commonly available. One skilled in the art would appreciate that choosing the appropriate level wind would depend on the speed of the rotating spool and size of cable. 
   The interface tool  10  is controlled by the hand held control module  58  and is illustrated as having three switches,  60 ,  62 , and  64 . One switch  60  is used to control the main power to the interface tool  10 . The second switch  62  controls the up and down direction of the sensor assembly  16  in the well  20  and the third switch is used for turning on and off power to the cable  42 . The control module  58  is connected to an outside source of power (not shown) at an electrical box  66 , which houses various electrical connections that are described herein. Preferably, wires  68 , connecting the hand held module  58  to the interface tool, are long enough to comfortably allow a user to stand next to the interface sensor assembly  12  to monitor the progress of the sensor assembly  16  into and out of the well  20 . Generally a circuit is formed by the outside source of power, the cable  42 , the sensor assembly  16 , and the alarm  34 . The alarm  34 , which may be a horn, light, buzzer, strobe or siren or other suitable indicator, is used to indicate when either mineralized water or oil is detected. This circuit is illustrated in  FIG. 3 . Power is delivered to the sensor assembly  16  by electrically connecting the end of the cable  42  wrapped around the axle of the spool  22  to a commonly available armature system with brushes  70  ( FIGS. 1 and 2 ). This armature system is connected to the hot terminal of the external power source. As will be described in more detail below, under certain circumstances, if the sensor assembly  16  detects oil or mineralized water, then the sensor assembly  16  is adapted to close a switch to a circuit including the power supply and alarm. To complete the circuit, the sensor assembly  16  is electrically in contact with the inner casing of the well  20  (as will be discussed in greater detail below) and a ground wire  72  connects the well to the hot terminal of the alarm  34 . (Also see  FIG. 1 ). The other terminal of the alarm is connected to the common terminal of the power source. In the present embodiment 24 volts AC is used to power the alarm, but other voltages could be used. 
   The stand assembly  18  of the interface sensor assembly  12  is placed over and mounted  25  to the well as shown in  FIG. 1 . The stand assembly  18  is preferably mounted to the top of the well housing using three clamps  74  arranged in a tripod configuration (only one clamp is shown) to secure it to the top of the well. These clamps are preferably made of electrically conductive material. An arm  76  extending over the well  20 , as shown, is used to support and assist the sensor assembly  16  into and out of the well  20 . Two rollers  78 ,  80  are mounted on the arm  76  and are used for supporting the cable  42  as shown. A cable counter  82  is also provided to measure the length of cable as it is lowered into the well and identify the depth at which the alarm goes off, indicating oil or mineralized water. Such counters are commonly available and could be mounted to the top roller to count the revolutions that it makes to give an indication of the length of the cable. Since the sensor assembly  16  will be placed in oil, a wiper  84 , shown more clearly in  FIG. 4 , may also be provided to wipe the cable  42  clean from oil before it is rewound onto the spool  22 . The wiper  84  is preferably mounted to the arm by a bracket  77  and is comprised of a wiper housing  85  supported by the bracket  77 . A cap  87  is used to compress a piece of felt  89  placed in a cavity  91  in the wiper housing  85  and around the cable  42 . A nut and bolt assembly  93  could be used to adjust the tension placed on the cable  42 . 
   Referring now to  FIG. 5 , the cable  42  is connected to the interface sensor assembly  16  by allowing it to feed through the top of a nosepiece  86  of the sensor assembly  16  and into an interior cavity  88  formed therein as shown. A port  90  is provided to allow fluid to enter or exit the cavity  88 . The cable  42  is preferably attached to the nosepiece  86  by a copper terminal  92  crimped at the end of the cable  42 . However, other methods for connecting the cable to the nosepiece could be employed as would be appreciated by one skilled in the art. A plastic insulator  94  is provided to electrically insulate the end of the cable  42  in the cavity from the nosepiece  86 . Preferably the nosepiece and the housing are made of electrically conductive non-corrosive material such as stainless steel. 
   In addition to coupling the sensor assembly  16  to the cable in the manner described above, the end of the cable acts as an electrical contact  96  for a floating ground rod  98 . The floating ground rod  98  consists of a metal rod attached to a float  100  that is basically a hollow cup like container that is allowed to freely float in a float chamber  102  of the sensor assembly  16 . The float  100  is guided up and down in the float chamber  102  by the ground rod  98 , which extends from the bottom of the float upward through a plate  104  attached to the nosepiece  86  and downward through a hole  106  in the base  107  of the sensor assembly  16 . The plate  104  has a centering hole  108  sized for allowing the rod  98  to freely slide back and forth as the float  100  rises and falls within the float chamber  102 . Other holes  110  are provided in the plate to allow fluid to enter or exit the cavity  88 . Similarly the hole  106  in the base is sized to allow the rod  98  to only slide up and down. The floating ground rod  98  is also connected to the base  107  of the sensor assembly  16  by a wire  112  that is allowed to flexibly travel with the float  100  as it rises and falls with the presence of fluid in the float chamber  102 . 
   The base  107  of the sensor assembly  16  is equipped with three legs  114  having rollers  116  at the end of the legs as shown. These rollers  114  are preferably biased so as to exert pressure against the interior diameter of the well  20  in order to make electrical contact with the well casing when the sensor assembly  16  is placed down in the well  20 . Preferably, the rollers  116  are ground to points, as shown, to help cut through potential build up of material that may have coated the well when oil was pumped from the well in the past or from corrosion formed on the interior diameter of the well casing. One-way of ensuring electrical contact is to spring load the legs  114  so that they push outward and against the interior well housing. As shown in  FIG. 6 , this can be accomplished by cutting a channel  118  in the base  107  of the sensor housing and mounting the legs  114  (only one is shown) so that a short end of each of the legs is cantilevered in the channel  118 . This short end of the leg can be drawn into the channel by wrapping an elastic material such as a spring  122  around the short end of the leg  120  thereby biasing the long end of the leg  114  and hence the roller against the inner wall of the well. It should be understood by those skilled in the art that other techniques could also be employed to accomplish the same function. 
   The operation of the interface tool  10  will now be described. When the sensor assembly  16  is sent down into the well the power is turned on thereby electrically connecting one side of the potential of the power source to the sensor assembly  16 . As the sensor assembly  16  descends into the well  20 , the float  100  remains at rest at the bottom of the float chamber  102 , keeping the circuit from being completed. Once fluid is encountered in the well  20 , it enters the holes  126  in the float chamber  102  thereby filling it. Air in the chamber escapes through the port  90  in the nosepiece  86 . As fluid collects in the float chamber  102 , the float  100  begins to rise until the ground rod  98  makes contact with the end of the cable  96 . When electrical contact is made, the circuit is completed and alarm  34  turns on. As the float chamber  102  continues to fill, fluid pours over into the float  100  (as indicated by arrow  128  of  FIG. 5 ) and it begins to sink, breaking the electrical contact between the rod  98  and the end of the cable  96 . Depending on which fluid fills the sensor, the alarm will turn on and then shortly thereafter turn off or it will stay on. If oil fills the float chamber  102  and then the cavity  88 , the float  100  will sink and the electrical contact will be broken. As a result the alarm  34  will turn off because oil serves as an insulator breaking the electrical contact between the ground rod  98  and the end of the cable  96 . If it is mineralized water filling the cavity  88 , the alarm will remain on if the mineralized water is a conductor, as is the case with most mineralized water, such as saltwater that is found in wells. Since oil has less density than mineralized water, it should be appreciated to one skilled in the art that the mineralized water will replace the oil in the cavity and make an electrical contact between the end of the cable and the ground rod. Thus, the user of this device is able to tell whether the sensor assembly  16  is in oil or mineralized water depending on whether the alarm  34  stays on or shortly thereafter goes off. If the alarm  34  is initially activated and then deactivated, that indicates that the sensor is passing through oil. The level of the mineralized water is found by allowing the sensor assembly  16  to continue down the well until the alarm  34  is activated again and remains on. Once float  100  is full, and it is determined to be in oil, the sensor assembly  16  can be pulled up just out of the oil, such that float  100  drains (via aperture  127 ), then the sensor assembly  100  can be jogged down to determine a more accurate reading of the level of the top of the oil. This allows the user to find such level without bringing the sensor assembly  16  to the surface and dumping the float and then starting the process over. Note, fluid is able to exit float  100  through small aperture  127  located proximate the bottom of the float. Because the volume of fluid exiting at aperture  127  is small in relation to the amount of fluid entering float  100  (as seen at arrow  128 ), it has minimal effect on the movement of the float  100  based on the fluid only entering the top of the float, yet it allows fluid to drain slowly from float  100  if the float  100  is pulled out of the fluid. In an alternative embodiment, a separate cavity that does not drain through aperture  127  can be incorporated into float  100  such that when sensor assembly  16  is brought to the surface and tipped over, fluid can drain from the port  90  and holes  126 . One benefit of the alternative design is that the float  100  retains the mineralized water collected from the well. Dumping it out and visually seeing it verifies the test results for mineralized water. 
   While the basic components and structure of the interface tool  10  was described in greater detail above, it should be understood by one skilled in the art that several modifications could be made without departing from the sprit and scope of the invention. For example, instead of using a single multi-strand cable to power the sensor assembly, a more expensive two wire multi-strand cable could be used thereby eliminating the need for using the well casing to complete the alarm circuit. Using this approach, one wire would be connected to the electrical contact  96  and the other wire would be connected to the wire  112  connect at the bottom of the floating ground rod  98 . 
   The embodiments shown and described above are only exemplary. Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description together with details of the method of the invention, the disclosure is illustrative only and changes may be made within the principles of the invention to the full extent indicated by the broad general meaning of the terms used in the attached claims.