Abstract:
A towable separator unit for oil wells has a walled enclosure with tanks therein. The tanks, which are an oil-water tank, a water tank and an oil tank, are separated from one another by interior side walls. An inlet pipe brings well fluids to the oil-water tank via a flume that allows the contents to enter the tank and be separated. A water leg allows water on the bottom to pass into the water tank; the water leg in contained inside the enclosure so as not to be subject to freezing. An oil outlet pipe allows oil on top of the oil water tank to exit and flow by gravity into the oil tank. The tanks have liquid level sensors therein; the levels are displayed on the outside and are transmitted to a remote location. The water and oil tanks have outlets. The oil tank has plural outlets arranged vertically to allow determination of the water level therein.

Description:
SPECIFICATION 
       [0001]    This application claims the benefit of U.S. provisional application Ser. No. 61/954,154, filed Mar. 18, 2014. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a separator unit for separating oil and water produced from oil wells. 
       BACKGROUND OF THE INVENTION 
       [0003]    in addition to oil, oil wells typically produce unwanted fluids such as water. As fluid is produced to the surface by the well, it is desirable to separate water from the oil at the well site, before the oil is transported or sold. 
         [0004]    In the prior art, separator units and storage tanks are brought to the well site. This involves loading the separator unit onto a truck and trucking the unit to the well site. Likewise, storage tanks are loaded onto one or more additional trucks and the tanks are trucked to the well site. The separator unit and storage tanks are typically oversized. As a result, when trucked to the well site, special procedures are followed, such as using escorts warn motorists of the wide load. All of these trucks and special procedures add to the cost of transporting the equipment to and from the well site. 
         [0005]    Once delivered to the well site, the separator unit is located relative to the well and the storage tanks are located relative to the well and the separator unit. Lines running from the well to the separator unit are plumbed, as are lines from the separator unit to the storage tanks. The setup and installation of the equipment is time consuming and laborious. Once installed, the well is produced into the separator unit and the water is stored in a storage tank. The oil is stored in a separate storage tank. 
         [0006]    Thus, it is expensive to provide a well site with a separator and separate storage tanks for oil and water. Included in the cost is not lust the equipment, but the cost of installation and removal of the equipment. In some wells, the cost of such equipment may be too expensive relative to the production of the wells. For example, in small stripper wells, small quantities of oil are produced. Such wells may produce large amounts of water relative to oil and thus be in need of a separator and storage. Yet, the cost of installing and removing the equipment ma be prohibitively high. 
         [0007]    There is a need for a less expensive, less labor intensive, and more ecological reflective designed portable test separator unit. 
       SUMMARY OF THE INVENTION 
       [0008]    A towable separator unit for oil wells, comprises a chassis, wheels rotatable mounted to the chassis so the chassis can be towed and a walled enclosure supported by the chassis. The enclosure has top, bottom, exterior side and end walls, the walled enclosure having interior side walls arranged so as to form a first tank, a second tank and a third tank, each of the first, second, and third tanks capable of holding a fluid without leaking. An inlet pipe is structured and arranged to connect to an oil well, the inlet pipe communicating with the first tank so as to deliver fluids from the oil well into the first tank. A first transfer pipe has an inlet located in a bottom region of the first tank. The first transfer pipe having an outlet located in one of the second or third tanks, the first transfer pipe located interiorly of the walled enclosure. A second transfer pipe has an inlet located in a top region of the first tank, the second transfer pipe having an outlet located in the other of the second or third tanks, the second transfer pipe sloped downwardly from its inlet to its outlet. Each of the second and third tanks having an outlet. 
         [0009]    In accordance with one aspect, the first, second and third tanks are arranged longitudinally inside the walled enclosure, with the second tank between the first and third tanks. 
         [0010]    In accordance with another aspect, the top wall of the walled enclosure has a step down portion that is stepped down from the first tank to the third tank the second transfer pipe is located exterior to the stepped down portion of the top wall, further comprising a valve in the exterior portion of the second transfer pipe. 
         [0011]    In accordance with another aspect, the inlet pipe is connected to a flume located in the first tank, the flume extending vertically from the top wall toward the bottom wall, the flume having a lower portion with openings therein to allow the well fluid to enter the first tank, further comprising a perforated coalescer above the flume openings. 
         [0012]    In accordance with another aspect, the first transfer pipe comprises a water leg. 
         [0013]    In accordance with another aspect, the third tank has plural outlets arranged vertically along the third tank. 
         [0014]    In accordance with another aspect, further comprising a level sensor in at least one of the first, second or third tanks, the level sensor providing liquid level information to a display on the exterior of the walled enclosure. 
         [0015]    In accordance with another aspect, further comprising a wireless transmitter connected to the level sensor to provide level information remotely from the well. 
         [0016]    In accordance with another aspect, the level sensor measures the level of oil and also measures the level of water in the respective tank. 
         [0017]    In accordance with another aspect, wherein the inlet of the second transfer pipe comprises a stub removably connected to the second transfer pipe and having a length so as position the inlet of the second transfer pipe at a predetermined location above the bottom W all of the first tank. 
         [0018]    In accordance with another aspect, the unit is road legal. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  shows the separator unit at a well site, connected to a well. 
           [0020]      FIG. 2  is a side view of the separator unit, in accordance with a preferred embodiment. 
           [0021]      FIG. 3  is a top view of the separator unit. 
           [0022]      FIG. 4  is a rear end view of the separator unit. 
           [0023]      FIG. 5  is a front end view of the separator unit. 
           [0024]      FIG. 6  is a partial cross-sectional side view of the separator unit. 
           [0025]      FIG. 7  is a side elevational view of the flume. 
           [0026]      FIG. 8  is a side elevational view of the water leg. 
           [0027]      FIG. 9  is a detailed side elevational view of the inlet to the oil transfer pipe. 
           [0028]      FIG. 10  is a schematic view of a level sensor. 
           [0029]      FIG. 11  is a block diagram of the sensor system. 
           [0030]      FIG. 12  shows a liquid level sensor in accordance with another embodiment. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0031]      FIG. 1  shows an oil well site with an oil well  11 . The oil well is a stripper well that produces a small quantity of fluid on a daily basis. Much of the fluid produced is oil, but a quantity of water is also produced. In order to separate the oil, and the water and store both types of separated fluids, a separator unit  15  is used. 
         [0032]    The separator unit  15  is portable and fully self-contained. It is suitable for being towed on roads and simple to install and make ready for operation. Once in operation, the separator unit  15  is reliable with no active components such as pumps. Much of the plumbing is internal where it is protected from freezing and being damaged when the unit is towed on the road. Because little work needs to be done to set up and remove the separator unit  15  from a well site, the unit is safer to install and remove and is also safe to operate. 
         [0033]    When no longer needed, the separator unit  15  can easily be disconnected and towed off of the well site and reused at another well site. 
         [0034]    The separator unit  15  (see  FIG. 2 ) is a self-contained trailer, having a chassis frame  17 , wheels  19  and a towing hitch  21 . The trailer has a front end  23  near the hitch, and a rear end  25  near the wheels  19 . 
         [0035]    In addition, the separator unit has three tanks or compartments, namely an oil-water tank  27  (see  FIG. 6 ), a water tank  29  and an oil tank  31 . Each tank has a floor  33 , a top  35  and exterior side walls  37 . The exterior side walls  37  are corrugated. Each tank is provided with an access hatch  38  in the respective side wall. There are also interior side walls  39 ,  41  between the tanks. The oil-water tank  27  shares a side wall  39  with the water tank  29 . The water tank  29  shares a side wall  41  with the oil tank  31 . The interior surfaces of the tanks are epoxy coated. 
         [0036]    In the preferred embodiment, the oil-water tank  27  is located at the rear end  25 , the oil tank  31  at the front end  23  and the water tank  29  between the other two tanks. The oil-water tank and oil tank are about the same volume, while the water tank is smaller in volume, in the preferred embodiment. The relative sizes of the tanks can be changed to suit the particular needs of the well site. By way of example only, the oil-water tank can be  210  barrels, the oil tank  214  barrels and the water tank  150  barrels. 
         [0037]    The top  35  of the unit is stepped down from the rear end  25  to the front end  23 . The top of the oil water tank  27  is higher than the tops of the other two tanks  29 ,  31 . The top of the water tank  29  is stepped down  79  at a location between the interior side walls  39 ,  41  (see  FIG. 6 ). Steps  43  or a ladder can be provided at the front end  23  (see  FIGS. 2 and 5 ) to allow personnel to access the top  35 . The rear end  25  is equipped with lights  45  so that the trailer can legally travel on roads ( FIG. 4 ). 
         [0038]    An inlet pipe  47  is connected to the oil-water tank  27 . The inlet pipe  47  is connected to the well  11 , either directly, or indirectly by way of equipment such as a gas separator. The inlet pipe  47  extends along the exterior of the rear end  25  and along the top  35  of the oil-water tank  27  to a vertical pipe or flume  49 . Referring to  FIG. 7 , the flume  49  has an exterior or upper, portion  51  and an interior, or lower, portion  53 . The interior portion  53  is a pipe that extends from the top  35  to the floor  33  of the oil-water tank  27 . The top end of the pipe extends above the tank top  35  for a short distance. The pipe has cutouts or openings  54  in its tower end to allow the liquid in the pipe to escape into the tank  27 . A spreader  55 , or coalescer, is provided a distance above the floor  33 . The spreader is located above the openings  54 . The spreader  55  is attached to and extends out horizontally from the pipe. The spreader  55  is a perforated plate or mesh and could be made of expanded metal. The spreader can be a flat plate. If so, then the plate is provided with a downwardly depending skirt  56  that extends around the circumference of the plate. Alternatively, the plate can be domed, with the outer edges lower than the center. Thus, the oil and water is retained under the spreader for a period of time to allow the oil to coalesce. The lower portion of the flume  49  is located in the center of the lowest part of the tank  27 . 
         [0039]    The upper portion  51  stands up from the top  35  of the tank. The upper portion  51  is hinged  57  or otherwise movably coupled to the lower portion  53  top end. When the separator unit  15  is being transported, the upper portion  51  is laid down as shown b) dashed lines in  FIG. 7  in order to reduce the overall height of the unit. As an alternative, the upper portion  51  can be completely removed and stowed in a bracket on the side of the unti in order to lower the overall height of the unit. Handles can be provided on the upper portion to assist in moving the portion into place. On installation, the upper portion  51  is raised to a vertical position and is secured to the lower portion  53  with one or more clamps. A gasket between the upper and lower portions provides a seal. The connection is preferably a quick release clamp with a single bolt. This is in contrast to a typically pipe flanged connection with a number of bolts. The quick release clamp saves time in setup and take-down. The inlet pipe  47  is connected to the upper portion  51 . The inlet pipe  47  has a flexible portion  47 A that extends from the top wall to the flume top  51  to accommodate the flume top  51  moving about the hinge. 
         [0040]    Water is transferred from the oil-water tank  27  to the water tank  29  by way of a water leg  59  (see  FIG. 8 ). The water leg  59  has an upside down “U” shape and is located in the oil-water tank  27 . Thus, there are two vertical pipes  61  joined together by a horizontal pipe  63  which is located some distance above the floor  33 . One end of one of the vertical pipes  61  is open  65  to the oil-water tank  27  and is located close to the floor  33 . The other vertical pipe  61  joins to a horizontal pipe  67  which passes through the side wall  39  into the water tank  29  where it is open. A vertical riser  69  extends from one of the vertical pipes  61  above the top  35 . A weather cover can be provided over the open riser  69 . 
         [0041]    Oil is transferred from the oil-water tank  27  to the oil tank  31  by an oil transfer pipe  71 . The inlet  73  to the pipe  71  is located near the top  35  of the oil tank  27  (see  FIG. 9 ). The height of the inlet  73  above the floor  33  can be adjusted by adding or subtracting the lengths of vertical pipe stubs  75 . For example, adding a pipe stub  75  on top of the pipe creates an inlet  73 A that is higher relative to the floor  33 . The stubs  75  can be threaded into the pipe  71 . An access hatch  77  is provided on the top  35  in order to access the inlet  73  (see  FIG. 3 ). 
         [0042]    The oil transfer pipe  71  exits through the side wall  39 , extends along the upper portion of the water tank  29  for a distance and exits the water tank at the step down partition  79 . The pipe  71  continues along the top exterior toward the front end  33  where it enters the oil tank  31  at the top. The pipe is sloped down from the oil-water tank to the oil tank. A valve  81  is provided, which valve is accessed from the top  35  of the unit. 
         [0043]    An overflow and skim oil pipe  83  is provided between the water tank  29  and the oil tank  31 . The overflow pipe  83  (see  FIGS. 3 and 6 ) has an inlet near the top of the water tank  29  and extends out of the water tank at the step down  79 . The pipe  83  then enters the top of the oil tank  31 . The pipe  83  is provided a valve  85 , accessible from the top. Personnel can use the stairs  43  to climb on top and access the valves  81 ,  85  as well as access hatches. 
         [0044]    One or more tanks  27 ,  29 ,  31  are provided with level sensors  87  (see  FIG. 10 ). The sensors are conventional and commercially available. A tube  89  extends vertically inside the respective tank through the top down to the bottom or floor. A toroid float  91  can travel along the tube and tracks the liquid level  92 . As the float  91  moves, its position is detected by magnetic sensors inside the tube. In addition, the temperature of the fluid can be sensed by the unit. Electronic package  93  is located on top of the tube and sends the level and temperature information to a display  95  ( FIGS. 11 ), which is mounted at the front end  23  ( FIG. 5 ). 
         [0045]    Referring to  FIG. 11 , the level sensors  87  report to a monitor  97  which electronically monitors the levels. If a level in a tank exceeds a predetermined level, the monitor  97  initiates an alarm. The alarm is provided on the display and is also sent offsite by a wireless communications link, such as a satellite link (or cellular telephone link). A receiver  99  located offsite receives the alarm. The receiver can be a cellular telephone or smartphone. The system allows offsite personnel to monitor the status of the unit  15  to minimize overflow from the tanks. In addition to sending alarm information, the system can also send status updates on the liquid levels and temperatures. These can be sent on a periodic basis. The system can include a GPS (global positioning system) unit  100 . For example, the monitor and transmitter  97  can include a GPS unit  100 , wherein the location of the separator unit  15  is transmitted to the receiver  99 . The GPS unit  100  allows the separator unit  15  to be leased on a per location basis. If the unit is moved to another location outside of the terms of the lease (and without permission of the owner), the owner will know that the lease has been violated. 
         [0046]      FIG. 12  illustrates another embodiment of a liquid level sensor  109 . A vertical tube  111  is provided from the top wall  35  to the bottom  33 . The tube has a longitundinal slot therein to allow liquid in the tank to enter the tube at various levels. Alternatively, the tube can be provided with a series of slots or openings along the length of the tube to admit liquid therein. Inside the tube are two floats that move along the length of the tube interior. One float  113  is on top of the oil  115 , while the other float  117  is on top of the water  119 . Also inside of the tube  111  are magnetic sensors  121  that sense the positions of the two floats  113 ,  117 . The magnetic sensors are connected to the electronic package  93 . 
         [0047]    The sensor  109  is used in a tank having both oil and water. For example, one sensor  109  can be used in the oil-water tank  27  while another sensor  109  is used in the oil tank  31 . The water tank  29  can be provided with the sensor  109 , however typically the water tank contains little or no oil. 
         [0048]    As the levels of liquid  115 ,  119  vary, the respective floats  113 ,  117  move along inside the tube, with the oil float  113  following the oil level  115  and the water float  117  following the water level  119 . The positions of the floats are sensed by the sensors  121 , which are read by the electronics package  93  and sent to the display  95  and the receiver  99 . 
         [0049]    The water and oil tanks  29 ,  31  have takeoff valves in the respective side walls  37 . The water tank  29  takeoff valve  101  (see  FIG. 6 ) is located near the floor or bottom of the tank. The valve  101  allows a hose to be connected thereto so that water in the tank can be loaded into a truck for transport offsite. 
         [0050]    The oil tank  31  has a number of takeoff valves  103  (see  FIG. 5 ) vertically staggered and located at the front end  23 . Thus, the valves allow a user to sample the liquid inside at various vertical positions or vertical levels inside the tank. The oil inside the oil tank  31  is typically marketable. However, there may be some water located at the bottom. When an operator arrives to offload oil, the operator can open the various valves  103  to determine where the bottom level of the marketable oil is. For example, the operator can open the bottom valve. If water comes out or a combination of water and oil comes out, the operator knows that there is water at that particular level. The operator can open the next highest valve. If oil comes out of the valve, then the operator knows that oil is located at that level and above. Therefore, the operator would connect the hose to that valve, open a valve to offload the liquid oil for transport offsite. 
         [0051]    In operation, the unit  15  is towed to a well site. The unit is road legal, with lights and with a width and a height that allows it to be taken on public roads and beneath bridges and overpasses. An escort for the towed vehicle need not be provided as the unit  15  is towed on public roads. This saves labor and expense. At the well site, the unit is positioned as desired. The unit is then lowered to the ground; the chassis  17  bears on the ground. The well is connected to the inlet pipe  47 . The exterior portion  51  of the flume  49  is raised to a vertical position and clamped in place in addition, hand rails  105  can be installed on the landing, which hand rails have been taken off and stowed for transport As an alternative, the stairway landing can be lowered so as to lower the overall height of the hand rails  105 , which hand rails can then be permanently attached. Hand rails can be permanently attached along the steps up to the landing. The truck towing the trailer is disconnected and can be used for other jobs. Once connected, the unit is ready for operation and the well can be opened to produce into the unit. Oil and water flow through the inlet pipe  47  and descend into the oil-water tank  27  via the flume  49 . The liquid exits the flume through the openings  54  in the bottom. The water naturally stays at the bottom while the oil rises to the top. The spreader  55  slows the ascent of the oil and serves to coalesce small globules of oil into larger globules, which makes separation more effective. The flume  49  thus slows the velocity of the incoming liquid in order to assist in separation. 
         [0052]    The overall fluid level in the oil-water tank  27  rises as liquid continues to enter. When the level is high enough, water passes from the bottom of the oil-water tank  27 , through the water leg  59  and into the water tank  29 . Likewise, oil enters, the oil transfer pipe  71  near the top of the oil tank  27  and flows into the oil tank  31 . Thus, separation is accomplished automatically. 
         [0053]    Overflow protection and skim oil capability is provided. For example, in the preferred embodiment, the water tank  29  is smaller in volume than the oil tank  31 . If an operator, when onsite, and reading the display  95 , notices the water level in the water tank is high and close to overflowing, the operator can open the valve  85  and allow water to exit the water tank  29  via the overflow pipe  83  into the oil tank  31 . The operator is thus able to prevent a spill, which spill could have environmental consequences. Alternatively, if the water tank were larger than the oil tank, an overflow pipe could be provided, which allows flow from the oil tank into the water tank. 
         [0054]    Although liquid level sensors can be provided in one or more of the tanks  27 ,  29 ,  31 , sight glasses could be used as an alternative. Such sight glasses however are subject to breakage and, if filled with water, freezing. 
         [0055]    The overflow pipe  83  can be used to transfer skim oil out of the water tank  29 . The skim oil is at the top level of liquid in the water tank. An operator can open the valve  85  to transfer the skim oil out of the water tank  29  into the oil tank  31 . 
         [0056]    The separator unit is easy to install and set up, easy to remove from a well site and low in maintenance. It operates automatically, needing only occasional visits to offload the water and the oil, typically by truck. It is desired for cold climate use, as the water lines are all interior and not subject to freezing. 
         [0057]    The separator unit can be operated and liquid levels monitored by personnel on the ground. Personnel need not climb on top to gauge liquid levels, but can read the levels on the display  95 . The offload valves  101 ,  103  are provided at ground level. 
         [0058]    To remove the separator unit  15  from the well site, the well is disconnected by disconnecting the line  47 . Preferably, the tanks  27 ,  29 ,  31  are emptied into other vessels to reduce the weight of the unit  15 . All protruding objects such as the flume top and handrails are stowed. A towing vehicle is backed to the unit and connected to the trailer hitch  21 . As the unit front end is lifted onto the towing vehicle, the chassis  17  is lifted off the ground and the wheels  19  bear the weight. The unit  15  can now be towed on the wheels  19 . Thus, the unit is both set up and removed simply and quickly, saving on labor and materials. 
         [0059]    The unit  15  is road legal and is not an oversized load. As a result, one or more escorts for transporting the unit along a public road are not required. An example of a road legal load is a width not exceeding 102 inches and a height not exceeding 13 feet 6 inches. The unit  15  is within these dimensions. 
         [0060]    Although the unit  15  can be used as a self-contained separator, in some situations, the unit can be used in conjunction with other equipment. For example, the unit can be used with a separate water tank, if the well produces too much water for the water tank  29  and additional water storage is needed. As another example, the unit  15  can be used with a separate oil tank, to provide additional oil storage on the well site. 
         [0061]    The foregoing disclosure and showings made in the drawings are merely illustrative of the principles of this invention and are not to be interpreted in a limiting sense.