Abstract:
System and method directed to the art of heating a fluid for use in a hydraulic fracturing system. A heat tube having a plurality of pipes disposed axially along and substantially near the periphery of a medial portion of the heat tube. The heat tube is heated by induction heaters.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Hydraulic fracturing, commonly referred to as “fracing,” is a method of extracting hydrocarbons from a geological formation deep within the earth. The process entails a combination of drilling vertically and horizontally into the earth; introducing a mixture of water, a proppant (typically sand) to hold open the fractures, and optionally a chemical mixture to reduce equipment wear and to aid in the removal of the hydrocarbons; and building the pressure within the wellbore with the mixture until a sufficient pressure is achieved causing the formation to fracture, thus releasing the hydrocarbons which can be removed via the wellbore. 
         [0002]    Water is an important element in the fracing process as it carries the proppant and chemicals deep into the earth. Thus the properties of the water, specifically temperature, can make a difference in overall fracing performance and efficiency. Achieving a proper water temperature may reduce the amount of chemicals needed and also decrease the amount of pressure on the pumps, pipes, and joints. 
         [0003]    Heating the water generally involves pumping water into a heating vessel comprising a burner box, carrying the water through a coil (potentially 2″×1800′ in size) over an open flame, then introducing the heated water back into the fracing system. In order to heat this much water, upwards of 400 gallons per hour of propane or diesel fuel can be consumed. It also requires the added cost of fuel delivery and storage of flammable materials, and requires an open flame located near a mining system involving chemicals under pressure. Therefore, the art of fracing could benefit from a water heating system capable of more efficiently heating the water without use of an open flame. 
       SUMMARY OF THE INVENTION 
       [0004]    The present invention relates to a fluid heating device capable of heating water in a fracing process without the use of an open flame and in a way not requiring more efficient manner. 
         [0005]    One aspect of the present invention provides a fluid heating system having a heat tube comprising a plurality of pipes positioned axially along the heat tube and substantially near the periphery of the heat tube and at least one induction heater comprising at least one conductor, wherein the at least one conductor of the at least one induction heater is positioned around the periphery of the heat tube. 
         [0006]    The heat tube may also have an input portion, a medial portion comprising the plurality of pipes and having a medial portion first end and a medial portion second end, and an output portion, wherein the input portion adjoins the medial portion at the medial portion first end and the output portion adjoins the medial portion at the medial portion second end. 
         [0007]    The medial portion may have a medial portion diameter and the input portion may have an input portion first end diameter, wherein the medial portion diameter is larger than the input portion first end diameter. 
         [0008]    The input portion may be substantially frustoconical. 
         [0009]    The output portion may have an output portion second end diameter, wherein the medial portion diameter is larger than the output portion second end diameter. 
         [0010]    The output portion may be substantially frustoconical. 
         [0011]    Another aspect of the present invention provides a fluid heating system for use in hydraulic fracturing having a heat tube comprising a plurality of pipes positioned axially along the heat tube and substantially near the periphery of the heat tube and at least one induction heater comprising at least one conductor, wherein the at least one conductor of the at least one induction heater is positioned around the periphery of the heat tube. 
         [0012]    The heat tube may further comprise an input portion, a medial portion comprising the plurality of pipes and having a medial portion first end and a medial portion second end, and an output portion, wherein the input portion adjoins the medial portion at the medial portion first end and the output portion adjoins the medial portion at the medial portion second end. 
         [0013]    Another aspect of the present invention provides a method for heating a fluid for use in hydraulic fracturing comprising the steps of providing a fluid to be heated, providing a heat tube comprising a plurality of pipes disposed axially along and substantially near the periphery of the heat tube providing at least one induction heater, providing a power source, placing the at least one induction heater about the periphery of the medial portion, supplying electricity from the power source to the induction heater, and passing the fluid through the medial portion plurality of pipes. 
         [0014]    The heat tube may further comprise an input portion, a medial portion comprising a medial portion first end, a medial portion second end, and the plurality of pipes disposed axially along and substantially near the periphery of the medial portion, and an output portion, wherein the input portion is fluidly attached to the medial portion and the output portion is fluidly attached to the medial portion second end 
         [0015]    The method for heating a fluid for use in hydraulic fracturing may provide water as the fluid to be heated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  shows a prior art system for heating water for use in a hydraulic fracturing procedure. 
           [0017]      FIG. 2  illustrates a system for heating water in a hydraulic fracturing procedure according to the present invention. 
           [0018]      FIG. 3  is a perspective cut-away view of a heat tube according to the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0019]    Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structures. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims. 
         [0020]      FIG. 1  depicts a prior method and device  1000  for heating a fluid in a fracing system. Here a fluid, in this case water (not shown), is taken from a water source  70  and pumped by a pump  76  into a burner box  1000 . The burner box  1000  houses propane burners  1004  and a coil  1006 . The water flows through the coil  1006  and is heated by the propane burners  1004  with propane (not shown) supplied from a propane tank  1002 . The water then exits the burner box  1000  and continues downhole. As mentioned earlier, this system requires an open flame and a substantial amount of propane to heat the water flowing through the coil  1006  to a desired temperature. 
         [0021]    A fluid heating apparatus  10  according to the present invention is illustrated in  FIG. 2 . The fluid heating apparatus  10  replaces the burner box  1000  of the prior art method for heating a fluid in the fracing system described above. The fluid heating apparatus  10  comprises a heat tube  20 , a power source  78  (here a generator), and at least one induction heater  60 . It is contemplated that any combination of the pump  76 , the at least one induction heater  60 , the heat tube  20 , and the power source  78  may be provided on a single truck (not shown). 
         [0022]    The at least one induction heater  60  comprises at least one conductor  62 . Wherein the at least one conductor  62  is positioned around the heat tube  20 . The at least one induction heater  60  is powered by the power source  78 . Therefore, electricity produced by the power source  78  flows through the induction heater conductor  62  thereby producing heat which in turn transfers heat to the heat tube  20 . 
         [0023]    Looking now to  FIG. 3  in which the heat tube  20  is shown in greater detail. Here it can be seen that the heat tube  20  has a substantially circular cross-section and comprises an input portion  22  comprising an input portion first end  24  and an input portion second end  26 , a medial portion  30  comprising a medial portion first end  32  and a medial portion second end  34 , and an output portion  50  comprising an output portion first end  52  and an output portion second end  54 . Wherein the input portion second end  26  adjoins the medial portion first end  32  and the output portion first end  52  adjoins the medial portion second end  34 . 
         [0024]    The input portion first end  24  has an input portion first end diameter D 1  and the input portion second end  26  has an input portion second end diameter D 2 . The medial portion first end  32  and the medial portion second have a medial portion diameter D 2 . Furthermore, the output portion first end  52  has an output portion first end diameter D 4  and the output portion second end  54  has an output portion second end diameter D 5 . 
         [0025]    Moreover, the medial portion  30  comprises a plurality of individual pipes  40  disposed axially along and substantially near the periphery of the medial portion  30 . The pipes  40  extend through the medial portion first end  32  and the medial portion second end  34 . It is contemplated that the medial portion  30  comprises a surround  36  as shown in  FIG. 3 . The medial portion diameter D 3  is commensurate with the number of pipes  40  employed for a preferred flow rate, pressure, and heat transfer rate. 
         [0026]    Furthermore, the medial portion diameter D 3  is substantially constant throughout the medial portion  30  and the pipes  40  are preferably linear and of a predetermined pipe diameter D 6  appropriate for the preferred flow rate, pressure, and heat transfer rate. 
         [0027]    The input portion first end diameter D 1  is preferably substantially similar to the diameter of a pipe on the water-in side  72 . The input portion second end  26  is fluidly connected to the medial portion first end  32 . As the medial portion diameter D 3  may be larger than the pipe on the water-in side  72 , the input portion  22  may comprise an ever-increasing cross-sectional area from the input portion first end  24  to the input portion second end  26 . Furthermore, the transition from the input portion first end diameter D 1  to the input portion second end diameter D 2  may be designed to promote fluid travel and to reduce the likelihood of cavitation. As non-limiting examples, the input portion may be substantially frustoconical or similar to the neck and shoulder of an olpe-type vase. 
         [0028]    The output portion  50  is similar in design to the input portion  22 . The output portion first end diameter D 4  is substantially the same as the medial portion diameter D 3  and the output portion second end diameter D 5  is sized to be connected into a line on the water-out side  74 . As the medial portion diameter D 3  may be larger than the pipe on the water-out side  74 , the output portion  50  may comprise an ever-decreasing cross-sectional area from the output portion first end  52  to the output portion second end  54 . Furthermore, the transition from the output portion first end diameter D 4  to the output portion second end diameter D 5  may be designed to promote fluid travel and to reduce the likelihood of cavitation. As a non-limiting example, the output portion may be substantially frustoconical or similar to the neck and shoulder of an olpe-type vase. 
         [0029]    Furthermore, the input portion  22  and the output portion  50  may be joined to the medial portion  30  and also to the respective water-in side  72  and the water-out side  74  in any manner known in the art. Non-limiting examples include welding and flange connections. 
         [0030]    As stated earlier, the dimensions of the heat tube elements may be predetermined to provide various flow rates, pressures, and heat transfer rates. As a non-limiting example, the heat tube  20  may have an input portion first end diameter D 1  and an output portion second end diameter D 5  of approximately four inches, and the input portion second end diameter D 2 , the medial portion diameter D 3 , and the output portion first end diameter D 4  may be approximately ten inches. Additionally, each pipe  40  may have a diameter D 6  of 1″ and be comprised of schedule  40  metal pipe. 
         [0031]    Furthermore, referring to both  FIGS. 2 and 3 , the arrangement of the pipes  40  in the heat tube  20  guides the flow of the incoming water (not shown) from the water-in side  72  to substantially near the periphery of the heat tube  20 . The plurality of pipes  40  provide multiple individual paths for the water, thereby dividing the incoming water into smaller individual quantities and effectively increasing the surface area of the water passing through the medial portion  30 . As the water surface area is larger, it takes less energy to raise the temperature of the water in the medial portion  30  than if the water had not been divided. Additionally, because the at least one induction heater  60  is placed around the periphery of the heat tube, and the pipes  40  are placed substantially near and around the periphery of the heat tube  20 , the applied heat is more evenly distributed to the water flowing through the pipes than would be if heated only from one direction. 
         [0032]    It is contemplated that the water entering the fluid heating apparatus  10  may be first pressurized by the pump  76 . It is further contemplated that the water entering the fluid heating apparatus  10  may be a diverted portion of the water supplied from the water source  70 . 
         [0033]    Additionally contemplated by the present invention is a method for more effectively heating a fluid in a fracing system. The method comprises providing a fluid to be heated; providing a heat tube comprising an input portion, a medial portion comprising a medial portion first end, a medial portion second end, and a plurality of pipes disposed axially along and substantially near the periphery of the medial portion, and an output portion, wherein the input portion is fluidly attached to the medial portion and the output portion is fluidly attached to the medial portion second end; providing at least one induction heater; providing a power source; placing the induction heater about the periphery of the medial portion; supplying electricity from the power source to the induction heater; and passing the fluid through the medial portion plurality of pipes. 
         [0034]    The foregoing is considered as illustrative only of the principles of the invention. Furthermore, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described. While the preferred embodiment has been described, the details may be changed without departing from the invention, which is defined by the claims.