Abstract:
A method of hydraulic fracturing of an oil producing formation includes the provision of a heating apparatus which is transportable and that has a vessel for containing water. The method contemplates heating the water up to a temperature of about 200° F. (93.3° C.). A water stream of cool or cold water is transmitted from a source to a mixer, the cool water stream being at ambient temperature. The mixer has an inlet that receives cool or cold water from the source and an outlet that enables a discharge of a mix of cool or cold water and the hot water. After mixing in the mixer, the water assumes a temperature that is suitable for mixing with chemicals that are used in the fracturing process, such as a temperature of about 40°-120° F.+ (4.4-48.9° C.+). An outlet discharges a mix of the cool and hot water to surge tanks or to mixing tanks. In the mixing tanks, a proppant and an optional selected chemical or chemicals are added to the water which has been warmed. From the mixing tanks, the water with proppant and optional chemicals is injected into the well for part of the hydraulic fracturing operation. The mixer preferably employs lateral fittings that enable heated water to enter the mixer bore at an acute angle. The mixer can also provide a lateral fitting that exits the mixer bore upstream of the first lateral fitting, the second lateral fitting transmitting water via a conduit such as a hose to the heater.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a continuation of U.S. patent application Ser. No. 12/842,738, filed 23 Jul. 2010. 
         [0002]    Incorporated herein by reference are my prior U.S. patent application Ser. No. 12/842,738, filed 23 Jul. 2010, my prior U.S. provisional patent application No. 61/297,097, filed 21 Jan. 2010, my prior U.S. provisional patent application No. 61/254,122, filed 22 Oct. 2009, and my prior U.S. provisional patent application No. 61/276,950, filed 18 Sep. 2009. Priority of these applications is hereby claimed. 
         [0003]    Also incorporated herein by reference is International Application Serial No. PCT/US2010/045791, filed 17 Aug. 2010 (published 24 Mar. 2011 as International Patent Publication No. WO 2011/034679 A2). 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0004]    Not applicable 
       REFERENCE TO A “MICROFICHE APPENDIX” 
       [0005]    Not applicable 
       BACKGROUND OF THE INVENTION 
       [0006]    1. Field of the Invention 
         [0007]    The present invention relates to a method and apparatus for the continuous preparation of heated water flow for use in hydraulic fracturing. 
         [0008]    2. General Background of the Invention 
         [0009]    In connection with production of oil or gas from a geological formation, the production may have a poor flow rate due to low permeability or from damage or clogging of the formation during drilling particularly in formations of tight sands with low porosity and oil &amp; gas shales. Hydraulic fracturing also known as “fracing” is a process employed after the well has been drilled, for the completion of the well to enhance hydrocarbon production. 
         [0010]    Hydraulic fracturing creates porosity by fracturing the formations surrounding the wellbore. These fractures allow the oil or gas to flow more easily from the tight sands or shales to the production well. The common method to create fractures in the formation is to pump a mixture of water, chemicals and sands into the rock or formation. When the pumped fluid mixture reaches sufficient pressures, the formation will fracture, creating the permeability required to release the captured hydrocarbons. 
         [0011]    Hydraulic fracturing generally entails injecting fluid into the wellbore at a sufficient rate and pressure to overcome the tensile strength of the formation creating cracks or fractures extending from the wellbore. U.S. Pat. No. 3,816,151, U.S. Pat. No. 3,938,594 and U.S. Pat. No. 4,137,182 (each hereby incorporated herein by reference) relate to hydraulic fracturing processes using various fracturing fluids. 
         [0012]    Also incorporated herein by reference are the following US Patent document nos: 2008/0029267; U.S. Pat. Nos. 5,979,549; 5,586,720; 5,183,029; 5,038,853; 4,518,568; 4,076,628; 2,631,017; 2,486,141; 2,395,258; 2,122,900; 2,065,789. 
         [0013]    One of the key elements of the fracturing fluid is water, which is the carrying fluid for the proppant (and optional appropriate chemical mix) required for the process. The proppant holds open the fractures and provides porosity to allow hydrocarbons to flow out of the formation. Before the fracing fluid is injected into the well, the water is normally heated to the target temperature (e.g., 40° F. to 120° F.+ (4.4° C. to 48.9° C.+)), which depends on the geologic formation and chemicals used, for example, typically 65° F.-75° F. (18° C.-24° C.) in the Bakken Shale located in North Dakota, Montana, and southern Canada) in order to achieve the proper chemical mix required for each particular hydraulic fracturing operation. A further result of heating the water prior to mixing with chemicals is the reduction of amount of chemicals that may be required for the hydraulic fracturing operation. In addition, a lower density of the heated water reduces the pressure on the pipes and connections and thereby reduces the risk for mechanical failure. In colder months and in colder environments, the temperature of the available water sources are typically less than 50° F. (10° C.) (even as low as below freezing) which is generally an unsuitably cold temperature for the fracing process. It is necessary to heat the available water to a temperature (e.g., 40° F. to 120° F.+ (4.4° C. to 48.9° C.+)) suitable for the fracing process prior to the water and fracing fluids being pumped down hole. 
         [0014]    There are common and known methods of providing heated water, which require that prior to the fracing process, the source water is pumped into numerous frac tanks and then the water in each individual frac tank is circulated through a heating unit to raise the temperature in the frac tank to a preset temperature required for the chemical mixing of the frac. However, due to the time lapse between heating (which is typically done the night before the fracing operations) significant thermal loss occurs. Each tank has to be heated to temperatures of for example 10-50° F. (5.6° C. to 27.8° C.) (often 20° F. to 30° F. (−11.1° C. to 16.7° C.)) higher than is operationally necessary. For example, if the required temp is 70° F. (21° C.), then each tank would need to be heated to at least 90°-120° F. (32° C.-48.9° C.). The extensive over-heating is a substantial expense and energy waste. The pumping of water to the frac tanks and the use of heating units to heat the water in the frac tank are well known in the industry.  FIG. 5  is an example of a prior art type configuration. There are multiple commercial businesses which provide such services. The number of frac tanks can typically range from 20-700 tanks (the average at the Marcellus Shale (located in western New York extending south to Tennessee) is 500 tanks)—currently it costs around $500-2,000 per frac tank in a typical fracing process (delivery, rental, cleaning, and demobilization of the tank), so these frac tanks are a substantial expense in the fracing process. Typically a substantial amount of safety issues in fracing operations involves the handling of frac tanks. One must heat the frac tanks to enough above the target temperature to allow for thermal loss between heating and use. Because normally heating of frac tanks occurs at night, this can be 10-50 degrees F. (5.6° C. to 27.8° C.), for example. The amount of temperature above target will depend on local weather conditions. 
       BRIEF SUMMARY OF THE INVENTION 
       [0015]    The apparatus and method of the invention requires a water source, pumps and piping that can provide continuous delivery of water, such as up to about 100 barrels (11.9 kl) (sometimes as high as 150 (17.9 kl), and sometimes as low as 30-50 barrels (3.6-6.0 kl)) a minute through a mixer or mixing manifold and to frac tanks. 
         [0016]    As the water (usually cool or cold water) is pumped from its source through the mixing manifold, a portion of the water volume (for example 7 barrels (0.83 kl) a minute) is diverted through piping at the manifold to and through a heating unit. This heating device is preferably a mobile unit that can heat a smaller volume of water, such as up to about 7 barrels (0.83 kl) per minute with a for example 22 million BTU (23.2 billion Joules) heater (which consistently heats to that capacity in all weather conditions, regardless of ambient temperatures). 
         [0017]    The heating unit creates an increase in the ambient water temperature of the e.g., 7 bbls (0.83 kl) of the diverted water to usually around 190-200° F. (87.8-93.3° C.) (and up to 240° F. (116° C.) in a pressurized piping system). This heating is preferably done on a continuous flow basis (as opposed to a batch process) with the heated water delivered through piping back into the mixing manifold and continuously mixed into the ambient water flow. The mixing of the superheated water with the cooler water results in an increase in water temperature of approximately 5°-15° F. (2.8-8.3° C.) at a rate of e.g. 100 barrels (bbls) (11.9 kl) per minute of continuous pumping flow (per each heater unit). Lower flow rates (such as 20 bbls (2.4 kl) per minute) will increase the temperature faster to result in a higher temperature rise. One can even run at 150 bbls (17.9 kl) per minute, but the temperature rise per unit will be lower. 
         [0018]    To achieve higher water temperatures, multiple heating units (for example 2-4 or even more) can be used to heat the water, all of which is preferably done on a continuous flow basis. The moving stream of uniformly heated water is preferably piped to a small number of optional frac tank(s) which can be used as a safety buffer between the water flow and the pumping operations, in the case of a mechanical breakdown or operational problems. 
         [0019]    The heating system with manifold can be designed for continuous heating preferably up to about 100 bbls (11.9 kl) per minute (or even more). To meet the required (target) temperature for the water used in the fracing process (e.g., 40° F. to 120° F.+ (4.4° C. to 48.9° C.+), and often about 65°-75° F. (18° C.-24° C.), or 70°-80° F. (21° C.-27° C.)), the rate of flow from the ambient source water can be adjusted to provide greater or lesser volume and multiple, sequential mixing manifolds and heater units can be added to the process. 
         [0020]    The mixing manifold includes an intake opening and an outflow opening allowing the source flowing water to pass through the mixing manifold to the frac tanks. Between the intake opening and the outflow opening, the mixing manifold has at least one cold water diversion opening connected to piping to deliver a portion of cold water flow to the heating unit. In the mixing manifold, a hot water return opening is located downstream of the cold water diversion opening, and this second opening, referred to as the hot water return opening, allows the heated water into the mixing manifold mixing with the cold water stream uniformly raising the temperature of the water before the water reaches the frac tanks (or the mixing tank or tanks if frac tanks are omitted). 
         [0021]    In another embodiment, before pumping the heated water to a frac tank (or the mixing tank or tanks if frac tanks are omitted), the flow of the mixed heated water can again be passed through a second mixer or second mixing manifold and a portion of the mixed heated water is diverted to a second heating unit to heat that water to 200° F. to 240° F. (93.3° C. to 116° C.), and that superheated water can be returned to the mixing manifold for mixing with the continuously moving water stream at about 100 bbls. (11.9 kl) per minute providing an additional +10° F. to +15° F. (+5.6° C. to +8.4° C.) uniform elevation of the temperature of the water flow. This mixed and heated water can then be piped to optional frac tanks (if used) and then to a mixing tank(s) for mixing with fracing chemicals and then pumped down hole for use in the hydraulic fracing process. If needed, multiple sequential heating units can be attached along the pumping line to continuously raise the temperature of the continuous flow of water to the required or predetermined target temperature. 
         [0022]    The mixing manifold can be any length or size of pipe or tank used in the industry and the cold water diversion opening and the hot water return opening can be configured and spaced in the mixing manifold, or along the piping, in any useful manner to allow superheated water to mix with continuously flowing source water. 
         [0023]    The mixing manifold or mixer can be for example 6-12 inches (15-30 cm) in diameter, such as a 10 inch (25 cm) diameter tubular member or pipe with a length of approximately 2 to 3 feet (61-91 cm). The pipe diameter and length can vary according to the requirements of the pumping operations. The cold water diversion opening is connected to a smaller pipe (such as a 3 inch (7.6 cm) pipe) that is preferably attached to the mixing manifold at an angle (such as approximately 45°) forming a “y” with the mixing manifold and the cold water diversion pipe. When heating water in Oklahoma, some operators use 10-inch (25 cm) lines, some use 12-inch (30 cm) lines. When heating water in Pennsylvania, some operators use 10-inch (25 cm) lines, and others use four to six 6-inch (10-15 cm) lines. 
         [0024]    Preferably, a raised rigid semi-circle shaped lip extends from the backside of the cold water diversion opening into the mixing manifold creating a partial blockage or impediment of the source water flow stream causing a portion of the cold water flow stream to divert into the cold water diversion opening and through the piping to the heating unit. This protruding lip partially blocks and obstructs the water flow inducing suction and flow into the pipe to the heating unit. This partial blockage in the mixing manifold also creates turbulence in the source water flow at and beyond the cold water diversion opening that aids in mixing at the superheated water inflow point. The lip can be a rigid metal concave half circle having for example a ⅛ inch (0.32 cm) width and 1.5 inch to 2 inch (3.81 cm to 5.08 cm) height at its highest point with tapering to meet flush with the side of the mixing manifold at the ends of the semi-circle of the lip; however, the lip can be many shapes, sizes and locations in the mixing manifold to induce suction and create turbulence in the mixing manifold. 
         [0025]    The hot water return opening in the manifold for attachment of piping for the superheated water is preferably located downstream of the cold water diversion opening in the flowing source water in the mixing manifold of the outflow pipe. The hot water return opening for delivery of superheated water preferably likewise has a lip extending into the stream of flowing water creating further turbulence in the water resulting in greater mixing action of the superheated water with the continuously flowing cold water creating a rise in temperature of the cold water as it passes along the mixing manifold and through the piping to the frac tanks serving as surge tanks (or directly to mixing tanks if there are no frac tanks acting as surge tanks). This second lip located on the front side or upstream side of the opening provides a partial blocking of the flow of cold water aiding in the flow of the superheated water into the mixing manifold. This lip adjacent to the opening on the hot water return opening is optimally of the same size and shape of the cold water diversion lip; however, this lip can also be utilized in many shapes, sizes and locations in the mixing manifold to partially block flow to facilitate hot water flow into the mixing manifold and create additional turbulence in the mixing manifold. 
         [0026]    Additional mixing of the hot and cold water occurs beyond the mixing manifold as the water flow is piped into and fills the optional frac tanks if used and then piped as operations dictate to mixing tanks to frac pumping units and to downhole. The heated water is delivered and can be temporarily held in frac tanks or surge tanks or pumped directly to mixing tanks without surge tanks. The apparatus and process substantially reduce the number of required frac tanks (or even eliminate the need for frac tanks). In one embodiment of the described process, approximately six to eight 500 bbl (59.6 kl) frac tanks are utilized, which are used as a safety buffer between the water flow and the pumping operations, in the case of a mechanical breakdown or operational problems. 
         [0027]    Suitable heating units can be commercially purchased through manufacturers or fabricated. Exemplary manufacturers include Rush Sales Company located in Odessa, Tex. (they produce Rush Frac Water Heaters), and Chandler Manufacturing, Inc. in Wichita Falls, Tex. (the diesel unit with six burners and a 22 million BTU (23.2 billion Joules) capacity is preferred) and Vita International. Conventional heating trucks shown in  FIG. 5  typically produce much less than 20 million BTU (21.1 billion Joules). They could be used in the system and method of the present invention, but more robust heating units 12 (such as those produced by Chandler Manufacturing, Inc.) capable of delivery of at least 15 million BTU (15.8 billion Joules), preferably up to 25 million BTU (26.4 billion Joules) (e.g. 22 million BTU (23.2 billion Joules) or more) are preferred. The piping, pumps and frac tanks are all readily available from numerous suppliers and contractors in the industry. 
         [0028]    There are numerous other conceivable arrangements and configurations of the inflow and outflow of the cold water and hot water and piping in the mixing manifold, including parallel pumping of cold and hot water inflow and use of secondary source of water to the heaters independent of the primary source water passing through the mixing manifold. 
         [0029]    The method of this invention can include some or all of the following steps. These steps can be in the following order. 
         [0030]    1) Establish a flow of source water at between about 20-150+ bbls (2.4-17.9+ kl) (more typically 60 to 100 bbls (7.2 to 11.9 kl)) per minute through piping to a piping manifold or mixer, which diverts a portion of the source water to one or more heating units, 
         [0031]    2) The superheated water returns to the continuous flowing source water to meet the required or target temperatures, and 
         [0032]    3) The warmed water (e.g. 60°-120° F.+ (16-48.9° C.+), typically 65°-80° F. (18-27° C.)) sent to the mixing tanks for chemical additives and the eventual fracing process. 
         [0033]    Examples of chemicals that can be added to the water include: bentonite gel and other chemicals used by such frac operators as Schlumberger, Halliburton, and BJ Services. Typically proppants (such as sand, ceramic beads, bauxite, or others) are mixed with the water before the water is injected downhole. The proppants help to keep the fractures which are produced open. The proppants can be for example any which are used by such frac operators as Schlumberger, Halliburton, and BJ Services. 
         [0034]    In general, it is possible to use water of a lower temperature if one uses more chemicals. For example, while normally one might wish to use water of 40°-120° F. (4.4° C.-48.9° C.) in a particular fracing process at a particular location (“slick water frac” refers to a process where less chemicals are used (or sometimes even no chemicals)—it uses turbulent flow with a lot of pressure—proppants are used with all fracing processes—typically one can carry more (sometimes up to two to three times as much) proppant in a slick water frac compared to a gel frac), one could instead use water at a lower temperature of 60°-120° F. (16° C.-48.9° C.) (“gel frac” refers to this process where more chemicals are used—gel and proppant). Examples of amounts of water used in a fracing process are 30,000 barrels to 350,000 barrels (3,577-41,734 kl), though one might use as few as 10,000 barrels (1,192 kl) to over one million barrels (119,240 kl) (this larger amount may cover multiple wells, for example). Higher water temperature can sometimes result in lower chemical usage. Some of the wells currently are approaching 1 million pounds (453,592 kg) of sand as a proppant with 350,000 barrels (41,734 kl) of water. 
         [0035]    Through testing in cold temperatures, the inventor has learned that heating water from around freezing to about 40 degrees F. (4.4° C.) takes a great degree of heat. One might need more heaters when heating water from near freezing, or one might initially preheat some water in frac tanks (e.g., 3 or 4 up to 50 or 100 frac tanks) to add heat one needs to move the temperature of the water up from near freezing to about 40 degrees F. (4.4° C.). One could also add heating in a water pit itself to help raise the water temperature to around 40 degrees F. (4.4° C.). Also, when a water source contains ice, it is best to withdraw only liquid water, and no ice, from the water source. Otherwise, a good amount of heat can be lost melting the ice. 
         [0036]    Preferably one places one or two units near the water source and another unit near the fracing pumps. It appears that there is additional heating in the pipeline (due to friction, the inventor believes) of perhaps a degree or two F. (0.6-1.1° C.) when the water travels about a mile (1.61 km). 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0037]    For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein: 
           [0038]    The invention and features of the invention is shown and disclosed by the following Figures and photographs representing informal drawings. 
           [0039]      FIG. 1  is a partial perspective view of a preferred embodiment of the apparatus of the present invention; 
           [0040]      FIG. 2  is a sectional view taken along lines  2 - 2  of  FIG. 1 ; 
           [0041]      FIG. 3  is a schematic diagram of a preferred embodiment of the apparatus of the present invention and illustrating the method of the present invention; 
           [0042]      FIG. 4  is a schematic diagram of another preferred embodiment of the apparatus of the present invention and illustrating a method of the present invention; 
           [0043]      FIG. 5  is a schematic diagram of a prior art oil well frac pumping system; 
           [0044]      FIG. 6  is a schematic diagram of a preferred embodiment of the apparatus of the present invention; 
           [0045]      FIG. 7  is a schematic diagram of an alternative embodiment of the apparatus of the present invention; 
           [0046]      FIG. 8  is a schematic diagram of another alternative embodiment of the apparatus of the present invention; 
           [0047]      FIG. 9  is a schematic diagram of another alternative embodiment of the apparatus of the present invention; 
           [0048]      FIG. 10  is a schematic diagram of another alternative embodiment of the apparatus of the present invention; 
           [0049]      FIG. 11  is a schematic diagram of another alternative embodiment of the apparatus of the present invention; and 
           [0050]      FIG. 12  is a schematic diagram of another alternative embodiment of the apparatus of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0051]      FIGS. 1-4  and  6 - 12  show preferred embodiments of the apparatus of the present invention, designated generally by the numeral  10  in  FIGS. 3 and 6 . Alternate embodiments are designated by the numeral  110  in  FIG. 4 , by the numeral  210  in  FIG. 7 , by the numeral  310  in  FIG. 8 , by the numeral  410  in  FIG. 9 , by the numeral  510  in  FIG. 10 , by the numeral  610  in  FIG. 11 , and by the numeral  710  in  FIG. 12 . In  FIG. 6 , a water source  11  can be a reservoir, lake or other source of water. 
         [0052]    Mobile heater apparatus  12  is used to super heat water for use in frac operations in an oil well. In general, such frac operations can be seen in U.S. Pat. No. 4,137,182, hereby incorporated herein by reference. 
         [0053]    Mobile heater  12  is a transportable heating apparatus and includes a truck  13  and a trailer  14 . Trailer  14  carries a heating vessel  15  which can be, for example, a tank or piping that holds water and that can be heated with electrical or other heating elements or with propane or preferably diesel burners. Water to be injected into an oil well  16  as part of a hydraulic fracturing operation include very hot water that is heated by mobile heater  12  and ambient water that is received from water source  11 . 
         [0054]    A pumping apparatus  17  which can include a truck  13  and trailer  18  pumps the prepared water (water plus selected chemical (optional) and proppant) into the well  16 . Water from source  11  flows in flowline  19  to mixer  20 . Mixer or mixing manifold  20  can be seen in more detail in  FIGS. 1 and 2 . Mixer  20  receives ambient temperature water from water source  11  and mixes that ambient temperature water with very hot water that is heated in vessel  15  of mobile heater  12 . 
         [0055]    The details of mixer  20  are seen in  FIGS. 1 and 2 . The mixer  20  has a tubular or cylindrically-shaped body  21  defined by a wall  22  which surrounds bore  23 . Tubular body  21  has a first inlet  26  in a first inlet end portion  24 , and a first outlet  27  in an outlet end portion  25 . The bore  23  communicates with flow inlet  26  and flow outlet  27 . Arrows  28 ,  29  illustrate the direction of flow of water in body  21  as shown in  FIG. 2 . Curved arrows  30  in  FIG. 2  illustrate turbulent flow that occurs for ensuring that heated water and ambient temperature water thoroughly mix. 
         [0056]    A pair of conduits are connected to tubular body  21 . These include conduit  31  and conduit  32 . Conduit  31  is a second outlet and removes ambient temperature water from the bore  23  of tubular body  21 . Conduit  32  is a second inlet and injects heated water into bore  23  of tubular body  21  and downstream of conduit  31 . In this fashion, conduit  31  does not discharge any heated water from bore  23  of tubular body  21 . Rather, the water leaving bore  23  of tubular body  21  via conduit  31  is ambient temperature water. This discharge of ambient temperature from tubular body  21  of mixer  20  is illustrated by arrows  39  in  FIG. 2 . 
         [0057]    Each of the conduits  31 ,  32  has a bore. The conduit  31  has bore  33 . The conduit  32  has bore  34 . Each of the conduits  31 ,  32  has an inner end portion and an outer end portion. Conduit  31  has inner end portion  35  and outer end portion  36 . Conduit  32  has inner end portion  37  and outer end portion  38 . Each of the inner end portions  35 ,  37  occupies a position within bore  23  of tubular body  21  as shown in  FIG. 2 . In this fashion, bore  33  of conduit  31  occupies a part of bore  23  of tubular body  21 . Similarly, fluid discharging from bore  34  of conduit  32  is discharged directly into the bore  23  of tubular body  21 . The arrows  40  in  FIG. 2  illustrate the discharge of heated water via conduit  32  into bore  23  of tubular body  21 . 
         [0058]    While the angle of the longitudinal axis of bore  33  of conduit  31  and the angle of the longitudinal axis of bore  34  of conduit  32  in relation to the longitudinal axis of bore  23  of tubular body  21  are shown to be about 45 degrees, those angles could vary from 0 to 90 degrees, and they need not be the same. 
         [0059]    As can be seen in  FIG. 2 , first inlet  26  is upstream of second outlet  31 , which is upstream of second inlet  32 , which itself is upstream of first outlet  27 . 
         [0060]    In  FIG. 6 , flow lines  41  and  42  are used to transfer water in between mobile heater  12  and mixer  20 . The flow line  41  receives water from conduit  31 , a second outlet, which is ambient temperature water and transports that ambient temperature water to vessel  15  of heater  12 . After water has been heated in vessel  15 , it is transported via flow line  42  to conduit  32 , a second inlet, of mixer  20 . It should be understood that the flow of fluids from flow line  41  to and through vessel  15  of heater  12  and then to flow line  42  can be a continuous process. As an example, the flow of ambient temperature water in flow line  19  can be about 20-150 bbls (2.4-17.9 kl) per minute, and typically around 60-100 barrels (7.2-11.9 kl) per minute. The flow rate in flow lines  41  and  42  can be for example a continuous 7 barrels (0.83 kl) per minute. 
         [0061]    The temperature in the super heated flow line  42  can be in excess of 200° F. (93.3° C.) and in excess of 240° F. (116° C.) if flow line  42  is pressurized. Flow lines  43  and  44  illustrate the transfer of warmed water from mixing tanks or downhole tanks  46  to pumping apparatus  17  and then into the well  16  for use in frac operations. In  FIG. 6 , surge tanks  45  can optionally be used downstream of mixer  20  and upstream of mixing tanks  46 . 
         [0062]    To achieve higher water temperatures, multiple heating units  12  can be used to heat the water all of which is done on a continuous flow basis as shown in  FIG. 4 . The moving stream of uniformly heated water can be piped to surge tank(s) which can be used as a safety buffer between the water flow and the pumping operations, in the case of a mechanical breakdown or operational problems. 
         [0063]    In  FIG. 4 , a joint of pipe  47  (commercially available) can be placed in between the two mixers  20  as shown. In  FIG. 4 , the flow of the mixed heated water can be passed through a second mixer or second mixing manifold  20  and a portion of the mixed heated water is diverted to a second heating unit  12  to heat that water to for example between about 200° F. to 240° F. (93.3° C. to 116° C.). That superheated water can be returned to the mixing manifold  20  for mixing with the continuously moving water stream providing an additional +10° F. to +15° F. (+5.6° C. to +8.4° C.) uniform elevation of the temperature of the water flow. This mixed and heated water can then be piped to mixing tanks  46  for mixing with any selected hydraulic fracturing chemicals and then pumped down hole for use in the hydraulic fracturing process. If needed, multiple sequential heating units  12  (and mixers  20 ) can be attached along the pumping line to continuously raise the temperature of the continuous flow of water to a required or target temperature. The mixers  20  can be connected in series (as in  FIG. 4 ) or in parallel or a combination of series and parallel (as in  FIGS. 10 and 12 ). 
         [0064]    In  FIG. 7  (an alternate configuration), the surge tanks have been eliminated. The mixing tanks  46  can be used to mix any selected chemical and proppant or proppants with the water that has been discharged from mixer  20  and that is ready for use in hydraulic fracturing operation in the well  16 . 
         [0065]    Conventional heater trucks  112  shown in  FIG. 5  typically produce much less than 20 million BTU (21.1 billion Joules). They could be used in the system and method of the present invention, but more robust heating units  12  (such as those produced by Chandler Manufacturing, Inc. in Wichita Falls, Tex.) capable of delivery of 22 million BTU (23.2 billion Joules) or more are preferred. Especially preferred are diesel powered heater units commercially available from Chandler Manufacturing, Inc. in which water flows through a series of metal coils, and there are six burners which heat the coils. An example of such a heater unit can be seen at www.chandlermfg.com/item.php?pid=34 and is identified as an oil-fired frac water heater (and shown in US Patent Publication no. US 2010/0000508). However, other heater units which can quickly heat large quantities of water can be used. The diesel powered units are preferred because in colder environments propane tends to liquify and not heat as effectively. Preferably one can run 70-100 barrels (8.3-11.9 kl) per minute per heating truck of the present invention while getting a temperature rise of at least about 15 degrees Fahrenheit (8.4° C.). 
         [0066]    Through testing in cold temperatures, the inventor has learned that heating water from around freezing to about 40 degrees F. (4.4° C.) takes a great degree of heat. One might need more heaters  12  when heating water from near freezing, or one might initially preheat some water in additional frac tanks (e.g., 3 or 4 up to 50 or 100 frac tanks) to add heat one needs to move the temperature of the water up from near freezing to about 40 degrees F. (4.4° C.). One could also add heating in a water pit itself (e.g., when the water source  11  is a pond) to help raise the water temperature to around 40 or 45 degrees F. (4.4 or 7.2° C.) (there will be radiant heat loss from the water pit, so typically one would not want to heat the water in the pit much above 40 to 45 degrees F. (4.4 to 7.2° C.)) before further heating the water with the heating system of present invention shown in  FIGS. 3 and 4 , for example. The heating in the water pit could be done with, for example, a heater or heaters  12  as shown in  FIGS. 3 and 4  that circulate water through hoses  41  and  42  to and from the water pit. 
         [0067]    Also, while typically water freezes at 32 degrees F. (0° C.), flowing water or water with various substances can sometimes cool below 32 degrees F. (0° C.) without freezing. Thus, sometimes the present invention might start processing water which is below 32 degrees F. (0° C.). Also, sometimes the source water might have ice in it, but it can still be used if the water with ice can flow through mixer  20 . However, it is preferred to avoid pulling ice into the intake, as considerable heat can be lost when melting the ice. 
         [0068]    Surge or pivot tanks  45  are preferably upright circular tanks where the water flows in and out (similar to or the same as the mixing tanks  46  shown in  FIG. 6 ). The agitation which occurs in the surge tanks  45  is helpful, and seem to add heat to the water (better mixing seems to occur as well, so even if surge or pivot tanks  45  are not needed for surge, one might want to use 2-20 of these anyway). 
         [0069]    Manifolding among multiple surge or pivot tanks can be done to balance heat. Pivot or surge tanks  45  could be shaped like mixing tanks  46 . Preferably the heated water flows through the surge tanks (as shown in  FIG. 10 , where mixing tanks  46  are acting as surge tanks). The surge tanks provide a buffer in the event of some breakdown or other problem making it difficult to produce heater water. During the breakdown or other problem, heated water from the surge tanks can be routed to the mixing tanks, even though no heated water will be refilling the surge tanks. Preferably, either enough surge tanks are provided that no interruption in fracing occurs during a breakdown or other problem causing an interruption in heated water production, or enough surge tanks are provided that an orderly shutdown of fracing occurs during a breakdown or other problem causing an interruption in heated water production. Typically surge tanks hold around 480-500 barrels (57.2-59.6 kl) of heated water per tank. 
         [0070]    Though pumps and valves are not shown in the drawings, appropriate pumps and valves are provided to direct water as desired, and one of ordinary skill in the art will be able to determine where to place such pumps and valves to achieve desired water flow. 
         [0071]    Water lines can be manifolded together and several lines could feed and emanate from a single heating truck. 
         [0072]    Flow rates can be 100 barrels (11.9 kl) per minute (though this could be higher or lower) and with the preferred heater trucks of the present invention, there will preferably be around a 15 degree F. (8.4° C.) increase in temperature at 100 barrels (11.9 kl) per minute (for one truck). 
         [0073]    The current normal target water temperature is 70-90 degrees F. (21.1-32.2° C.) (but it could be higher). Overheating of the water is not needed (as one must do when heating tanks) as the heat loss (if any) using the on-line heating method of the present invention is typically minimal. 
         [0074]    Maintenance of trucks used in the present invention includes chemical (e.g., hydrochloric acid) washing of the coils to keep heat transfer times low (otherwise there can be buildup on the coils which impedes heat transfer). 
         [0075]    Probably a vertical, round tank (such as mixing tank  46 ) will work better for mixing hot and cold water to get a more uniform temperature of water to use in fracing. 
         [0076]      FIG. 8  is similar to  FIG. 7 , but apparatus  310  shown therein includes a mixing tank  46  instead of the manifold  20  shown in  FIG. 7  (anything that could cause turbulence could be used instead of the manifold  20  shown in  FIG. 1 , though the manifold  20  is preferred as it is a relatively simple and compact mixing device). Water drawn from water source  11  travels through flow line  19  and first inlet  56  into mixing tank  46 , where some of the water is drawn off through second outlet  61  and line  41  into mobile heater  12 , then back through flow line  42  and second inlet  62  into mixing tank  46 , where it then continues to flow through first outlet  57  and flow line  19  to mixing tanks  46  which are near frac pumping apparatus  17 . From there the water flows as in  FIG. 7 . It is believed that better mixing of water occurs in tank  46  when first inlet  56  is near the bottom of tank  46 , first outlet  57  is near the top of tank  46 , and second inlet  62  is somewhere in between. Also, it is believed that better mixing will occur if mixing tank  46  is a vertical cylindrical tank as shown in the drawings. 
         [0077]      FIG. 9  is similar to  FIG. 8 , but apparatus  410  shown therein includes a half manifold  120  and a mixing tank  46  instead of the manifold  20  shown in  FIG. 1 . As indicated in  FIG. 9 , water at the temperature of the water source  11  flows through half manifold  120 , where some of the water is diverted out through second outlet (conduit)  31  of half manifold  120  into flow line  41  and to heater  12 , then out through flow line  42  into second inlet  62  of mixing tank  46 . The heated water from line  42  mixes in mixing tank  46  with the water which is at the temperature of water source  11  which enters tank  46  at first inlet  56 . The water then flows out through first outlet  57  through flow line  19  to mixing tanks  46  which are near frac pumping apparatus  17 . From there the water flows as in  FIG. 7 . 
         [0078]      FIG. 10  shows apparatus  510 , which includes three mobile heaters  12  with three manifolds  20 , two mobile heaters  12  in parallel with one another and located near the water source  11 , and one mobile heater  12  closer to the frac pumping apparatus  17 . There are three surge tanks  46  in series with one of the mobile heaters  12 , though these surge tanks  46  could be in series with both mobile heaters  12  which are in parallel to one another, or they could be in series with all three mobile heaters  12  shown in  FIG. 10 . Further, there could be as few as none or one surge tank  46  to as many as considered prudent by the operator, which could be for example three or four up to 50 or 100 mixing tanks  46  (or even more). Flow of water through manifolds  20 , heaters  12 , and surge tanks  46  is as in prior figures. 
         [0079]      FIG. 11  shows apparatus  610 , which includes two mobile heaters  12  connected directly to the source water  11  (a pond) with the water being withdrawn from and returned to the pond. There are also three mobile heaters  12 , each connected to a mixing tank  46 , heating water in the mixing tanks  46 . Further, there could be as few as none or one surge tank  46  and associated mobile heaters  12  to as many as considered prudent by the operator, which could be for example three or four up to 50 or 100 mixing tanks  46  with associated mobile heaters  12  (or even more). 
         [0080]      FIG. 12  is similar to  FIG. 11 , but in  FIG. 12  apparatus  710  differs from apparatus  610  in that one truck has moved from the pond  11  and is heating the water as it runs through the flow line  19 .  FIG. 12  shows three additional mixing tanks  46  in series with pipe  19  and acting as surge tanks. As in  FIG. 11 , there are also three mobile heaters  12 , each connected to a mixing tank  46 , heating water in the mixing tanks  46 . 
         [0081]    These mixing tanks  46  are in series with one another in a flow line  119  which runs parallel to flow line  19  and then feeds into flow line  19 . Further, there could be as few as none or one surge tank  46  and associated mobile heaters  12  to as many as considered prudent by the operator, which could be for example three or four up to 50 or 100 mixing tanks  46  with associated mobile heaters  12  (or even more). 
         [0082]    There is a huge lake (Lake Sakakawea) in the middle of western North Dakota. Fracing operations were making a tremendous strain on groundwater. Now it is expected that water will be pulled from Lake Sakakawea with permits currently in process. It is believed that companies will soon pump water out of Lake Sakakawea and put it into insulated tanks, where it will be heated in the tanks. The water will then be taken via insulated trucks to a well site where fracing operations occur. The apparatus of the present invention can heat water as it is pumped from the lake into the tanks (and it can continue to heat the water once it is in the tanks). This method can occur in other areas as well. 
         [0083]    The following is a list of parts and materials suitable for use in the present invention: 
         [0000]    
       
         
               
             
               
               
             
               
               
             
           
               
                   
               
               
                 PARTS LIST 
               
             
          
           
               
                 Parts Number 
                 Description 
               
               
                   
               
             
          
           
               
                 10 
                 hydraulic fracturing pumping system 
               
               
                 11 
                 water source 
               
               
                 12 
                 mobile heater apparatus 
               
               
                 13 
                 truck 
               
               
                 14 
                 trailer 
               
               
                 15 
                 vessel 
               
               
                 16 
                 oil and/or gas well 
               
               
                 17 
                 frac pumping apparatus 
               
               
                 18 
                 trailer 
               
               
                 19 
                 flow line 
               
               
                 20 
                 mixer 
               
               
                 21 
                 tubular/cylindrically-shaped body 
               
               
                 22 
                 wall 
               
               
                 23 
                 bore 
               
               
                 24 
                 inlet end portion 
               
               
                 25 
                 outlet end portion 
               
               
                 26 
                 inlet 
               
               
                 27 
                 outlet 
               
               
                 28 
                 arrow 
               
               
                 29 
                 arrow 
               
               
                 30 
                 curved arrow 
               
               
                 31 
                 conduit (second outlet) 
               
               
                 32 
                 conduit (second inlet) 
               
               
                 33 
                 bore 
               
               
                 34 
                 bore 
               
               
                 35 
                 inner end portion 
               
               
                 36 
                 outer end portion 
               
               
                 37 
                 inner end portion 
               
               
                 38 
                 outer end portion 
               
               
                 39 
                 arrow 
               
               
                 40 
                 arrow 
               
               
                 41 
                 flow line 
               
               
                 42 
                 flow line 
               
               
                 43 
                 flow line 
               
               
                 44 
                 flow line 
               
               
                 45 
                 surge tank 
               
               
                 46 
                 mixing tank or downhole tank or surge tank 
               
               
                 47 
                 joint of pipe 
               
               
                 56 
                 inlet (first) of mixing tank 46 
               
               
                 57 
                 outlet (first) of mixing tank 46 
               
               
                 61 
                 second outlet of mixing tank 46 
               
               
                 62 
                 second inlet of mixing tank 46 
               
               
                 110 
                 hydraulic fracturing pumping system 
               
               
                 112 
                 prior art mobile heating truck 
               
               
                 119 
                 flow line 
               
               
                 120 
                 half manifold 
               
               
                 210 
                 hydraulic fracturing pumping system 
               
               
                 310 
                 hydraulic fracturing pumping system 
               
               
                 410 
                 hydraulic fracturing pumping system 
               
               
                 510 
                 hydraulic fracturing pumping system 
               
               
                 610 
                 hydraulic fracturing pumping system 
               
               
                 710 
                 hydraulic fracturing pumping system 
               
               
                   
               
             
          
         
       
     
         [0084]    All measurements disclosed herein are at standard temperature and pressure, at sea level on Earth, unless indicated otherwise. 
         [0085]    The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.