Patent Publication Number: US-6338381-B1

Title: Heat exchange systems

Description:
RELATED APPLICATION 
     This is a continuation-in-part of U.S. Application Ser. No. 09/504,172 filed Feb. 15, 2000, now U.S. Pat. No. 6,267,172 incorporated fully herein for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention, in at least certain embodiments, is directed to heat exchange systems for exchanging heat between an earth conduit and/or earth loop and a rig, wellhead, pipe, pipeline or riser; the systems, in certain aspects, having an earth conduit or loop and associated apparatus for transferring heat between transfer fluid circulating in the conduit or loop and the rig, wellhead, pipe, pipeline or riser. 
     2. Description of Related Art 
     The prior art discloses a wide variety of earth heat exchange systems. Typically such systems include conduit, conduits, and/or a pipe loop within the earth, apparatus for circulating heat transfer fluid therethrough and through other systems or apparatuses above the surface, and heat exchange apparatus for exchanging heat between the transfer fluid and an item, apparatus, device or other thing. 
     SUMMARY OF THE PRESENT INVENTION 
     The present invention, at least in certain preferred aspects, discloses a system for heating or cooling a rig, apparatus thereon, a pipeline (above ground, under ground, and/or under water), wellhead, pipe, wellbore or a riser, the system including an earth heat exchange conduit or loop within the earth and heat exchange apparatus for conveying heated (or cooled) transfer fluid circulating through the earth heat exchange conduit or loop to the rig, pipe, wellbore, riser, or pipeline. The heat exchange apparatus may encompass a portion of an item&#39;s exterior and/or it may include heat exchange device(s) within the item or pipeline to heat or cool fluid flowing therein. 
     In certain embodiments according to the present invention the heat exchange apparatus is permanently or semi-permanently installed on a pipe, rig, riser, wellhead or pipeline section. In other embodiments a movable jacket or module is used that is selectively interconnectible to one of a series of earth heat exchange conduits or loops so that a selected portion of the item or section can be heated or cooled. In another aspect a mobile heat exchange apparatus is used within a pipe, riser, or a pipeline that can be connected so that it is in fluid communication with an earth heat exchange system nearby. In certain embodiments one or more flow rate control devices are used within a conduit or loop to control and/or maintain fluid flow rate through a portion thereof. 
     In one aspect an earth conduit or loop is provided that has a portion thereof that is insulated. In another aspect one or more valves and/or one or more flow rate control devices are used in an earth conduit or loop to control fluid flow rate therein and/or to selectively flow heat transfer fluid through a selected portion of a loop or conduit. 
     What follows are some of, but not all, the objects of this invention. In addition to the specific objects stated below for at least certain preferred embodiments of the invention, other objects and purposes will be readily apparent to one of skill in this art who has the benefit of this invention&#39;s teachings and disclosures. It is, therefore, an object of at least certain preferred embodiments of the present invention to provide: 
     New, useful, unique, efficient, nonobvious devices and methods for transferring heat between a rig, wellhead, or pipeline and heat transfer fluid circulating through an earth conduit or loop; 
     Such devices and methods wherein a heat exchange device is selectively emplaceable at a desired location and removably interconnectible with one, two, three, or more or a series of a plurality of earth conduits and/or loops; 
     Such devices and methods with remotely controlled controllers, pumps, etc; 
     Such devices and methods with pumps, etc. powered with a solar power system and/or a wind power system; 
     Such devices and methods for a portion of a pipeline above ground and/or below ground; 
     Such devices and methods with a heat exchange device on the outside of or within a pipeline; 
     Such devices and methods with a heat exchange device movable within a pipeline; 
     Such devices and methods with a heat exchange device within a wellbore, the device in fluid communication with an earth conduit or loop; 
     Such devices and methods with an earth conduit or earth loop having an insulated portion to enhance heat transfer efficiency; and 
     Such devices and methods with one or more pumps, valves, and/or flow control devices in an earth conduit or loop, or in part thereof, or in an earth loop with one or more crossover portions. 
     Certain embodiments of this invention are not limited to any particular individual feature disclosed here, but include combinations of them distinguished from the prior art in their structures and functions. Features of the invention have been broadly described so that the detailed descriptions that follow may be better understood, and in order that the contributions of this invention to the arts may be better appreciated. There are, of course, additional aspects of the invention described below and which may be included in the subject matter of the claims to this invention. Those skilled in the art who have the benefit of this invention, its teachings, and suggestions will appreciate that the conceptions of this disclosure may be used as a creative basis for designing other structures, methods and systems for carrying out and practicing the present invention. The claims of this invention are to be read to include any legally equivalent devices or methods which do not depart from the spirit and scope of the present invention. 
     The present invention recognizes and addresses the previously-mentioned problems and long-felt needs and provides a solution to those problems and a satisfactory meeting of those needs in its various possible embodiments and equivalents thereof. To one skilled in this art who has the benefits of this invention&#39;s realizations, teachings, disclosures, and suggestions, other purposes and advantages will be appreciated from the following description of preferred embodiments, given for the purpose of disclosure, when taken in conjunction with the accompanying drawings. The detail in these descriptions is not intended to thwart this patent&#39;s object to claim this invention no matter how others may later disguise it by variations in form or additions of further improvements. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     A more particular description of embodiments of the invention briefly summarized above may be had by references to the embodiments which are shown in the drawings which form a part of this specification. These drawings illustrate certain preferred embodiments and are not to be used to improperly limit the scope of the invention which may have other equally effective or legally equivalent embodiments. 
     FIG. 1 is a schematic view in cross-section of a system according to the present invention. 
     FIG. 2 is a schematic view in cross-section of a system according to the present invention. 
     FIG. 3 is a schematic view in cross-section of a system according to the present invention. 
     FIG. 4 is a schematic view in cross-section of a system according to the present invention. 
     FIG. 5 is a schematic view in cross-section of a system according to the present invention. 
     FIG. 6 is a schematic view in cross-section of a system according to the present invention. 
     FIG. 7 is a schematic view in cross-section of a system according to the present invention. 
     FIG. 8 is a schematic view in cross-section of a system according to the present invention. 
     FIGS. 9A and 9B are schematic views in cross-section of systems according to the present invention. 
     FIG. 10 is a schematic view in cross-section of a system according to the present invention. 
     FIG. 11 is a schematic view in cross-section of a system according to the present invention. 
     FIG. 12 is a schematic view in cross-section of a system according to the present invention. 
     FIG. 13 is a schematic view in cross-section of a system according to the present invention. 
     FIG. 14 is a schematic view in cross-section of a system according to the present invention. 
     FIG. 15 is a schematic view of a system according to the present invention. 
    
    
     DESCRIPTION OF EMBODIMENTS PREFERRED AT THE TIME OF FILING FOR THIS PATENT 
     Referring now to FIG. 1, a system  10  according to the present invention includes an earth heat loop  12  made of any suitable conduit or pipe material through which a heat transfer fluid can be circulated. The loop  12  extends down into the earth E to a desired depth, e.g., but not limited to, a depth at which the temperature of the earth is between 60° F. and 80° F. Higher (and lower) temperatures can often be encountered at various depths in the earth and any loop (or earth conduit) disclosed herein may extend to such depths as desired. 
     A pump  14  pumps the heat transfer fluid through the loop  12  and through a heat exchange apparatus, e.g. but not limited to, a conduit  16 , a portion of which encompasses a portion of a pipeline  18  through which fluid flows. Alternatively, or in addition to the pump  14 , a pump  19  beneath the earth&#39;s surface pumps fluid through the loop  12  and the conduit  16 . The conduit  16  is in fluid communication with the loop  12  so that heat transfer fluid is pumped through the loop  12  to the conduit  12 , and back through the loop  12  continuously. 
     In situations in which the temperature of the environment of the pipeline is relatively cold, e.g. but not limited to 32° F. or below, or 0° F. or below, the heat transfer fluid is pumped through a loop  12  to a sufficient depth and the loop is of sufficient length that the fluid is warmed and then, by heat exchange, warms the portion of the pipeline  18  and, hence, fluid within that portion of the pipeline. The conduit  16  can be any desired length. Optionally, insulation  17  is provided around the conduit  16  and/or the pump  14 . Also, as described below, part of the loop under the earth&#39;s surface may be insulated. In situations in which the pipeline&#39;s environment is relatively hot, e.g., but not limited to 100° F. or hotter, the heat transfer fluid at a cooler temperature, e.g. between about 70° F. to 80° F., can be used to cool, by heat exchange, the portion of the pipeline  18  encompassed by the conduit  16 . 
     FIG. 2 illustrates a system  20  according to the present invention in which a pipeline  28  is buried in the earth E. An earth loop  22  has a lower portion in fluid communication with an upper heat exchange portion  26  that encompasses a part  23  of the pipeline  28 . The part  23  of the pipeline  28 , and hence fluid in that part of the pipeline, may be at one temperature while heat transfer fluid with a pump  24  pumped through the loop  22  is of a different temperature. Thus, as with the system  10 , by circulating heat transfer fluid through the loop  22  and the conduit  26  the part  23  of the pipeline can be cooled or heated, depending on the temperature differential of the earth adjacent the loop  12  and adjacent the part  23  of the pipeline, and depending on the temperature of fluid flowing through the pipeline. Alternatively, a portion of the conduit  26  or loop  22  can extend above the earth surface and a pump can be positioned there to circulate fluid through the loop and the conduit. Either a sufficient length of conduit  16  or  26  are used, or an appropriate heat exchange apparatus in fluid communication with the conduit is used, to effect a desired temperature change for a pipeline portion and/or fluid flowing through the pipeline portion. 
     FIG. 3 illustrates a system  30  for a pipeline  38  above the earth E that includes three earth loops  32   a,    32   b,    32   c  which extend down into the earth E to a desired depth which is at a desired temperature. Associated with and in fluid communication with each earth loop is a heat exchange apparatus, e.g., but not limited to conduits  36   a,    36   b,    36   c  each of which is in fluid communication with a corresponding earth loop. It is within the scope of this invention for the pipeline  38  to be buried in the earth. It is within the scope of this invention to have any desired number of spaced-apart earth loops in proximity to and/or along the length of the pipeline. 
     A cable  31  interconnects a control apparatus  33   a  for a pump  34   a  with a control function  35  that may be near the pipeline or located remotely with respect to it. Another cable  35   a  interconnects the control apparatus  33   a  with other control apparatuses  33   b  and  33   c.  The control function can selectively activate or deactivate any, all, or any combination of the pumps  34   a,    34   b,    34   c  to selectively heat (or cool) portions of the pipeline  38  corresponding to the conduits  36   a,    36   b,    36   c.    
     A sensor  39   a  in communication with the control apparatus  33   a  signals the temperature of the pipeline  38  to thermostat apparatus and associated devices in the control apparatus  33   a  to activate or deactivate the pump  34   a  at desired pre-set pipeline temperatures and/or via the cable  31  temperature information is conveyed to the control function  35  and subsequent activation or deactivation of the pump  34   a  is accomplished (and, hence, corresponding heating or cooling of the pipeline and its contents via the conduit  36   a ). Such a sensor (like the sensor  39   a ) and related apparatus may be used with each of the pumps  34   b  and  34   c  and their control apparatuses. 
     Sensor  39   b  is connected to the control apparatus  33   b  and operates in a manner similar to that of the sensor- 39   a /controller  33   a  combination; but the sensor  39   b  is inside the pipeline  38 . A sensor  39   b  and related apparatus may be used with each of the pumps  34   a,    34   c  and their control apparatuses. 
     Alternatively (or in addition to the cable  31 ) signals and data may be transmitted to and from the system  30  using wireless communication and associated transmitters and receivers at a control function (like the control function  35 ) and in the control apparatuses  33   a,    33   b,    33   c,  e.g. but not limited to, via one or more antennas  39 . 
     A suitable enclosure and/or insulation material  37 , shown enclosing the conduit  36   c  and related apparatuses, may be used with the conduits  36   a,    36   b  and related apparatuses. 
     Power for the pumps and control apparatuses of the system  30  may be provided via suitable cables or lines. Alternatively, or in addition to such power, a solar collector  41  with storage batteries  42  may be used to provide power for the system  30  and/or a wind-driven power generating system  43  with storage batteries  44  may be used. It is within the scope of this invention to provide such power source systems for any earth heat loop transfer system whether used with a pipeline or not. 
     FIG. 4 shows a system  40  according to the present invention which has an earth loop  45  through which heat transfer fluid circulates (e.g. by a pump or pumps, not shown) which is in fluid communication with a transfer fluid line  47  of a movable heat exchange tube or jacket  46  in position on a portion of a pipeline  48  above the earth E. The tube or jacket  46  can, according to the present invention, be configured and fashioned to completely encircle a portion of a pipeline or to cover only a part of its full circumference. Connection  49   a,    49   b  on the loop  45  and connections  49   c,    49   d  on the line  47  make it possible to disconnect the line  47  from the loop  45  and to re-connect the line  47  to connections  49   e,    49   f  of another loop  45   a  so that the line  47  is then in fluid communication with the loop  45   a  and heat transfer fluid can be circulated (e.g. with a pump or pumps, not shown) through the loop  45   a  and the tube or jacket  46 . It is within the scope of this invention to use any desired number of earth loops  45  and/or  45   a  in the system  40 ; and/or to use a plurality of loops of different depths to access earth areas of different temperatures to apply heat transfer fluids at one selected temperature to the pipeline. 
     FIG. 5 illustrates a system  50  with a pipeline  58  (which is either above ground or buried in the earth). An earth loop  52  (which is either completely buried in the earth and extends to a desired depth or has at least a portion buried in the earth and extending down to a desired depth which is at a desired temperature) is in fluid communication with a heat exchange apparatus  56 , which, in one aspect, is a conduit in fluid communication with the loop  52 . A pump  54  circulates fluid through the apparatus  56  and the loop  52 . A pump may also be used outside the pipeline  58  to accomplish this circulation. The system  50 , thus, heats (or cools) fluid flowing in the pipeline  58 . Any loop disclosed herein may, similarly, be interconnected with an apparatus within a pipeline like the apparatus  56 . 
     FIG. 6 shows a system  60  with a plurality of conduits  66   a,    66   b,  in a pipeline  68 . Each conduit  66   a,    66   b  is in fluid communication with a corresponding earth loop  62   a,    62   b,  part or all of which is buried in the earth down to a desired depth (as may be the pipeline  68 ). Pumps  64   a,    64   b,  respectively circulate heat transfer fluid through their respective conduit/loop combinations. It is within the scope of this invention to provide a plurality of such conduit/loop combinations in a pipeline or portion thereof. 
     FIG. 7 illustrates a system  70  according to the present invention which has a mobile heat exchange apparatus  76  movable disposed within a pipeline  78 . A line  77  partially within the apparatus  76  is, via connectors  79 , in fluid communication with an earth loop  72 . A pump  74  (which may be located outside the pipeline) circulates heat transfer fluid through the loop  72  and line  77 . The apparatus  76  may be motorized and remotely controllable so that it may be selectively positioned at a desired location in the pipeline  78 . The line  77  may be of any suitable length to allow the apparatus  76  to reach a desired point within the pipeline with respect to the connectors  79 . In another aspect the pipeline is provided with a series of spaced-apart connectors  79 , each associated with an earth loop and/or a series of spacedapart earth loops adjacent the pipeline. A remote-controlled apparatus  76  is selectively movable to any desired set of connectors within the pipeline at which a connection is made of the line  77 . The apparatus  76  then engages in a heat exchange operation within the pipeline—either in an evacuated pipeline or in a pipeline with fluid flowing, frozen, or partially frozen therein. 
     FIG. 8 illustrates a system  80  according to the present invention which includes an earth loop  82   a  through which heat transfer fluid is circulated by a pump  84   a.  The earth loop  82   a  is in fluid communication with a well loop  82   b  which extends down into a well  81  in the earth E (which may be any type of well). Optional pumping apparatus  84   b  pumps fluid out of the well  81 . Due to a temperature differential between the earth at a lower end of the loop  82   a  and the interior of the well  81 , the heat transfer fluid circulated through the loops  82   a  and  82   b  heats (or cools) the interior of the well  81  facilitating operations within the well  81 , including, but not limited to facilitating the operation of systems, devices, and apparatuses within the well  81 . Optionally via a conduit  82   c  heat transfer fluid may be circulated to and from the apparatus  84   b.  Optionally insulating material  87  and/or an insulating enclosure may be used on any part of parts of the loop  82   a  (as with any loop disclosed herein). Also, any of the above-ground apparatus and equipment may also be insulated. Any of the heat exchange systems disclosed herein (e.g. but not limited to those of FIGS. 1-8) may be used to provide heat transfer fluid to a heat exchange system which then heats or cools a pipeline, rather than to such a system that is directly in contact with a pipeline as in FIGS. 1-8. 
     FIG. 9A shows a system  90  according to the present invention for an offshore rig R above the ocean floor F. (Of course, it is within the scope of the present invention to use a system  90 , or any earth conduit or loop and associated apparatuses and devices, with a land rig.) A plurality of heat transfer loops  92   a,    92   b,    92   c  (any one or two of which may be deleted) are operatively connected to the rig R to supply heat transfer fluid of different temperatures for use on the rig R. The loops extend down below a water surface W. 
     The loops  92   b  and  92   c  extend only down into the water and do not extend into the earth E below the ocean floor. Part of the loop  92   c  is insulated with insulation  97   c  so that heat transfer fluid circulated through the loop  92   c  is primarily exposed to the temperature of the water near the ocean floor F. Appropriate pumps and control apparatuses (not shown) for all the loops are on the rig R. The loop  92   a  is within the earth and is insulated with insulation  97   a  both in the water and down to a certain depth in the earth, insuring that heat transfer fluid circulated through this loop is primarily exposed to a temperature at a desired depth in the earth. FIG. 9B shows an addition to the system  90  of FIG. 9A which includes a series of heat exchange tubes  93  around a room  91  (or apparatus) on the rig R. The tubes  93  are in fluid communication with the heat transfer loop  92   a  so that heat exchange fluid flowing therein and through the tubes  93  may heat or cool the room  91  (or apparatus). Any, some or all of the loops  92   a,    92   b, and/or  92   c  may be used for heat exchange with the room  91 . The rig R may be a land rig and then all the loops  92   a,    92   b,    92   c  would extend into the earth. 
     FIG. 10 shows a system  100  according to the present invention for a rig R 2  (like the rig R) in the ocean O above an ocean floor F 2 . A production riser or a tubular  101  extends down from the rig R 2  to a well  103  in the earth E. An earth loop  102  is in fluid communication with a heat exchange apparatus  106  that encompasses the riser or tubular  101  so that a pump  104  can pump the heat transfer fluid through the loop  102  and through the apparatus  106 . Optionally, a pump  104   a  on the rig R 2  can be used to pump the heat transfer fluid via conduits  105   a,    105   b  in fluid communication with the apparatus  106 . The apparatus  106  may be insulated with insulation  107 . 
     FIG. 11 illustrates a system  110  according to the present invention which includes an earth loop  112  in the earth E having a crossover portion A at an earth depth E 1  and a lowermost portion B at a different earth depth E 2 . Valving apparatuses V 1  initially preventing fluid flow down to the lowermost loop portion B are activatable in response to fluid pumped at a pre-determined rate. For example, when heat transfer fluid is pumped through the loop  112  (with a pump or pumps, not shown) at a rate lower than the predetermined rate, it flows through the loop portion A and is exposed to the earth&#39;s temperature at the depth E 1 . When fluid is pumped at or above the pre-determined rate, the valving apparatuses V 1  open and the heat transfer fluid flows through the loop portion B and is exposed to the earth&#39;s temperature at the depth E 2 . 
     FIG. 12 illustrates a system  120 , like the system  110 , and like numerals and symbols indicate the same items and things; but the valving apparatuses V 1  are deleted and a single valving apparatus is used that selectively allows flow either through the loop portion A (while closing off flow to the loop portion B) or through the loop portion B (while closing off flow through the loop portion A). It is within the scope of this invention to provide any earth loop herein with two or more crossovers, like the crossover portion A, and corresponding valving apparatus so that two, three, four or more portions of an earth loop are selectively accessible, thereby making it possible to access an earth depth at a desired temperature for heat transfer. Also, according to the present invention any portion of any such loop may be insulated to enhance heat transfer efficiency at a desired earth depth. 
     FIG. 13 discloses a system  120   a,  like the system  120  (and like identifying letters and numerals identify like parts), with a pump P 1  within the loop for pumping fluid through the loop. Such a pump may be disposed at any desired location in the loop and used with any loop disclosed herein. Such a pump may be remotely activated via appropriate wiring extending from the pump to the surface or the pump may be activated via a wireless system. 
     FIG. 14 illustrates a system  140  according to the present invention which has an earth heat loop within the earth having one or more flow control devices F 1  and/or F 2  for controlling fluid flow in the loop or a part thereof. In certain embodiments such a flow control device (or devices) insures that heat transfer fluid moves at an optimum rate through a loop portion to optimize heat transfer between the fluid and the earth. Any suitable flow control device may be used, including, but not limited to, known restricted opening flow restrictors, and commercially available Flosert devices from Lee Company. 
     Any earth loop in any system or method according to the present invention may be, but is not limited to, any earth heat exchange loop as disclosed in U.S. Pat. Nos. 5,590,715; 5,758,724; 5,244,037; 5,261,251; 5,671,608; 5,477,914; 5,706,888; and in Swiss Patent CH 653120A5—all such patents incorporated fully herein for all purposes. Although various preferred embodiments of the present invention are described above as using earth loops, it is within certain embodiments of the present invention to use an earth heat exchange system, e.g., but not limited to, as disclosed in U.S. Pat. Nos. 4,448,237, 4,286,651; 4,574,875; 4,912,941; 3,609,980; 4,325,228; 5,183,100; and 5,322,115 (all such patents incorporated fully herein for all purposes) through which to circulate heat transfer fluid for heat exchange with a pipeline, rig, riser, etc. according to the present invention. 
     The present invention, therefore, provides in certain, but not necessarily all embodiments, a method for exchanging heat between a pipeline through which fluid is flowable and an earth conduit through which heat transfer fluid is flowable flows, the method including flowing heat transfer fluid through a first earth conduit extending from an earth surface down into the earth and having a first conduit portion in the earth at a desired location with a desired earth temperature; emplacing heat exchange apparatus with respect to a pipeline portion of a pipeline, the heat exchange apparatus including a heat exchange device for exchanging heat with the pipeline and connection apparatus, connecting the connection apparatus in fluid communication with the heat exchange device and the first earth conduit; and flowing the heat transfer fluid through the first earth conduit and then in heat exchange relation with the heat exchange device to transfer heat between the pipeline portion and the heat transfer fluid. Such a method may include one, some or (in any possible combination) of the following: flowing fluid through the pipeline, and exchanging heat between fluid flowing through the pipeline and the heat transfer fluid; wherein the first earth conduit is a loop with an inlet through which heat transfer fluid enters the earth conduit and an outlet from which the heat transfer fluid exits the conduit; pumping the heat transfer fluid through the first earth conduit and through the heat exchange apparatus with pump apparatus; powering the pump apparatus with power generated by a solar power system; powering the pump apparatus with power generated by a wind power system; controlling the pump apparatus from a location remote from the pipeline; wherein the heat exchange device is on an exterior of the pipeline; wherein the heat exchange device is within the pipeline; wherein the first earth conduit is within a first earth bore extending down into the earth and the heat exchange device is within a wellbore spaced-apart from the first earth bore, the method also including exchanging heat between an interior of the wellbore and heat transfer fluid flowing through the heat exchange device in the wellbore; wherein a portion of the first earth conduit is insulated to enhance heat transfer efficiency between the heat transfer fluid and the heat exchange device; controlling rate of fluid flow within the first earth conduit with a flow rate controller within the first earth conduit; wherein the first earth conduit has at least two loop portions each in fluid communication with the first earth conduit for the flow therethrough of heat transfer fluid and valve apparatus controls fluid flow to the at least two loop portions, the at least two loop portions spaced apart from each other and at different levels at different temperatures in the earth, the method including selectively flowing heat transfer fluid through only one of the at least two loop portions; wherein the pipeline portion of the pipeline is underwater, above ground, or underground; wherein the pump apparatus is underwater, above ground or under ground; and/or the method including stopping heat transfer fluid flow, disconnecting the connection apparatus, re-connecting the connection apparatus between a second portion of the pipeline and a second earth conduit extending from an earth surface down into the earth and having a second conduit portion in the earth at a desired location with a desired earth temperature, and flowing the heat transfer fluid through the second earth conduit to the heat exchange device. 
     The present invention, therefore, provides in certain, but not necessarily all embodiments, a method for providing heat transfer fluid to a rig (offshore or land) involved in wellbore operations for exchanging heat between the rig (and/or apparatus or structure on the rig) and a conduit extending from the rig, the conduit extending through material having at least two areas of different temperature, the method including flowing heat transfer fluid through the conduit and to and through heat exchange apparatus on the rig, and insulating a portion of the conduit in at least one of the at least two areas of different temperature to enhance heat transfer efficiency between the heat transfer fluid and the heat exchange apparatus; wherein the rig is an offshore rig and the material includes water adjacent the rig; wherein the rig is an offshore rig and the material includes water adjacent the rig and earth below the water; wherein the rig is an offshore rig and the heat exchange apparatus includes a heat exchange device for exchanging heat between the heat transfer fluid and a riser extending down from the rig. 
     The present invention also discloses, in at least certain embodiments, systems for use in such methods. 
     FIG. 15 shows a system  200  according to the present invention which has a header  210  which distributes or collects fluids between a plurality of spaced terminals  11  and a centralized point or facility  14 . While terminals  11  (only some are numbered for clarity) can be any station or structure to which fluids are to be distributed and/or collected, they are illustrated in FIG. 15 as wellheads of production/injection wells which, in turn, have been drilled and completed at spaced locations on the earth&#39;s surface  12 . As will be understood by those skilled in this art, the spacing of the wellheads  11 , as shown in FIG. 15, is for illustration purposes only is not necessarily to scale. This spacing between wellheads  11  in actual field applications may vary from about 8 feet or less up to 120 feet or more. 
     As shown in FIG. 15, all of the wellheads  11  are fluidly connected to a single manifold or header  10  by means of respective lateral pipes  13 . Where the wells are producing wells, the production fluids (e.g. oil, gas, and/or water) from a particular well flow through its wellhead  11  and lateral pipe  13  into header  10 . The fluids commingle within the header  10  and flow through the header to a centralized location  14  for further handling. Where the wells are injection wells, the reverse is true. That is, an injection fluid (e.g. water for disposal or for use in water-flooding operations) flows from centralized location  14 , through header  10 , and out into each of the wellheads  11  through its respective lateral pipe  13 . Of course, it should be understood that certain wellheads  11  can be shut-in when the situation dictates and fluids will be produced or injected through only those wellheads that are open (i.e. on-line). 
     One of the lateral pipes  213  is shown in fluid communication with an earth heat transfer system  224  which can either cool or heat the lateral pipe  213 , and/or fluid therein, depending on the earth temperature adjacent part of a heat transfer conduit or loop  225 . The system  224  may be any earth heat transfer system with any conduit or loop disclosed herein with any associated apparatuses, heat exchangers, pumps, equipment and/or devices disclosed herein. The header  210  may be any suitable header, including, but not limited to, a header as disclosed in U.S. Pat. No. 6,062,308 issued May 16, 2000 and incorporated fully herein for all purposes. 
     An earth heat transfer system  223  (like the system  224 ) is in direct communication with one of the terminals or wellheads  211  and provides heating or cooling of the wellhead and/or of fluid therein. Any lateral pipe  213  (or all of them) may have a heating/cooling system  224  or the system  224  may be in communication with more than one lateral pipe  213 . Also, each terminal or wellhead  211  may be in fluid communication with its own system  223  or the system  223  as shown may be in communication with more than one terminal or wellhead. 
     An earth heat transfer system  222  (like the system  224 ) is in communication with the header  210  and provides for heating or cooling of fluid flowing in the header  210  and/or of the header itself. 
     An earth heat transfer system  221  (like the system  224 ) is in communication with the central facility  14  and can heat or cool part thereof and/or fluid therein. Alternatively, or in addition to these functions, fluid flowing from the central facility  14  to the header  210  may be heated or cooled by the system  221 . 
     Optionally, any, some in any combination, or all (but one) of the systems  221 - 224  may be eliminated from the system  200 . It is within the scope of this invention for the fluid flowing through the header to also be the fluid flowing through a loop or conduit of an earth heat exchange system (and similarly for the wellhead(s), pipes, and/or central terminal or facility). Also, as described herein, any portion(s) or section(s) of a loop or conduit of an earth heat exchange system of FIG. 15 may be insulated so that fluid of a desired temperature is provided for heat exchange with the header, pipe, wellhead(s), and/or central facility. 
     The present invention, provides, therefore, in some (but not necessarily all) embodiments, a system for heating or cooling a wellhead, the system including a header in fluid communication via a pipe with a wellhead (or directly with the wellhead with the pipe omitted) so that header heat transfer fluid is flowable from the header through the pipe (if it is present), to the wellhead and back through the pipe to the header, an earth heat exchange system with earth heat exchange fluid flowable therethrough to provide heat exchange between the earth heat exchange fluid and the earth, and the earth heat exchange fluid flowable in heat exchange relation to heat or cool the wellhead and/or fluid in it. Such a system may include one or some (in any possible combination) of the following: the earth heat exchange fluid flowable in heat exchange relation to heat or cool the header; wherein heating or cooling the header effects corresponding heating or cooling of the header heat transfer fluid; wherein heating or cooling the header effects corresponding heating or cooling of fluid in the wellhead; the earth heat exchange system fluid flowable in heat exchange relation to heat or cool the pipe; wherein heating or cooling the header effects corresponding heating or cooling of fluid in the pipe; a central facility in fluid communication with the header, pipe, and/or wellhead; the earth heat exchange system fluid flowable in heat exchange relation to heat or cool the central facility; wherein heating or cooling the header effects corresponding heating or cooling of fluid in the central facility; and/or wherein the fluid in the central facility is header heat exchange transfer fluid flowing to and through the central facility. 
     The present invention, provides, therefore, in some (but not necessarily all) embodiments a system for heating or cooling a plurality of wellheads, the system including a header in fluid communication via a plurality of pipes with each wellhead of the plurality of wellheads so that header heat transfer fluid is flowable from the header to the wellheads and back to the header, an earth heat exchange system with earth heat exchange fluid flowable therethrough to provide heat exchange between the earth heat exchange fluid and the earth, and the earth heat exchange fluid flowable in heat exchange relation to heat or cool each wellhead. 
     The present invention, provides, therefore, in some (but not necessarily all) embodiments a method for heating or cooling at least one wellhead, the method including flowing earth heat exchange fluid of a system in heat exchange relation to effect heating or cooling of the at least one wellhead, the system having a header in fluid communication via a (optional) pipe with a wellhead so that header heat transfer fluid is flowable from the header to the wellhead and back to the header, an earth heat exchange system with earth heat exchange fluid flowable therethrough to provide heat exchange between the earth heat exchange fluid and the earth, and the earth heat exchange fluid flowable in heat exchange relation to heat or cool the wellhead; and such a method wherein the at least one wellhead is a plurality of wellheads each in fluid communication with the header. 
     In conclusion, therefore, it is seen that the present invention and the embodiments disclosed herein and those covered by the appended claims are well adapted to carry out the objectives and obtain the ends set forth. Certain changes can be made in the subject matter without departing from the spirit and the scope of this invention. It is realized that changes are possible within the scope of this invention and it is further intended that each element or step recited in any of the following claims is to be understood as referring to all equivalent elements or steps. The following claims are intended to cover the invention as broadly as legally possible in whatever form it may be utilized. The invention claimed herein is new and novel in accordance with 35 U.S.C. § 102 and satisfies the conditions for patentability in § 102. The invention claimed herein is not obvious in accordance with 35 U.S.C. § 103 and satisfies the conditions for patentability in § 103. This specification and the claims that follow are in accordance with all of the requirements of 35 U.S.C. § 112. The inventors may rely on the Doctrine of Equivalents to determine and assess the scope of their invention and of the claims that follow as they may pertain to apparatus not materially departing from, but outside of, the literal scope of the invention as set forth in the following claims.