Patent Application
20140083408
The following relates generally to oil and gas production, and more specifically to methods and devices for heating a liquid for injection into a wellbore or into a pipeline system.
In connection with production of oil or gas from a geological formation, a wellbore is typically drilled using subterranean drill bits, and the wellbore is typically lined with a casing that is cemented into the wellbore. After the wellbore is completed, hydraulic fracturing, also known as “fracing” may be employed to create and/or restore small fractures in the formation to stimulate production from new and existing oil and gas wells. The fractures can form conduits that enable the oil or gas to flow more easily from the tight sands or shales to the wellbore.
A common method to create fractures in the formation is to pump a fracturing 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. With each crack or fracture, the fracturing fluid can continue further into the formation, extending the crack further and further into the formation. The extended fractures create sufficient permeability to facilitate the flow of formation fluids to the well.
The fracturing fluid typically includes a slurry of proppants, water and optional chemical additives. The proppants, such as grains of sand, ceramic, and/or other particulates, are adapted to maintain fracture width, or at least slow its decline, and provide porosity to allow the formation fluids to flow out of the formation. The water is often heated to a target temperature (e.g., 40° F. to 120° F. (4.4° C. to 48.9° C.)) before the fracturing fluid is injected into the wellbore. The target temperature may depend on the geologic formation and chemicals used. 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 available water sources are typically at unsuitably code temperatures for the fracturing process. It is therefore desirable to heat the available water to a temperature suitable for the fracturing process prior to the water and fracturing fluids being pumped down the borehole.
Various aspects of the present disclosure include super heater systems adapted to efficiently heat large quantities of liquid for use in fracturing fluids. According to at least some embodiments, such super heater systems can include a fuel storage and supply system in fluid communication with a burner manifold. The burner manifold can be adapted to generate heat by combusting fuel received from the fuel storage and supply system. At least one pump may be in fluid communication with a heat exchanger assembly. The heat exchanger assembly may include a first header at a first longitudinal end. The first header can include a plurality of first header layers in alternating fluid communication. A second header at a second longitudinal end can include a plurality of second header layers in alternating fluid communication. A plurality of heat exchange coils may extend between and may be coupled to the first header and the second header. The plurality of heat exchange coils may be exposed to the heat generated by the burner manifold.
Additional aspects of the present disclosure include a burner boxes employable in a super heater system. In one or more embodiments, a burner box may include a plurality of heat exchange coils, with a first header coupled to a first longitudinal end of the heat exchange coils, and a second header coupled to an opposing longitudinal end of the heat exchange coils. The first header and the second header can each include a plurality of header layers in alternating fluid communication.
Further aspects of the present disclosure include heat exchanger assemblies adapted for use with a super heater system. In at least some embodiments, a heat exchanger assembly can include a plurality of heat exchange coils, with a first header coupled to a first longitudinal end of the heat exchange coils, and a second header coupled to an opposing second longitudinal end of the heat exchange coils. The first header can include a plurality of header layers, where at least some of the header layers of the first header are in fluid communications with at least one other header layer of the first header. The second header can also include a plurality of header layers, where at least some of the header layers of the second header are in fluid communication with at least one other header layer of the second header.
Other aspects of the present disclosure include methods of making a super heater system. One or more implementations of such methods may include forming a first header to include a plurality of header layers disposed in alternating fluid communication. A second header can also be formed to include a plurality of header layers disposed in alternating fluid communication. A longitudinal end of a plurality of heat exchange coils can be coupled to the first header and an opposing longitudinal end of the plurality of heat exchange coils to the second header.
Still additional aspects of the present disclosure include operational methods of a heat exchanger assembly. At least one implementation of such methods may include introducing a liquid into a header layer of a first header. The liquid can be caused to flow from the header layers of the first header, through a plurality of heat exchange coils into a header layer of a second header. The liquid can further be caused to flow from the header layer of the second header to another header layer of the second header. From the other header layer of the second header, the liquid can be caused to flow through another plurality of heat exchange coils to another header layer of the first header.
Other aspects, embodiments, and features within the scope of the present disclosure will become apparent to those of ordinary skill in the art upon reviewing the following detailed description.
The illustrations presented herein are, in some instances, not actual views of any particular heat exchanger assembly, heat exchange coils, headers, housing, outlet interface assembly, or super heater system, but are merely idealized representations which are employed to describe the present disclosure. Additionally, elements common between figures may retain the same numerical designation.
Various embodiments of the present disclosure comprise super heater systems with heat exchanger assemblies adapted to facilitate fluid heating at relatively high flow rates. Referring to
A pump 110 can be placed in fluid communication with the burner box 108 for providing unheated fluid to the burner box 108. In some embodiments, the super heater system 100 further includes a boost pump 112 adapted to provide additional pumping capabilities to the system. The pump 110, and optionally the boost pump 112, is/are used to draw a fluid (e.g., water) from a fluid source (e.g., a frac tank, an open reservoir often referred to as a pit by those of skill in the art) and supply the fluid to one or more components of the burner box 108. In at least some embodiments, the pump 110, in combination with or independent from the boost pump 112, can be adapted to pump the fluid into the burner box 108 at a rate greater than about 25 barrels (e.g., about 1,050 gallons, 3,974 liters) per minute. In some embodiments, the fluid can be pumped into the burner box 108 at a rate of about 30 barrels (e.g., about 1,260 gallons, 4,770 liters) or more per minute.
In some instances, a hydraulic fracturing crew (frac crew) will use between about 30 barrels (e.g., about 1,260 gallons, 4,770 liters) and 50 barrels (e.g., about 2,100 gallons, 7,949 liters) of heated liquid per minute in the fracturing process. According to an aspect of the present disclosure, the super heater system 100 is capable of heating fluid to a target temperature (e.g., between about 40° F. and 120° F. (4.4° C. to 48.9° C.)) at a rate of about 30 barrels (e.g., about 1,260 gallons, 4,770 liters) or more per minute. In some embodiments, the super heater system 100 is capable of heating the fluid to the desired temperature at a rate between 30 barrels (e.g., about 1,260 gallons, 4,770 liters) and 58 barrels (e.g., about 2,436 gallons, 9,221 liters) per minute.
In order to facilitate heating such relatively high rates of liquid to a target temperature, the burner box 108 includes a housing 114 sized and configured to accommodate a heat exchanger assembly adapted to receive and heat such sufficiently high liquid flows.
The heat exchange coils 204 can extend over a burner manifold 210 that is in fluid communication with the fuel storage and supply system 106 (see
The heat exchange coils 204 may each be formed of a material adapted to suitably facilitate conductive heat transfer (e.g., a non-insulative material), such as a metal, metal alloy, etc. In one or more embodiments, the heat exchange coils 204 are each formed of a pipe, such as a schedule 80, 2-inch (5.08 centimeters) pipe, in at least substantially equal lengths between about 15 feet (4.572 meters) and about 30 feet (9.144 meters). In at least one embodiment, the heat exchange coils 204 are each formed from a pipe of about 21.25 feet (6.477 meters) in length.
The first and second headers 206, 208 can include a plurality of header levels or layers 212. For instance, the first header 206 in the illustrated embodiment includes six (6) header layers (or first header layers) 212A through 212F, and the second header 208 also includes similar header layers (or second header layers) 212. Although six header layers 212 are illustrated, other embodiments may include different numbers of header layers. In at least some embodiments, each header layer 212 is generally shaped as a hollow cuboid in which six faces enclose, or at least substantially enclose, a hollow volume through which liquid can flow. However, other embodiments may employ different shapes for the header layers 212. The header layers 212 may be formed of a material similar to the heat exchange coils 204. For example, the header layers 212 may be formed from a metal, metal alloy, etc. Each header layer 212 of a respective header 206 or 208 is positioned one above another as illustrated.
Each of the heat exchange coils 204 is coupled to a header layer 212 of the first header 206 and the second header 208. By way of example and not limitation, the heat exchange coils 204 can be coupled to a layer of the first header 206 and the second header 208 by various means, such as a threaded connection, a weld, an adhesive, etc., as well as one or more combinations. With a generally cuboid shape (or other shape with sufficient surface area) each header layer 212 can include multiple sublayers of heat exchange coils 204 coupled thereto in some embodiments. For example, the header layer 212A of the first header 206 includes two sublayers of heat exchange coils 204, a lower layer 204A and an upper layer 204B. These sublayers are more clearly shown in
According to an aspect of the present disclosure, some of the header layers 212 are positioned in fluid communication with another header layer 212 of the same header 206 or 208 so that the liquid to be heated can flow from one header layer 212 to another. Furthermore, some of the header layers 212 are positioned without direct fluid communication with a header layer 212 directly above and/or below.
At least one of the headers 206, 208 includes an inlet for receiving liquid from the pump 110 (see
The header layers 212 of the second header 208 are also configured in alternating fluid communication. As shown, the first (or lowest) header layer 212G is in fluid communication with the header layer 212H positioned directly above by means of the conduit 310, but the header layer 212H is not in fluid communication with the above header layer 212I. The header layer 212I is in fluid communication with the header layer 212J directly above by means of the conduit 312, and the header layer 212J is not in fluid communication with the next upward header layer 212K. Finally, the header layer 212K is in fluid communication with sixth (or highest) header layer 212L via the conduit 314.
The alternating fluid communication for the header layers 212 of the first header 206 can be configured to alternate with the alternating fluid communication of the header layers 212 of the second header 208. For instance, as can be seen in
The alternating fluid communication configuration facilitates the flow of liquid through the heat exchanger assembly 202.
When the lowest header layer 212G of the second header 208 is filled, the liquid can flow into the next upward header layer 212H of the second header 208 through the conduit 310 (see
When the header layer 212B of the first header 206 is filled, the liquid can flow into the next upward header layer 212C of the first header 206 through the conduit 306 (see
When the header layer 212I of the second header 208 is filled, the liquid can flow into the next upward header layer 212J of the second header 208 through the conduit 312 (see
When the header layer 212D of the first header 206 is filled, the liquid can flow into the next upward header layer 212E of the first header 206 through the conduit 308 (see
When the header layer 212K of the second header 208 is filled, the liquid can flow into the highest header layer 212L of the second header 208 through the conduit 314 (see
In the depicted example, the liquid can flow through each of the heat exchange coils 402, 404, 406, 408, 410, 412 in parallel. Flowing in parallel refers to the concept that different volumes of liquid flow through each heat exchange coil of a given header layer 212 without flowing through any of the other heat exchange coils for that layer. For instance, a volume of liquid that flows through one of the heat exchange coils 402 will generally not flow through any of the other heat exchange coils 402. At the same time that the volume of liquid is flowing through the particular one of the heat exchange coils 402, different volumes of liquid will flow through each of the other heat exchange coils 402.
Each time the liquid passes through the heat exchange coils 402, 404, 406, 408, 410, 412, the liquid passes over the burner manifold 210. When the burner manifold 210 is lit, the liquid flowing through the heat exchange coils is exposed to heat from flames of the burner manifold 210, increasing the temperature of the liquid. In one or more embodiments, the temperature of the liquid can be increased by approximately 30°-85° F. at a rate between about 30 barrels (1,260 gallons, 4,770 liters) per minute to 58 barrels (2,436 gallons, 9,221 liters) per minute of continuous pumping flow. The change in temperature at least partially dependent on the flow rate. For example, at a low flow rate of about 10 barrels (420 gallons, 1,589 liters) per minute, the temperature of the liquid may be increased by as much as about 175° F. In another example, a flow rate of about 30 barrels (1,260 gallons, 4,770 liters) per minute may result in an increase in the temperature of the liquid by as much as approximately 85° F. In yet another example, a flow rate of about 50 barrels (2,100 gallons, 7,949 liters) may result in an increase in the temperature of the liquid by as much as about 30° F.
The heat exchanger assembly 202 can be enclosed within the housing 114 (see
The housing 114 includes at least one rib 504 coupled to a sidewall 506 of the housing 114. The at least one rib 504 is adapted to stiffen the sidewall 506 to which it is coupled. One or more ribs 504 can be coupled to an outside surface (as illustrated) and/or an inside surface of the sidewall 506. The one or more ribs 504 are disposed on the sidewall to run generally in a direction of the grain of the sidewall 506. In the illustrated example, the grain of the material used for the sidewall 506 runs generally horizontal as depicted by the arrows 508. Accordingly, the one or more ribs 504 are disposed on the sidewall to run generally in the same horizontal direction. The ribs 504 can strengthen the sidewalls 506 to inhibit or even eliminate distortion of the sidewalls 506 resulting from heat inside the burner box 108.
According to an aspect of the present disclosure, one or more embodiments of the super heater system 100 may further include an outlet interface assembly providing a plurality of outlets.
The on-the-fly outlet interface 604 is sized and configured to facilitate a full flow of the heated liquid. In some implementations, the on-the-fly outlet interface 604 may be employed to connect a discharge hose for immediate or approximately immediate use of the heated liquid by a frac crew. That is, since the super heater system 100 is able to heat the liquid to the target temperature at flow rates about equal to or even above the rate at which the heated liquid is being pulled by a frac crew, the heated liquid can be employed by the frac crew on-the-fly (i.e., without the use of preheated stockpiles of liquid) or substantially on-the-fly.
The plurality of preheat outlet interfaces 606 enables the super heater system 100 to connect a plurality of discharge hoses. The plurality of preheat outlet interfaces 606 may be employed for heating a liquid that is to be stored (or stockpiled) prior to being used by a frac crew. For example, the plurality of preheat outlet interfaces 606 may be employed for coupling a plurality of discharge hoses to one or more frac tanks. In other examples, the plurality of preheat outlet interfaces 606 can be employed to control the flow of the heated liquid into the storage container. For example, a super heater system 100 may be employed for heating a large open reservoir, typically referred to as a pit. To blend the heated water with the rest of the water in the reservoir, a current can be induced into the reservoir to circulate the water using a plurality of discharge hoses respectively coupled to the plurality of preheat outlet interfaces 606 and strategically placed in the reservoir.
Further embodiments of the present disclosure relate to methods of making a super heater system including a heat exchanger assembly, such as the super heater system 100 including the heat exchanger assembly 202 as described above.
At step 706, a plurality of heat exchange coils (e.g., heat exchange coils 204 in
At step 708, a burner manifold (e.g., burner manifold 210 in
At step 710, a housing (e.g., housing 114 in
Although not depicted in
The various features associate with the examples described herein and shown in the accompanying drawings can be implemented in different embodiments and implementations without departing from the scope of the present disclosure. Therefore, although certain specific constructions and arrangements have been described and shown in the accompanying drawings, such embodiments are merely illustrative and not restrictive of the scope of the disclosure, since various other additions and modifications to, and deletions from, the described embodiments will be apparent to one of ordinary skill in the art. Thus, the scope of the disclosure is only determined by the literal language, and legal equivalents, of the claims which follow.
