Patent Application
20130186132
The present invention relates generally to the recovery of raw stranded and liquid rich natural gas, producible or produced by a hydrocarbon well, and more particularly, relating to a system and method for the capture, conditioning, compression and transportation of such gas for the purpose of powering equipment with such gas that otherwise would simply be left unproduced or vented, as waste, to atmosphere.
Natural gas is a widely used energy source in many applications. Conventionally, natural gas is captured from a natural gas producing hydrocarbon well and is transported along a pipeline from the well to a processing facility where the nature gas is processed to remove impurities to the specifications of a marketable natural gas. The marketable gas, which is either low pressure sales gas, liquefied natural gas (LNG) or compressed natural gas (CNG), is then transported and distributed as required. However, in low natural gas producing wells or wells that are too remote to be connected to a gas pipeline, the natural gas is deemed stranded and is often vented to atmosphere. It is estimated that a significant amount of useable natural gas is vented to atmosphere each year, resulting in a considerable waste of the world's natural gas resources. Venting of the natural gas also increases greenhouse gas emissions and the loss of recoverable hydrocarbons and other fluids and chemicals that are carried by the vented natural gas into the atmosphere.
The costs of running mobile and transportable equipment powered by diesel engines can be reduced by displacing an amount of diesel fuel with processed natural gas for the purpose of reducing the amount of diesel fuel that must be consumed by operating the diesel engine. Such fuel systems are commonly referred to as a “Bi-Fuel” system, and are readily known in the art. An additional benefit for using natural gas as engine fuel on diesel engines include a cleaner burning engine, reduced greenhouse gas emissions and reduced operating and maintenance costs. However, the utilization of processed natural gas in Bi-Fuel systems for diesel engines operating mobile and transportable equipment is widely limited to equipment located at sites having a connection to a gas pipeline.
Accordingly, there is a need to capture vented raw natural gas from natural gas producing wells that are too remote to be connected to a gas pipeline. Additionally, there is a need to utilize natural gas at wellsites or facilities too remote to be connected to a gas pipeline as a fuel source in operating diesel engines located at the wellsite or facility.
Embodiments of the present invention addresses this need by providing a system and method for the onsite capture, conditioning and compressing of raw stranded natural gas produced or producible at a wellsite or facility; the transport of the conditioned and compressed natural gas to a second wellsite or facility; and onsite the second wellsite or facility the depressurizing, fluid recovery and consumption of the natural gas by a combustion engine having a Bi-Fuel.
Embodiments of the present invention also provide a system and method for fueling mobile and transportable equipment, containing one or more diesel engines, with a mixture of natural gas and diesel fuel.
Embodiments of the present invention also provide a system and method for fueling gas fired equipment, directly with natural gas.
Embodiments of the present invention also provide a processing system and method including a rich natural gas fuel source that is conditioned, compressed to high pressure, dehydrated and transported in high pressure gas transport modules to the wellsites or facilities with mobile equipment operated by diesel engines. At the mobile equipment site, the transported gas is depressured and in the process hydrocarbon liquids are removed and the residual lean gas is fed through a Bi-Fuel delivery system to the diesel engine.
Embodiments of the present invention also provide a system and method for fueling mobile and transportable non-wellsite equipment, containing one or more diesel engines, with a mixture of natural gas and diesel fuel.
To achieve these and other advantages, in general, in one aspect, a method of capturing, transporting, processing, and utilizing stranded natural gas is provided. The method includes transporting a compressed natural gas that contains hydrocarbon liquids in vapor form captured from a natural gas producing well at a gas well location in pressure containers from the gas well location to a gas consuming location; and processing the compressed natural gas containing hydrocarbon liquids in vapor form at the gas consuming location to provide a compressed natural gas separate of the hydrocarbon liquids to a fuel system for consumption.
To achieve these and other advantages, in general, in one aspect, a method of capturing, transporting, processing, and utilizing stranded natural gas is provided. The method includes capturing a natural gas from a natural gas producing well at a gas well location to provide a raw natural gas; conditioning the raw natural gas to sweeten and dehydrate the raw natural gas to provide a sweet dry natural gas; compressing and cooling the dry natural gas to a pressure and temperature to provide a compressed natural gas containing hydrocarbon liquids in vapor form; transporting the compressed natural gas containing hydrocarbon liquids in vapor form in pressure containers from the gas well location to a gas consuming location; and processing the compressed natural gas containing hydrocarbon liquids in vapor form at the gas consuming location to provide a compressed natural gas separate of the hydrocarbon liquids to a fuel system for consumption.
In general, in another aspect, the processing step may further include feeding the compressed natural gas containing hydrocarbon liquids in vapor form as a first gas stream through a first heat exchanger that is operated at a temperature to drop the hydrocarbon liquids to provide a second gas stream including a mixture of gas and hydrocarbon liquids; feeding the second gas stream through a separator to separate the gas and hydrocarbon liquids from the second gas stream into a third gas stream and a hydrocarbon liquid stream; expanding the third gas stream to provide a fourth gas stream at a lower pressure and temperature than that of third gas stream; feeding the fourth gas stream through a second heat exchanger that is operated a temperature to sub-cool the fourth gas stream to further drop the hydrocarbon liquids to provide a fifth gas stream including a mixture of gas and hydrocarbon liquids; and feeding the fifth gas stream through a separator to separate the gas and hydrocarbon liquids from the fifth gas stream into a sixth gas stream and a hydrocarbon liquid stream.
In general, in another aspect, the processing step may further include passing the sixth gas stream through an aftercooler to produce a cold discharge gas stream and a hot discharge gas stream; feeding the cold discharge gas stream through the second heat exchanger as a working fluid to sub-cool the fourth gas stream; and recombining the cold discharge gas stream and the hot discharge gas stream after the cold discharge gas stream exits the second heat exchanger to provide a seventh gas stream.
In general, in another aspect, the processing step may further include optionally heating the seventh gas stream and regulating the pressure of the seventh gas stream to provide the seventh gas stream at a pressure for delivery to the fuel system.
To achieve the above and other advantages, in general, in one aspect a system of capturing stranded natural gas from a gas producing well at a gas well site, transporting the captured stranded natural gas from the gas well site to a gas consuming site, and processing and utilizing the stranded natural gas as a fuel source at the gas consuming site is provided. The system comprising includes at least one pressure container carried for transporting by a transporting vehicle. A raw gas production facility located at the gas well site, and including means to capture raw gas produced by the gas producing well, a means for conditioning the captured raw gas, a means for compressing and cooling the conditioned, captured raw gas to produce a compressed natural gas containing hydrocarbon liquids in vapor form, and means to load the compressed natural gas containing hydrocarbon liquids in vapor form into the at least one pressure container for transport to the gas consuming site. And a liquid recovery facility and natural gas consumption facility located at the gas consuming site, and including means to unload the compressed natural gas containing hydrocarbon liquids from the at least one pressure container, means to process the compressed natural gas containing hydrocarbon liquids in vapor form to provide a compressed natural gas separate of the hydrocarbon liquids to a fuel system for consumption, and means to consume the compressed natural gas.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood and in order that the present contribution to the art may be better appreciated.
Numerous objects, features and advantages of the present invention will be readily apparent to those of ordinary skill in the art upon a reading of the following detailed description of presently preferred, but nonetheless illustrative, embodiments of the present invention when taken in conjunction with the accompanying drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
For a better understanding of the invention, its operating advantages and the specific objects attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated embodiments of the invention.
The following drawings illustrate by way of example and are included to provide further understanding of the invention for the purpose of illustrative discussion of the embodiments of the invention. No attempt is made to show structural details of the embodiments in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. Identical reference numerals do not necessarily indicate an identical structure. Rather, the same reference numeral may be used to indicate a similar feature of a feature with similar functionality. In the drawings:
a is a schematic view of a system and method constructed in accordance with the principles of an embodiment of the present invention at a first wellsite or natural gas collection facility;
b is a schematic view of the system of
With reference now to
With particular reference to
If gas 16R is wet (includes liquids) and/or is sour or acidic (includes H2S or CO2) the gas 16R will have to be “Conditioned” to remove free liquids, sweeten the gas and dehydrate the gas to remove water to produce gas 16C. To condition gas 16R, the gas is fed initially through pressure regulator valve 60 and then to a liquid-gas separator 22, which functions to separate the gas from associated liquids, the latter being drained off through a discharge line 24 to a liquid storage vessel or elsewhere. Pressure regulator valve 60 functions to ensure gas 16R that is fed to liquid-gas separator 20 is at a safe and sufficient pressure sensed by controller 61 for the operation of the liquid-gas separator and the various other downstream components.
The outlet of the liquid-has separator 22 is fluidically connected to a sweetener 26, which functions to remove hydrogen sulfide (H2S) or carbon dioxide (CO2) from the gas 16R. The sweetener 26 is fluidically connected to a gas dehydrator 28, such as, but not limited to a Mole Sieve dryer, that functions to remove saturated water from gas 16R and rendering it sufficiently dry for further processing. A compressor 30 is connected to dehydrator 28, and operates to compress the sweet dry gas 16C that is discharged from the dehydrator 28 to a high pressure required to transport the gas as a compressed natural gas containing hydrocarbon liquids (CNG or Gas 16C). The compressed gas 16C is cooled by cooler 32 to a temperature that is maintained above a temperature and pressure where liquids would form so that only vaporized gas is discharged from the cooler and loaded on to the pressure containers 42 as CNG.
Should the raw gas 16R be at a pressure that is too low for the sweetener 26 and dehydrator 28 to operate properly an alternative arrangement of gas sweetening, dehydration and compression could be facilitated.
Gas pressure sensor and controller 34 monitors the pressure of gas 16C discharged from cooler 32, and if the measured pressure of gas 16C exceeds a predetermined pressure, such as, for example a pressure greater than a desired transport pressure or a pressure that is elevated above the pressure rating of any component downstream of valve 36, the gas is redirected through line 38 to the suction side of the last stage of compression in compressor 30. If after a predetermined period the measured pressure of gas 16C remains elevated from the predetermined pressure as sensed by gas pressure sensor 34, the system 10 enters a shutdown mode, and ESD valve 20 is closed and pressure relief 39 is vented to atmosphere to prevent damage to the system and injury to operators.
Otherwise, the cooled and compressed gas 16C is passed through valve 36 and regulator 37 into a manifold 40 as stream 69 for filling pressure containers 42 carried by a transport truck 44. Regulator 37 adjusts delivery pressure as required and limited by pressure containers 42. Manifold 40 may include one or more fill lines 46 that includes a fill valve 48, a bleed valve 50 and a suitable line connector 52. Gas loading valve 54 is fluidically connected to pressure containers 42. A suitable line connector 56 at loading valve 54 engages with line connector 52 at fill valve 48. Once pressure containers 42 are filled, valves 48 and 54 are closed, and bleed valve 50 is opened to vent the fill line 46 to atmosphere. Once vented, connectors 52 and 56 are disengaged, and the transport truck 44 leaves wellsite or facility 12.
If gas 16R is dry (free from liquids), sweet (does not include H2S or CO2), and at a high pressure, the gas is diverted through line 58 through the operation of controller 63 and valve 62, so that flow is facilitated from stream 64 to stream 66 and blocked from stream 65, thereby by-passing the separator 22, the sweetener 24, the dehydrator 28, the compressor 30 and the cooler 32, and flowing directly to and through valve 36 and regulator 37 into manifold 40. In addition, controller 57 and regulator valve 60 will be operated such that flow in line 59 is stopped.
Once the pressure containers 42 are loaded with CNG captured from source 14, the CNG is transported to a remote wellsite or facility by transport truck 44 for consumption at the remote wellsite or facility as a fuel source for mobile and transportable equipment. Of course, transport truck 44 could alternatively be a rail car, or other vehicle suitable for the transportation of pressure containers 42. Further yet, pressure containers 42 may not be directly transported from the collection wellsite or facility to a consumption wellsite or facility, and rather may be transported to a storage facility until a call or demand for gas 16C from a consumption wellsite or facility is received.
Now, with particular reference to
Conditioned and compressed natural gas 16C loaded into pressure containers 42 from wellsite or facility 12 are transported to wellsite or facility 100 by truck 44 for consumption at wellsite or facility 100 by the one or more gas users. System 10 at wellsite or facility 100 includes one or more unloading lines 104 connected to a manifold 109. Unloading lines 104 include a valve 106, a bleed valve 108 and a suitable line connector 110. Line connector 56 is engaged with line connector 110, and valves 54 and 106 are opened to permit a flow of the gas 16C from the pressure containers into manifold 109.
From manifold 109, gas 16C flows through a main ESD valve 112. If gas 16C is liquid rich it is fed through heat exchanger A 146, which is operated to lower the temperature of the gas to a desired temperature for drop out of hydrocarbon liquids. The cooled gas and liquid mixture in stream 115 is fed in to separator 118 to separate the gas from the liquids. The gas exiting the separator 118 as stream 117 is passed through a choke valve 116, where the high pressure gas is expanded and the pressure is reduced by flowing through a restriction in the choke valve. As the gas is expanded and depressurized, the gas is cooled through the Joule Thompson effect to a much lower temperature. This low temperature gas in stream 111 is passed through heat exchanger A 146 to cool the inlet gas 16C to a temperature so that a liquid/gas mixture is produced and sent as stream 115 to separator 118. During stabilized operation it will be readily apparent to those of ordinary skill in the art that the temperature in the gas and liquid stream 115 and the gas stream exiting heat exchanger A 146 as stream 112 will stabilize and approach a similar value.
The gas-liquid separator 118, functions to separate gas 117 from associated liquids 119, the latter being drained off through a discharge conduit 120 to a liquid storage vessel or elsewhere.
The cooled gas 16C exiting heat exchanger A 146 as stream 112 is fed to heat exchanger B 147 which is operated to further lower the temperature of the gas to a desired “sub-cooled” temperature for additional drop out of hydrocarbon liquids. The sub-cooled gas and liquid mixture in stream 113 is fed in to LTS separator 126 to separate the gas from the liquids. The gas exiting the separator 126 as stream 125 is passed through a Vortex after cooler 122, where the sub-cooled gas is separated in to two streams. The Vortex aftercooler 122 produces a cold discharge 121 (a discharge having a temperature lower than the temperature of the gas entering the vortex aftercooler) through line 124. The vortex aftercooler 112 also produces a hot discharge 123 (a discharge having a temperature higher than the temperature of the gas entering the vortex aftercooler) through line 128. This low temperature gas in stream 121 is used to cool the inlet gas 112 so that a liquid gas mixture is produced and sent as stream 113 to LTS separator 126. During stabilized operation it will be readily apparent to those of ordinary skill in the art that the temperature in the gas and liquid stream 113 and the gas stream exiting heat exchanger B 147 or stream 125 will stabilize and approach a similar value.
The LTS liquid-gas separator 126, functions to separate gas 125 from associated liquids 127, the latter being drained off through a discharge conduit 120 to a liquid storage vessel or elsewhere.
The gas exiting heat exchanger B 147 as stream 129 is fed through line 131 where it is combined with the hot discharge 123 from line 128 and the resultant dry gas flow 132 is fed thru an optional heater 114 that is used to heat the gas before it is depressured through pressure regulator 134. Pressure regulator 134 operates to reduce the pressure of gas stream 133 to a desired or suitable pressure for delivery to fuel system 102. From pressure regulator 134, gas 135 is delivered to one or more fuel systems 102 that are each connected to manifold 136 by feed lines 138. Feed line or feed lines 138 may include valve 140 to control the flow of gas 135 there through and to fuel system 102. Alternatively, and while not illustrated, feed line or feed lines 138 may include metering and a pressure regulator in addition to or in substitution of pressure regulator 134 as desired.
As gas 16C is unloaded from pressure containers 42, the pressure of the gas will begin to gradually lower as a result of being able to expand in the pressure containers. During unloading, gas 16C will reach a pressure that is too low to permit liquid separation and recovery, and will also reach a pressure that is suitable for direct feed to manifold 136 without regulation by pressure regulator 134. Once the pressure of gas 16C reaches this point, as sensed by controller 145, gas 16C is diverted through line 142 by the operation of valve 144, thereby bypassing each component downstream thereof and the pressure regulator 134, and is fed directly to manifold 136 as dry gas 16D.
If gas 16C is not liquid rich and is lean dry gas, the gas is fed through heat exchanger A 146 and the components downstream thereof as described above; however, there will be no liquids separated from the gas and liquid streams 119 and 127 will not be produced.
A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.
This application claims priority to U.S. provisional Patent Application No. 61/590,413 filed Jan. 25, 2012, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61590413 | Jan 2012 | US |
