1. Field
This disclosure relates to burners and more particularly to oil and gas burners that may be used in the oil field industry.
2. Description of the Related Art
Hydrocarbons are widely used as a primary source of energy, and have a great impact on the world economy. Consequently, the discovery and efficient production of hydrocarbon resources is increasingly noteworthy. As relatively accessible hydrocarbon deposits are depleted, hydrocarbon prospecting and production has expanded to new regions that may be more difficult to reach and/or may pose new technological challenges. During typical operations, a borehole is drilled into the earth, whether on land or below the sea, to reach a reservoir containing hydrocarbons. Such hydrocarbons are typically in the form of oil, gas, or mixtures thereof which may then be brought to the surface through the borehole.
Well testing is often performed to help evaluate the possible production value of a reservoir. During well testing, a test well is drilled to produce a test flow of fluid from the reservoir. During the test flow, parameters such as fluid pressure and fluid flow rate are monitored over a period of time. The response of those parameters may be determined during various types of well tests, such as pressure drawdown, interference, reservoir limit tests, and other tests generally known by those skilled in the art. The data collected during well testing may be used to assess the economic viability of the reservoir. The costs associated with performing the testing operations may be substantial, however, and therefore testing operations should be performed as efficiently and economically as possible.
Fluids produced from the test well are generally considered to be waste and therefore are typically disposed of by burning, which raises environmental and safety concerns. Conventionally, the fluids are separated into gas and liquids inside a separator vessel, then burned using one of three types of burners: 1) an oil burner for liquid phase that will mix crude oil and air for a good combustion, 2) a gas flare that will directly burn the dry gas, and 3) a multiphase burner that can burn both phases simultaneously within certain limits.
Burners are designed to combust waste effluent at a maximum flow rate which corresponds to its burning capacity. The waste effluent also typically should be provided at a much lower flow rate to test the well under any conditions. A burner's operational range of flow rates is called a turndown ratio, which is defined as a ratio of its maximum flow rate capacity to its minimum flow rate capacity. Burners typically do not exceed a turndown ratio of 5. If the flow rate of waste effluent were decreased below that limit, the combustion would no longer be acceptable. When the waste effluent flow rate drops below the minimum flow rate, a condition known as “fall out” may occur during which the hydrocarbon-containing waste effluent is not combusted but instead is discharged into the surrounding environment.
Well testing implies very large variations of flow rates because wells can be very different from one another. The well test burner should be adapted to that large range of flow rates during well testing, but is limited by its turndown ratio. To account for large fluctuations in effluent flow rates, the current practice is to provide at the well test site a set of separate burners having different sizes and burning capacities. For example, gas flares having various diameters may be located at the well test site in anticipation and preparation of large waste gas effluent flow rate fluctuations. Another example is an oil burner composed of a set of identical nozzles, where several nozzles can be replaced by plugs in order to reduce the flow rate characteristics of the burner. Based on the estimated maximum and minimum waste effluent flow rates, which may be difficult to predict, the operator will then select and assemble the most appropriate burner before beginning the well test in order to optimize the combustion and withstand the maximum and minimum forecasted flow rates.
In those situations, the well test operator will select the appropriate burner according to the estimated maximum and/or minimum flow rate of the specific well subjected to a well test. During a well test, however, flow rates may greatly vary, so there will be some phases with low flow rates with non-optimized combustion or even no combustion, which is also environmentally unfriendly and potentially hazardous to the operators. When those situations arise, the operators shut down the well test, wait for associated equipment to cool off, modify the burner currently used to account for the changing flow rates or even exchange the burner currently used with a different burner altogether that is more suitable to the current flow rate from the well. After the operators have modified or replaced the burner, they then restart the well test. These interruptions may result in lengthy delays lasting several hours to even days.
Certain aspects of some embodiments disclosed herein are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the embodiments might take and that these aspects are not intended to limit the scope of the disclosure. Indeed, the disclosure may encompass a variety of aspects that may not be set forth below.
In some embodiments, a burner apparatus includes a manifold assembly having an inlet, a first outlet, a second outlet, and a first control valve movable between a first and second position. The burner apparatus also includes a first burner head assembly fluidly communicating with the first outlet and a second burner head assembly fluidly communicating with the second outlet. The first control valve is selectively controllable to direct a combustible mixture to the first burner head assembly when in the first position and to the first and second burner head assembly when in the second position.
In some embodiments, a system for burning waste effluent containing hydrocarbons includes a waste effluent conduit fluidly communicating with a source of waste effluent and a manifold assembly fluidly communicating with the waste effluent conduit. The manifold assembly includes an inlet, a first outlet, a second outlet, and a first control valve movable between a first and a second position. The system also includes a pilot configured to generate a pilot flame, a first burner head assembly fluidly communicating with the first outlet, and a second burner head assembly fluidly communicating with the second outlet. The first control valve is selectively controllable to direct the waste effluent to the first burner head assembly when the first control valve is in the first position and to the first and second burner head assembly when the first control valve is in a second position.
In some embodiments, a method for burning a waste effluent containing hydrocarbons produced from a well during a well test includes starting a well test, producing a waste effluent containing hydrocarbons from the well at an initial flow rate, and directing the waste effluent to a burner apparatus. The burner apparatus includes a manifold assembly housing a first control valve movable between a first and a second position and a first and second burner head assembly fluidly communicating with the manifold assembly. The first control valve is selectively controllable to direct the waste effluent to the first burner head assembly when the first control valve is in the first position and to the first and second burner head assembly when the first control valve is in the second position. The method also includes burning the waste effluent with the first burner head assembly when the first control valve is in the first position and monitoring the flow rate of the waste effluent produced from the well to determine if the waste effluent flow rate will surpass a burning capacity of the first burner head assembly. The method further includes burning the waste effluent with both the first and second burner head assembly when the flow rate surpasses the burning capacity of the first burner head assembly without stopping production of the waste effluent from the well.
So that the manner in which the above recited features can be understood in detail, a more particular understanding may be had when the following detailed description is read with reference to certain embodiments, some of which are illustrated in the appended drawings in which like characters represent like parts throughout the drawings. It is to be noted, however, that the appended drawings illustrate only some embodiments and are therefore not to be considered limiting of its scope, and may admit to other equally effective embodiments.
Methods and apparatus are disclosed herein for combusting waste effluent generated by well testing, oil spill cleanup, or other operations. The term “waste effluent” is intended to encompass any fluid having a hydrocarbon content capable of being disposed of by combustion. The waste effluent may include a liquid hydrocarbon content (such as oil), a gas hydrocarbon content (such as methane), and non-hydrocarbon containing content (such as seawater), thus forming a combustible mixture. Other fluids and solids may also potentially be part of the waste effluent, some of which will be separated from the waste effluent in a separator tank before combusting the waste effluent. Still, the waste effluent sent to the burner apparatus for combustion may include some of the other fluids and solids. The waste effluent may be obtained from effluent from a supply line formed during well testing operations, oil-water mixtures created during an oil spill cleanup, or other sources.
The burner apparatus 20 includes a manifold assembly 30 for directing the waste effluent to one or more burner head assemblies 42, 44 in fluid communication with the manifold assembly 30. The burner head assemblies 42, 44 may discharge the waste effluent in a pattern suitable for combustion by open flame. The manifold assembly 30 has a first inlet 31 and multiple outlets 32, 34, 36. The first inlet 31 fluidly communicates with the main burner pipe 26 for directing the waste effluent to the manifold assembly 30 and to a first control valve 35 housed within the manifold assembly 30. The first control valve 35 is movable between a first position and a second position, as will be shown and described in more detail in
The burner apparatus 20 provides burner head assemblies 42, 44 that share the same inlet 31 via a manifold assembly 30 having one or several control valves to select the burner assembly to be used during the burning operation. The control valve(s) may be remotely controlled with an electric, pneumatic, or hydraulic control system. By selecting different sizes of burner assemblies, the result is a wide-range burning capacity combustion system that can ensure good burning regardless of fluctuations in flow rates, thereby preventing fall out or other environmental concerns when combusting waste effluent when performing a well test.
The first control valve 35 is selectively controllable to direct the waste effluent, a combustible mixture, to the first burner head assembly 42 when the control valve 35 is in the first position and to the first and second burner head assemblies 42, 44 when it is in the second position as will be shown in more detail in
Turning to
In some embodiments, the first control valve 335 is a piston 333 housed within a manifold assembly 330. The piston 333 together with the manifold assembly 330 form a first chamber 338 and a second chamber 339 within the manifold assembly 330. A piston control system 700 as shown in
The piston 333 is movable and selectively controllable between a first (closed) position 350 and a second (open) position 450, such that when the piston 333 is in the first position 350 as shown in
A pressure regulator 780, a check valve 785, and a pressure gauge 790 may be positioned along the second inlet line 762 such that constant pressure is provided to the second chamber 339 causing the piston 333 to be in the second position 450 by default. The pressure regulator 780 may generate a permanent intermediate pressure in the second chamber 339. The pressure regulator 780 can be set to deliver half of the inlet pressure so that it maintains a P/2 at any time in the second chamber 339. That pressure can push the piston to the open position (towards the left as shown in
In another embodiment, the piston control system may simply be two pressurized fluid supply lines directly to the first and second chambers 338, 339 as shown in
The piston 333 may slide between open and closed positions using a moderate pressure differential, such as a few bars. That pressure can be provided by a pressurized fluid, such as oil or water, or compressed air or nitrogen. Nitrogen may be a beneficial choice as it increases the safety of the burning apparatus should a leak occur as nitrogen is not combustible unlike oxygen. Some benefits the piston control system 700 may provide include use of one pressurized fluid inlet, thereby decreasing the cost of pressurized fluids involved for operating the burning apparatus and a simplified control panel and piping. Other benefits may include that some pressure trapped into the second chamber 339 will act as a spring to make a fail-safe system. In the absence of any operator or controller commands, the piston will remain open to both burner head assemblies, allowing any flow rate for safety. The system shown also allows low flow rate combustion through the central burner 342 alone and high flow rate combustion through both burners when the piston 333 opens the annular path 337. The burner apparatus may have a turndown ratio greater than 10 and as high as 20, or anywhere between those ranges.
Turning to
In view of the foregoing, systems and methods are provided for burning waste effluent containing hydrocarbons, such as a waste effluent produced from a well during a well test. The method includes initiating a well test by the operators, producing a waste effluent containing hydrocarbons from the well at an initial flow rate, and directing the waste effluent to a burner apparatus. The burner apparatus includes a manifold assembly housing a first control valve movable between a first and second position and a first burner head assembly and a second burner head assembly fluidly communicating with the manifold assembly. The first control valve is selectively controllable to direct the waste effluent to the first burner head assembly when the first control valve is in the first position and to the first and second burner head assemblies when the first control valve is in the second position.
The method also includes burning the waste effluent with the first burner head assembly when the first control valve is in the first position. Further, the method includes monitoring the flow rate of the waste effluent produced from the well to determine if the waste effluent flow rate will surpass a burning capacity of the first burner head assembly. If the flow rate does surpass the burning capacity of the first burner head assembly, the operators burn the waste effluent with both the first and second burner head assemblies without stopping production of the waste effluent from the well. The operators may accomplish this by moving the first control valve to the second position while waste effluent flow continues unabated.
The method may also include monitoring the flow rate of the waste effluent to determine if the flow rate will be greater than the burning capacity of the first burner head assembly but smaller than a burning capacity of the second burner head assembly. If the operators observe that the flow rate surpasses the burning capacity of the first burner head assembly but not the second burner head assembly, then the waste effluent may be burned solely with the second burner head assembly without stopping production of the waste effluent from the well. This may be accomplished by moving a second control valve housed in the manifold assembly to a closed position, such that when the first control valve is in the second position and the second control valve is in the closed position, the second control valve blocks the combustible mixture from flowing through the first outlet to the first burner head assembly.
As shown and described herein, some embodiments of the disclosure include a system for burning waste effluent containing hydrocarbons. The system includes a waste effluent conduit 26 fluidly communicating with a source of waste effluent 25 and a manifold assembly 30 fluidly communicating with the waste effluent conduit 26. The manifold assembly 30 has an inlet 31, a first outlet 32, a second outlet 34, and a first control valve 35. A pilot 345 is configured to generate a pilot flame to ignite the waste effluent. A first burner head assembly 42 fluidly communicates with the first outlet 32, and a second burner head assembly 44 fluidly communicates with the second outlet 34. The first control valve 35 is selectively controllable to direct the waste effluent to the first burner head assembly 42 when in a first position and to the first and second burner head assemblies 42, 44 when in a second position.
In some embodiments the system for burning was effluent includes a piston control system 700 and the first valve 35 may be formed as a piston 333 disposed within a manifold assembly 340. The piston control system 700 may be used to selectively control the piston 333. The piston 333 together with the manifold assembly 330 form a first chamber 338 and a second chamber 339 within the manifold assembly 330. The manifold assembly 330 forms an annular path 337 around the central burner 342 that fluidly communicates with a second outlet 334 and a third outlet 336.
Some embodiments of the system for burning waste effluent may include a second control valve 335 housed within the burning apparatus 520. The second control valve 335 has an open and a closed position such that when the first control valve 335 is in the second position and the second control valve 535 is in the closed position (
Some embodiments of the system for burning waste effluent may also include a piston control system 700 that has a pressurized fluid supply line 760 for supplying pressurized fluid to the system 700. A first inlet line 761 fluidly communicates with the first chamber 338 and the pressurized fluid supply line 760. Similarly, a second inlet line 762 fluidly communicates with the second chamber 339 and the pressurized fluid supply line 760. The first inlet line 761 supplies pressurized fluid 738 to the first chamber 338 and the second inlet line 762 supplies pressurized fluid 739 to the second chamber 339. Thus, the piston control system 700 also includes pressurized fluid in the first and second chambers 338, 339. A pressure regulator 780, a check valve 785, and a pressure gauge 790 may be positioned along the second inlet line 762 such that constant pressure is provided to the second chamber 339 causing the piston 333 to be in the second position by default. The pressure regulator 780 may generate a permanent intermediate pressure in the second chamber 339.
Although the preceding description has been described herein with reference to particular means, materials and embodiments, it is not intended to be limited to the particulars disclosed herein; rather, it extends to all functionally equivalent structures, methods, and uses, such as are within the scope of the appended claims.
Number | Date | Country | Kind |
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14290392.1 | Dec 2014 | EP | regional |