Wellhead throttling system of remote gas well

Abstract

The invention provides a wellhead throttling system of a remote gas well, which belongs to the technical field of ground engineering energy conservation and comprises a front heating module, a rear heating module, a separation and filtration module, a turbine expansion module, a differential pressure power generation module, an automatic flow stabilization module and a pressure reduction gas supply module. Gas from a wellhead is preheated by the front heating module, then enters the rear heating module to be heated and then enters the separation and filtration module after being heated, one part of the filtered gas enters the automatic flow stabilization module, the other part of the filtered gas enters the turbine expansion module to be depressurized to do work and generate electricity, and generated electricity provides electric energy for the front heating module. The gas depressurized by the turbine expansion module is mixed with part of the gas depressurized and stabilized by the automatic flow stabilization module and then is output; and after being heated by the post-heating module, the residual gas subjected to pressure reduction and flow stabilization through the automatic flow stabilization module is subjected to secondary throttling and pressure reduction through a throttling valve to serve as fuel gas of the post-heating module, and circulation is conducted according to the steps. According to the system, energy supply in multiple forms of heat and electricity is achieved, and effective recycling of energy is guaranteed.

Description

Technical Field

[0001] The invention belongs to the technical field of ground engineering, and in particular relates to a wellhead throttling system for a remote gas well. Background Art

[0002] After being extracted from underground, natural gas from oilfield gas wells has a high pressure, usually between 10MPa and 40MPa. To ensure production safety, throttling and pressure reduction are required. However, the huge pressure difference energy generated by throttling is not fully utilized at present. The difficulty lies in: (1) the load fluctuation of natural gas flow is large and it is difficult to adapt to the general system; (2) expansion and pressure reduction will cause temperature drop, resulting in the back-end natural gas temperature being too low and causing freezing and blockage of the pipeline. Therefore, if appropriate residual energy utilization methods can be used to recover energy, a wellhead throttling process suitable for remote gas wells with reliable operation, automatic steady flow, and high power generation efficiency can be formed, which can recover wellhead pressure energy, reduce fuel gas consumption, and achieve energy saving and carbon reduction in gas well field gathering and transportation.

[0003] Chinese utility model patent CN202325702U discloses a natural gas pressure difference power generation system that is adaptive to rear-end load changes, which includes a natural gas pressure difference power generation system and a load automatic bypass pressure reduction and stabilization system. The natural gas pressure difference power generation system mainly includes: a single-stage or multi-stage centripetal turbine expander, a front-end preheater of the expander, an intermediate reheater between stages of the expander, a reducer, a generator set and other parts. The main feature of the system involved is that a set of load automatic bypass pressure reduction and stabilization system is set next to the natural gas pressure difference power generation system, and it runs simultaneously with the natural gas pressure difference power generation system. The load automatic bypass pressure reduction and stabilization system is used to adjust the amount of natural gas entering the rear-end pipeline network to solve the problem that the natural gas expansion unit is difficult to meet the load changes, and the stability and adaptability of the entire natural gas pressure difference power generation system are greatly improved. Furthermore, a pressure stabilizing valve can be added to the rear end of the natural gas pressure difference power generation system, and a natural gas pressure stabilizing tank can be added at the end of the system, so that the natural gas pressure of the rear-end pipeline network can be further stabilized, and the stability of the natural gas pressure difference power generation system can be improved again, and the adaptability of the natural gas pressure difference power generation system can be increased. However, the differential power generation system is only adapted to the operating conditions of rear-end load changes, and does not describe the scenarios of front-end load and pressure changes; and does not specifically describe the system voltage stabilization conditions. Summary of the invention

[0004] In view of the problems existing in the above-mentioned prior art, the present invention provides a wellhead throttling system for remote gas wells. The technical problem to be solved by the present invention is to provide a wellhead throttling system for remote gas wells that can utilize the pressure energy and adapt to changes in the front-end gas, thereby realizing energy utilization and recovery and improving the reliability and stability of the entire system.

[0005] In order to solve the above technical problems, the present invention provides a wellhead throttling system for remote gas wells, comprising a front heating module, a rear heating module, a separation and filtration module, a turbine expansion module, a differential pressure power generation module, an automatic flow stabilization module and a pressure reduction gas supply module;

[0006] The front heating module is connected to the wellhead outlet, the rear heating module, the separation and filtration module, the turbine expansion module and the differential pressure power generation module are sequentially connected in series behind the front heating module, the outlet of the differential pressure power generation module is connected to the front heating module, the pressure reduction and air supply module is connected in series with the rear heating module, and the automatic flow stabilization module is connected in parallel with the turbine expansion module;

[0007] The gas from the wellhead is first preheated by the front heating module, then enters the rear heating module for heating, and then enters the separation and filtration module. Part of the filtered gas enters the automatic flow stabilization module, and part enters the turbine expansion module to reduce the pressure and do work to generate electricity. The generated electricity provides power for the front heating module. The gas after reducing the pressure by the turbine expansion module is mixed with part of the gas after reducing the pressure and stabilizing the flow by the automatic flow stabilization module and then transmitted externally; the remaining part of the gas after reducing the pressure and stabilizing the flow by the automatic flow stabilization module is heated by the rear heating module and then throttled and reduced in pressure for the second time, and serves as the fuel gas for the rear heating module, and the cycle continues.

[0008] Further, the front heating module includes an electric heater.

[0009] Furthermore, the post-heating module includes a water bath heating furnace.

[0010] Furthermore, the separation and filtration module includes a filter.

[0011] Furthermore, the reduced pressure air supply module includes a throttle valve.

[0012] Furthermore, the automatic flow stabilization module includes a JT valve.

[0013] Furthermore, the system also includes an expander and a generator, the expander and the generator constitute a turbine expansion module, and the expander, the generator and the electric heater constitute a differential pressure power generation module; the expander and the generator are connected in series on the rear side of the filter, and the generator is connected to the electric heater.

[0014] The present invention provides a wellhead throttling system for remote gas wells, which is mainly used in natural gas throttling and gathering scenarios in remote well sites. Since remote gas wells have no electricity or heat, the transportation distance is long and the pressure drop is large, the front heating and rear heating modules of the present application can be used to heat the natural gas in the remote gas wells and transport it to the pipeline network to provide thermal energy to prevent the formation of hydrates. There is no need for reheating at the back end of the expander, thus achieving low carbon and environmental protection. At the same time, an automatic flow stabilization process is adopted to automatically adjust the amount of natural gas according to the pressure after the valve, thereby solving the problem of large fluctuations in the wellhead natural gas flow load and ensuring the smooth operation of the pressure difference power generation system.

[0015] The present invention adopts an electric-gas coupled circulation structure, and utilizes the heat energy converted by pressure difference power generation as the hot end of the energy utilization system, realizing energy supply in multiple forms of heat and electricity, and ensuring effective energy recovery and utilization; the front heating module heats the natural gas at the front end of the wellhead, which can avoid the formation of hydrates when the temperature is too low during the expansion process, and the rear end of the expander does not need reheating to meet the energy supply, which is high in energy and low in consumption, and ensures efficient recycling of natural gas; the front heating module preheats the natural gas to reduce the combustion and heating of the water bath heating furnace, which is green, low-carbon, energy-saving and environmentally friendly; the automatic flow stabilization module connected in parallel with the expander can automatically adjust the system imbalance caused by significant fluctuations in the incoming gas volume, adjust the upstream and downstream pressure differences, and ensure the smooth operation of the pressure difference power generation system.

[0016] Compared with the prior art, the present invention is different in that:

[0017] The present invention has a short process, requires less equipment, and does not require back-end reheating. The heat energy converted by pressure difference power generation and the water bath heating furnace can meet the system heat supply; the existing technology requires multi-stage preheating and reheating of natural gas after expansion and cooling, which requires more heating equipment, a long process, and high energy consumption;

[0018] The automatic flow stabilization module of the present invention can accurately control the natural gas flow load fluctuations upstream and downstream of the expander, thereby achieving pressure balance of the system when the incoming gas volume is different; the automatic bypass pressure reduction and stabilization system of the prior art has a control range including multiple stages of preheating and reheating equipment, and cannot accurately control the system imbalance caused by natural gas load fluctuations during the expansion process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of an embodiment of a wellhead throttling system for a remote gas well according to the present invention.

[0020] Figure 2 It is a schematic diagram of an embodiment of a wellhead throttling system for a remote gas well according to the present invention.

[0021] Among them, 1-front heating module; 2-rear heating module; 3-separation and filtration module; 4-turbine expansion module; 5-differential pressure power generation module; 6-pressure reduction air supply module; 7-automatic flow stabilization module; 11-electric heater; 21-water bath heating furnace; 31-filter; 41-expander; 42-generator; 61-throttle valve; 71-JT valve. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0025] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0026] In order to better understand the purpose, structure and function of the present invention, a wellhead throttling system for a remote gas well of the present invention is further described in detail below in conjunction with the accompanying drawings.

[0027] Embodiment 1:

[0028] like Figure 1 As shown, a wellhead throttling system for a remote gas well of the present invention comprises a front heating module 1, a rear heating module 2, a separation and filtration module 3, a turbine expansion module 4, a differential pressure power generation module 5, an automatic flow stabilization module 7 and a pressure reduction gas supply module 6;

[0029] The front heating module 1 is connected to the wellhead outlet, the rear heating module 2, the separation and filtration module 3, the turbine expansion module 4 and the differential pressure power generation module 5 are sequentially connected in series behind the front heating module 1, the outlet of the differential pressure power generation module 5 is connected to the front heating module 1, the pressure reduction and air supply module 6 is connected in series with the rear heating module 2, and the automatic flow stabilization module 7 is connected in parallel with the turbine expansion module 4;

[0030] The gas from the wellhead is first preheated by the front heating module 1, and then enters the rear heating module 2 for heating. After heating, it enters the separation and filtration module 3. Part of the filtered gas enters the automatic flow stabilization module 7, and part enters the turbine expansion module 4 to reduce the pressure and do work to generate electricity. The generated electricity provides electric energy for the front heating module 1. The gas after reducing the pressure by the turbine expansion module 4 is mixed with part of the gas that has been reduced in pressure and stabilized by the automatic flow stabilization module 7 and then transmitted to the outside; the remaining part of the gas that has been reduced in pressure and stabilized by the automatic flow stabilization module 7 is heated by the rear heating module 2 and then throttled and reduced in pressure for the second time, and serves as the fuel gas of the rear heating module 2, and the cycle continues.

[0031] Embodiment 2:

[0032] like Figure 2 As shown, a wellhead throttling system for a remote gas well of the present invention comprises a front heating module 1, a rear heating module 2, a separation and filtration module 3, a turbine expansion module 4, a differential pressure power generation module 5, an automatic flow stabilization module 7 and a pressure reduction gas supply module 6;

[0033] The front heating module 1 is connected to the wellhead outlet, the rear heating module 2, the separation and filtration module 3, the turbine expansion module 4 and the differential pressure power generation module 5 are sequentially connected in series behind the front heating module 1, the outlet of the differential pressure power generation module 5 is connected to the front heating module 1, the pressure reduction and air supply module 6 is connected in series with the rear heating module 2, and the automatic flow stabilization module 7 is connected in parallel with the turbine expansion module 4;

[0034] The gas from the wellhead is first preheated by the front heating module 1, and then enters the rear heating module 2 for heating. After heating, it enters the separation and filtration module 3. Part of the filtered gas enters the automatic flow stabilization module 7, and part enters the turbine expansion module 4 to reduce the pressure and do work to generate electricity. The generated electricity provides electric energy for the front heating module 1. The gas after reducing the pressure by the turbine expansion module 4 is mixed with part of the gas that has been reduced in pressure and stabilized by the automatic flow stabilization module 7 and then transmitted to the outside; the remaining part of the gas that has been reduced in pressure and stabilized by the automatic flow stabilization module 7 is heated by the rear heating module 2 and then throttled and reduced in pressure for the second time, and is used as the fuel gas of the rear heating module 2, which can meet the safety operation requirements, and the cycle continues.

[0035] The rear heating module 2 needs to provide part of the combustion heat from the outside to meet the temperature requirement for the formation of the external gas hydrate, that is, heating is necessary. The front heating module 1 is an electric heater and does not require gas supply.

[0036] The difference between this embodiment and the first embodiment is that:

[0037] The front heating module 1 includes an electric heater 11;

[0038] The post-heating module 2 includes a water bath heating furnace 21;

[0039] The separation and filtration module includes a filter 31;

[0040] The reduced pressure gas supply module 6 includes a throttle valve 61, which provides the water bath heating furnace 21 with fuel gas after secondary throttling and pressure reduction;

[0041] The automatic flow stabilization module 7 includes a JT valve 71;

[0042] The system also includes an expander 41 and a generator 42, which constitute a turbine expansion module 4. The expander 41, the generator 42 and the electric heater 11 constitute a differential pressure power generation module; the expander 41 and the generator 42 are connected in series in sequence on the rear side of the filter 31, and the generator 42 is connected to the electric heater 11.

[0043] The gas from the wellhead is first preheated by the electric heater 11, and then enters the water bath heating furnace 21 for heating. After heating, it enters the filter 31 for liquid removal, and a part of it enters the expander 41 for pressure reduction and work, driving the generator 42 to generate electricity. The generated electricity provides power for the electric heater 11. The reduced-pressure gas is mixed with a part of the gas that has passed through the JT valve 71 for pressure reduction and flow stabilization, and then transmitted to the outside; another part of the gas that has passed through the JT valve 71 for pressure reduction and flow stabilization is heated by the water bath heating furnace 21 and then throttled and reduced in pressure for the second time, and is used as the fuel gas for the water bath furnace, and the cycle continues.

[0044] Secondary throttling and pressure reduction refers to the natural gas that has been reduced in pressure for the first time by the JT valve 71. After being heated by the water bath heating furnace 21, it is throttled and reduced in pressure for the second time by the throttle valve 61, and then enters the water bath heating furnace for combustion and heating, mainly to provide external heat energy to the system.

[0045] The natural gas temperature and pressure data in this system refer to Table 1:

[0046] Table 1 Wellhead throttling system export natural gas data

[0047] Pressure(MPa) Temperature(℃) Wellhead Natural Gas 20 25 Electric heater outlet natural gas 20 39.2 Water bath heating furnace outlet natural gas 20 65.5 Expander export natural gas 10 22.8

[0048] Note: 1. The gas field production is 100,000 Nm at standard conditions (1 atm, 20°C) 3 / d, at which point the natural gas density is 0.79156 kg / m 3 ;

[0049] 2. The enthalpy value of natural gas at each state point is calculated based on relevant software.

[0050] In the system of the present invention, the wellhead natural gas will do work externally through the adiabatic expansion process in the expander. According to the isentropic process calculation, the natural gas pressure at the expander outlet can be obtained to be 10MPa and the temperature to be 23°C. Assuming that the efficiency of the expander is 75%, the output power of the expander is 24.7kW, and the electric heating power is 23.57kW. The system can operate normally, which is a fully achievable technical indicator.

[0051] Simple calculations show that 5×104 Nm 3 / d gas well, if the conventional throttling process is adopted and natural gas is used to provide combustion energy, the heating power of the water bath heating furnace is about 199.3kW, and the efficiency of the heating furnace is calculated as 80%, then the daily natural gas consumption is about 579Nm 3 The process uses steady-flow gas as the fuel gas for the water bath heating furnace, and consumes 538Nm of natural gas per day. 3 , which can effectively save 41Nm 3 Natural gas volume, the annual gas saving is 12300Nm 3 , saving 16.4t of standard coal annually, effectively reducing carbon dioxide emissions by 23,370kg, and saving 14,760 yuan annually.

[0052] Embodiment 3:

[0053] By using a wellhead throttling system for a remote gas well of the present invention, high-pressure natural gas (about 13 MPa, 22.5°C) is extracted from the wellhead of the gas well, preheated to 41°C by an electric heater 11, and then heated to 68°C by a water bath heating furnace 21, and then enters a filter 31 for liquid removal, and then enters an expander 41 for pressure reduction to 11.2 MPa, and the temperature drops to 23°C. The pressure energy is converted into kinetic energy and drives a generator 42 to generate electricity. The depressurized gas is mixed with a portion of the depressurized and stabilized gas and then transmitted externally.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A wellhead throttling system for a remote gas well, characterized in that: It includes a front heating module, a rear heating module, a separation and filtration module, a turbine expansion module, a differential pressure power generation module, an automatic flow stabilization module and a pressure reduction and air supply module; The front heating module is connected to the wellhead outlet, the rear heating module, the separation and filtration module, the turbine expansion module and the differential pressure power generation module are sequentially connected in series behind the front heating module, the outlet of the differential pressure power generation module is connected to the front heating module, the pressure reduction and air supply module is connected in series with the rear heating module, and the automatic flow stabilization module is connected in parallel with the turbine expansion module; The gas from the wellhead is first preheated by the front heating module, then enters the rear heating module for heating, and then enters the separation and filtration module. Part of the filtered gas enters the automatic flow stabilization module, and part enters the turbine expansion module to reduce the pressure and do work to generate electricity. The generated electricity provides power for the front heating module. The gas after reducing the pressure by the turbine expansion module is mixed with part of the gas after reducing the pressure and stabilizing the flow by the automatic flow stabilization module and then transmitted to the outside; the remaining part of the gas after reducing the pressure and stabilizing the flow by the automatic flow stabilization module is heated by the rear heating module, and then passes through the pressure reducing gas supply module for secondary throttling and pressure reduction, and serves as the fuel gas for the rear heating module, and the cycle continues.

2. The wellhead throttling system for remote gas wells according to claim 1, characterized in that: The front heating module includes an electric heater.

3. The wellhead throttling system for remote gas wells according to claim 2, characterized in that: The post-heating module includes a water bath heating furnace.

4. The wellhead throttling system for remote gas wells according to claim 3, characterized in that: The separation filtration module includes a filter.

5. The wellhead throttling system for remote gas wells according to claim 4, characterized in that: The reduced pressure air supply module includes a throttle valve.

6. The wellhead throttling system for remote gas wells according to claim 5, characterized in that: The automatic flow stabilization module includes a JT valve.

7. The wellhead throttling system for remote gas wells according to claim 6, characterized in that: The system also includes an expander and a generator, which constitute a turbine expansion module, and the expander, generator and electric heater constitute a differential pressure power generation module; the expander and generator are connected in series on the rear side of the filter, and the generator is connected to the electric heater.

Images