An ultra-high pressure natural gas production system and a production method

Abstract

This invention relates to the field of natural gas extraction technology, specifically disclosing an ultra-high pressure natural gas extraction system and method; it includes a throttling component located at the wellhead, a cyclone separator and dehydration system connected to the throttling component, a molecular sieve dehydration system connected to the cyclone separator and dehydration system, a high-pressure gas transmission pipeline connected to the molecular sieve dehydration system, and a desulfurization system and a long-distance transmission pipeline connected to the high-pressure gas transmission pipeline. This invention utilizes the pressure energy from ultra-high pressure natural gas extraction, converting it into electrical energy, enabling energy reuse and reducing production costs.

Description

Technical Field

[0001] This invention relates to the field of natural gas extraction technology, and more specifically, to an ultra-high pressure natural gas extraction system and extraction method. Background Technology

[0002] Oil and gas gathering and transportation is a crucial aspect of natural gas or oil resource extraction, encompassing a wider range of operations compared to routine exploration drilling. Natural gas gathering and transportation processes primarily serve three functions: first, transporting the gas-liquid mixture extracted from the gas field via pipelines to processing stations; second, transporting processed natural gas to storage sites; and third, delivering qualified natural gas to users for consumption.

[0003] In the existing oil and gas gathering and transportation natural gas extraction technology, most of them are medium-pressure extraction, generally below 8MPa, while above 10MPa is high-pressure extraction.

[0004] Medium-pressure extraction results in significant pressure energy loss in individual wells, while long-distance pipelines typically transport at pressures around 10 MPa. Furthermore, power consumption is required to boost the pressure of natural gas before it can be transported through long-distance pipelines, wasting the high-pressure energy of natural gas and increasing extraction costs. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an ultra-high pressure natural gas extraction system and extraction method;

[0006] The solution adopted by this invention to solve the technical problem is:

[0007] An ultra-high pressure natural gas extraction system includes a throttling component located at the wellhead, a cyclone separation and dehydration system connected to the throttling component, a molecular sieve dehydration system connected to the cyclone separation and dehydration system, a high-pressure gas transmission pipeline connected to the molecular sieve dehydration system, and a desulfurization system and a long-distance transmission pipeline connected to the high-pressure gas transmission pipeline.

[0008] In some possible implementations, the throttling assembly includes a primary throttling valve located at the wellhead, a primary filter connected to the primary throttling valve, a secondary throttling valve connected to the primary filter, and a secondary filter connected to the secondary throttling valve; the cyclone separation and dehydration system is connected to the secondary filters respectively.

[0009] In some possible implementations, the throttling assembly further includes a water-jacketed furnace for heating the secondary throttling valve.

[0010] In some possible implementations, the cyclone separation dewatering system includes a cyclone separator connected to the molecular sieve dewatering system, a ball valve installed inside the cyclone separator and located at the bottom, and a filter bag installed at the bottom outlet of the cyclone separator.

[0011] In some possible implementations, the molecular sieve dewatering system includes two sets of molecular sieves respectively connected to a cyclone separation dewatering system.

[0012] In some possible implementations, a wastewater tank connected to the cyclone separation and dewatering system is also included.

[0013] An extraction method based on the above-described ultra-high pressure natural gas extraction system specifically includes the following steps:

[0014] Natural gas with a pressure of 50-100MPa and a temperature of 80℃ or higher is depressurized to 40MPa after passing through the first-stage throttling valve, and then enters the second-stage throttling valve after passing through the first-stage filter.

[0015] After being depressurized to 25MPa by a two-stage throttling valve, it passes through a two-stage filter and enters the cyclone separation and dehydration system for gas-liquid separation, with the gas phase entering the molecular sieve dehydration system.

[0016] After entering the molecular sieve dehydration system, the gas phase undergoes further dehydration before being transported out through a high-pressure gas pipeline. The sulfur-containing natural gas enters the desulfurization system for desulfurization treatment, while the sulfur-free natural gas is transported through the high-pressure gas pipeline to the deep dehydration well site CNG mother and daughter station, ultra-high pressure gas distribution station, or differential pressure power generation system.

[0017] In some possible implementations, when the natural gas at the secondary throttling valve is 0°C, the water jacket boiler is turned on to heat the natural gas.

[0018] In some possible implementations, at the initial stage of mining, the ball valve is opened, and the water and sand separated by the cyclone separator enter the filter bag, through which the sand is filtered.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] This invention utilizes the pressure energy extracted from ultra-high-pressure natural gas to convert it into electrical energy, enabling energy reuse and reducing production costs. Attached Figure Description

[0021] Figure 1 This is a schematic diagram illustrating the working principle of the ultra-high pressure mining system in this invention. Detailed Implementation

[0022] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. The terms "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, "a" or "one," etc., do not indicate a quantity limitation, but rather indicate the existence of at least one. In the implementation of this application, "and / or" describes the association relationship of related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more. For example, multiple positioning posts refer to two or more positioning posts. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] The present invention will now be described in detail.

[0024] An ultra-high pressure natural gas extraction system includes a throttling component located at the wellhead, a cyclone separator and dehydration system connected to the throttling component, a molecular sieve dehydration system connected to the cyclone separator and dehydration system, a high-pressure gas transmission pipeline connected to the molecular sieve dehydration system, and a desulfurization system and a long-distance transmission pipeline connected to the high-pressure gas transmission pipeline.

[0025] It should be noted that the design pressure of this invention is 30 MPa, and the operating pressure for extraction is 25 MPa. Because natural gas is buried at great depths, the wellhead pressure after completion is generally above 50 MPa, and in some cases, it can reach over 100 MPa.

[0026] After passing through the throttling components, the extraction working pressure is 25 MPa. The collected natural gas enters the cyclone separator dehydration system for gas-water separation, and the separated water is discharged. The separated natural gas then enters the molecular sieve dehydration system for further dehydration. The molecular sieve dehydration system is designed to operate at 25 MPa. After secondary dehydration, the natural gas is transported out through a high-pressure gas pipeline. If the natural gas contains sulfur, it is transported to a desulfurization system for desulfurization treatment. If it does not contain sulfur, it can be transported to a deep dehydration well site CNG mother-daughter station, an ultra-high pressure gas distribution station, or a differential pressure power generation system. This allows the natural gas to generate electricity through the differential pressure power generation system and supply it to industrial users or city gas, or to be centrally distributed through the ultra-high pressure gas distribution station to produce LNG, greatly saving electricity and reducing production and processing costs. Alternatively, CNG can be obtained through deep dehydration treatment at the deep dehydration well site CNG mother-daughter station and sold directly.

[0027] In some possible implementations, the throttling assembly includes a primary throttling valve located at the wellhead, a primary filter connected to the primary throttling valve, a secondary throttling valve connected to the primary filter, and a secondary filter connected to the secondary throttling valve; the cyclone separation and dehydration system is connected to the secondary filters respectively.

[0028] After passing through the first-stage throttle valve, the natural gas enters the first-stage filter for filtration. The pressure of the filtered natural gas is 40MPa. Then, it passes through the second-stage throttle valve and the second-stage filter in sequence. After the second filtration, the pressure of the gas in the vent is 25MPa. It then enters the cyclone separator dehydration system for gas-liquid separation, and then enters the molecular sieve dehydration system for further dehydration.

[0029] In some possible implementations, the throttling assembly further includes a water-jacketed furnace for heating the secondary throttling valve;

[0030] The water jacket furnace is used to heat low-temperature natural gas. When the temperature of the natural gas in the secondary throttling valve is detected to be 0°C, the water jacket furnace opens to heat the secondary throttling valve, thereby heating the natural gas.

[0031] In some possible implementations, the cyclone separation dewatering system includes a cyclone separator connected to the molecular sieve dewatering system, a ball valve installed inside the cyclone separator and located at the bottom, and a filter bag installed at the bottom outlet of the cyclone separator.

[0032] Natural gas, after passing through a secondary filter, enters a cyclone separator. Under the centrifugal force of the cyclone separator, gas and water are separated. The separated water will pass through a ball valve and then enter a filter bag, which will filter out the sand in the water. The filtered water will then be discharged.

[0033] When the sand content is low, filter bags are not required, and the separated water can be discharged directly.

[0034] Furthermore, in order to effectively store and centrally discharge the filtered water, a wastewater tank is installed at the bottom of the cyclone separation and dewatering system for water collection, storage and discharge.

[0035] In some possible implementations, the molecular sieve dehydration system includes two sets of molecular sieves respectively connected to the cyclone separator dehydration system; the two sets of molecular sieves can be used independently to form a switching system, which can always dehydrate the natural gas separated by the cyclone separator.

[0036] An extraction method based on the above-described ultra-high pressure natural gas extraction system specifically includes the following steps:

[0037] Natural gas with a pressure of 50-100MPa and a temperature of 80℃ or higher is depressurized to 40MPa after passing through the first-stage throttling valve, and then enters the second-stage throttling valve after passing through the first-stage filter.

[0038] After being depressurized to 25MPa by a two-stage throttling valve, it passes through a two-stage filter and enters the cyclone separation and dehydration system for gas-liquid separation, with the gas phase entering the molecular sieve dehydration system.

[0039] After entering the molecular sieve dehydration system, the gas phase undergoes further dehydration before being transported out through a high-pressure gas pipeline. The sulfur-containing natural gas enters the desulfurization system for desulfurization treatment, while the sulfur-free natural gas is transported through the high-pressure gas pipeline to the deep dehydration well site CNG mother and daughter station, ultra-high pressure gas distribution station, or differential pressure power generation system.

[0040] In some possible implementations, when the natural gas at the secondary throttling valve is 0°C, the water jacket boiler is turned on to heat the natural gas.

[0041] In some possible implementations, at the initial stage of mining, the ball valve is opened, and the water and sand separated by the cyclone separator enter the filter bag, through which the sand is filtered.

[0042] Ultra-high pressure natural gas extraction technology makes full use of wellhead pressure energy and employs a step-by-step energy utilization technology. It mainly improves energy utilization solutions based on the specific local conditions of the well, providing CNG refueling solutions; LNG production solutions; pressure energy differential pressure power generation solutions; and solutions for non-pressurized entry into long-distance pipelines for external transmission.

[0043] This invention employs ultra-high pressure extraction. After completion of a single gas well, the wellhead pressure is generally around 50 to 100 MPa, and the well temperature is above 80 degrees Celsius. Natural gas at 40 MPa, supplied from the first-stage throttling valve at the wellhead, passes through a first-stage filter, a second-stage throttling valve, and a second-stage filter. At a design pressure of 30 MPa and an operating extraction pressure of 25 MPa, the natural gas enters a cyclone separator / dehydration system for gas-liquid separation. After processing by the cyclone separator / dehydration system, the natural gas then enters a switching system with a design pressure of 25 MPa and a molecular sieve for further dehydration. Finally, it is transported out through a high-pressure gas pipeline.

[0044] Because the dehydration pressure drop in the cyclone separator is relatively small after passing through the two-stage throttling valve, it cannot form low-temperature hydrates. Therefore, a water jacket furnace can be omitted, and the water can directly enter the cyclone separator. After dehydration by molecular sieves, it is transported out under high pressure. The bottom of the cyclone separator is equipped with filter bags for sand removal and dehydration. Once mining is normal, the filter bags can be removed. The liquid is automatically discharged and transported to a 50 cubic meter wastewater tank for storage and transportation.

[0045] This invention is applicable to the following scenarios for sulfur-free natural gas:

[0046] Natural gas transported through high-pressure gas pipelines can be used for ultrasonic dehydration, and after differential pressure power generation, it enters long-distance pipelines.

[0047] Alternatively, after centralized processing at ultra-high pressure gas distribution stations, deep dehydration, sulfur removal, and CO2 removal can be achieved using an in-expander refrigeration process with an expansion ratio of 6:1. The temperature can be reduced to -120℃, and after throttling with a JT valve, the temperature can be reduced to below -150℃ to produce LNG at -162℃, significantly saving electricity. Each cubic meter of natural gas can reduce the external refrigerant circulation pressurization electricity cost by 0.3 kWh, thus lowering production and processing costs.

[0048] Of course, it can also be deeply dehydrated through ultra-high pressure natural gas molecular sieve, and the pressure energy can be used for ice making through frequency transmission. After differential pressure power generation, it can be supplied to industrial users or city gas.

[0049] After being transported from the well site to the gas gathering station via high-pressure pipelines and deeply dehydrated by molecular sieves, the gas is sold directly at CNG prices, increasing the selling price of natural gas by more than 1 yuan per standard cubic meter and increasing the company's profits.

[0050] For the desulfurization system of sulfur-containing natural gas being transported to the purification plant, except for the desulfurization tower, solution pump, and purified gas dehydration tower which are equipped with ultra-high equipment, the other equipment and process configurations remain basically unchanged and are adjusted based on the design parameters of the site.

[0051] This invention is not limited to the specific embodiments described above. The invention extends to any new feature or combination disclosed in this specification, as well as any new method or process step or combination disclosed herein.

Claims

1. An ultra-high pressure natural gas production system, characterized by, It includes a throttling assembly located at the wellhead, a cyclone separation and dehydration system connected to the throttling assembly, a molecular sieve dehydration system connected to the cyclone separation and dehydration system, a high-pressure gas transmission pipeline connected to the molecular sieve dehydration system, and a desulfurization system and long-distance transmission pipeline connected to the high-pressure gas transmission pipeline.

2. The ultra-high pressure natural gas extraction system according to claim 1, characterized in that, The throttling assembly includes a primary throttling valve located at the wellhead, a primary filter connected to the primary throttling valve, a secondary throttling valve connected to the primary filter, and a secondary filter connected to the secondary throttling valve; the cyclone separation and dehydration system is connected to the secondary filter.

3. The ultra-high pressure natural gas extraction system according to claim 2, characterized in that, The throttling assembly also includes a water jacket furnace for heating the secondary throttling valve.

4. The ultra-high pressure natural gas extraction system according to claim 1, characterized in that, The cyclone separation and dewatering system includes a cyclone separator connected to the molecular sieve dewatering system, a ball valve installed inside the cyclone separator and located at the bottom, and a filter bag installed at the bottom outlet of the cyclone separator.

5. The ultra-high pressure natural gas extraction system according to claim 4, characterized in that, The molecular sieve dewatering system includes two sets of molecular sieves that are respectively connected to the cyclone separation dewatering system.

6. The ultra-high pressure natural gas extraction system according to claim 4, characterized in that, It also includes a wastewater tank connected to the cyclone separation and dewatering system.

7. A method for extracting ultra-high pressure natural gas using a system according to any one of claims 1-6, characterized in that, Specifically, the following steps are included: Natural gas with a pressure of 50-100MPa and a temperature of 80℃ or higher is depressurized to 40MPa after passing through the first-stage throttling valve, and then enters the second-stage throttling valve after passing through the first-stage filter. After being depressurized to 25MPa by a two-stage throttling valve, it passes through a two-stage filter and enters the cyclone separation and dehydration system for gas-liquid separation, with the gas phase entering the molecular sieve dehydration system. After entering the molecular sieve dehydration system, the gas phase undergoes further dehydration before being transported out through a high-pressure gas pipeline. The sulfur-containing natural gas enters the desulfurization system for desulfurization treatment, while the sulfur-free natural gas is transported through the high-pressure gas pipeline to the deep dehydration well site CNG mother and daughter station, ultra-high pressure gas distribution station, or differential pressure power generation system.

8. The ultra-high pressure natural gas extraction system and extraction method according to claim 7, characterized in that, When the natural gas temperature at the secondary throttling valve is 0°C, the water jacket boiler is turned on to heat the natural gas.

9. The extraction method of an ultra-high pressure natural gas extraction system according to claim 7, characterized in that, In the initial stage of mining, the ball valve is opened, and the water and sand separated by the cyclone separator will enter the filter bag, through which the sand is filtered.

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