CN1920251B - Method and device for natural gas hydrate exploitation with in-situ catalytic oxidation thermochemistry method - Google Patents

Abstract

Translated fromChinese

本发明提供了一种原位催化氧化热化学法开采天然气水合物的方法及装置。方法特征为：向水合物储层注入水合物分解促进剂分解天然气水合物；同时在安装于开采井下的催化氧化燃烧器中采用氧化剂原位催化氧化燃烧燃料加热载热流体，然后将载热流体泵入水合物储层供给天然气水合物分解所需的热能；将催化氧化燃烧所产生的CO₂气体注入水合物储层。装置包括催化氧化燃烧器14，为一同轴套管反应器，管程为催化氧化燃烧区，壳程分为预热段和换热段。本发明解决了传统热激发法热量损失大，开采效率低的缺点，采用化学法和CO₂置换相结合，加快了开采速率、大大降低化学注剂的用量，同时有效地保证了海底地质的稳定，避免了地质及环境灾害的发生。

The invention provides a method and a device for exploiting natural gas hydrate by an in-situ catalytic oxidation thermochemical method. The characteristics of the method are: injecting a hydrate decomposition accelerator into the hydrate reservoir to decompose the natural gas hydrate; at the same time, in the catalytic oxidation burner installed in the production well, in-situ catalytic oxidation combustion fuel is used to heat the heat-carrying fluid with an oxidant, and then the heat-carrying fluid is Pump into the hydrate reservoir to supply the thermal energy required for the decomposition of natural gas hydrate; inject the CO₂ gas produced by catalytic oxidation combustion into the hydrate reservoir. The device includes a catalytic oxidation burner 14, which is a coaxial casing reactor, the tube side is a catalytic oxidation combustion zone, and the shell side is divided into a preheating section and a heat exchange section. The invention solves the disadvantages of large heat loss and low mining efficiency of the traditional thermal activation method, adopts the combination of chemical method and_CO2 replacement, accelerates the mining rate, greatly reduces the amount of chemical injection, and effectively ensures the stability of seabed geology , to avoid the occurrence of geological and environmental disasters.

Description

Translated fromChinese

一种原位催化氧化热化学法开采天然气水合物的方法及装置A method and device for exploiting natural gas hydrate by in-situ catalytic oxidation thermochemical method

技术领域technical field

本发明涉及天然气水合物的开采技术，尤其是一种原位催化氧化热化学法开采天然气水合物的方法及装置。The invention relates to the exploitation technology of natural gas hydrate, in particular to a method and a device for exploiting natural gas hydrate by an in-situ catalytic oxidation thermochemical method.

技术背景technical background

天然气水合物(Natural Gas Hydrate，简称Gas Hydrate)是在低温、高压条件下水和天然气中低分子量的烃类化合物形成的一种非化学计量型、类冰状、笼型结晶化合物。天然气水合物具有主-客体材料特征，水分子(主体)通过氢键结合形成空间点阵结构，气体分子(客体)通过与水分子之间的范德华力填充于水分子点阵间的空穴中。自然界存在的天然气水合物以甲烷水合物为主，其中绝大部分赋存于海底，具有储量大、分布广、埋藏浅、能量密度高、燃烧后无污染和残留等优点。单位体积的甲烷水合物分解可产生150-180标准体积的甲烷气体。海底及陆地永冻土层下存在着广泛的天然气水合物形成条件，据估计，地球上以天然气水合物形式储藏的有机碳占全球总有机碳的53％，是煤、石油、天然气三种化石燃料总碳量的2倍。因此，天然气水合物被认为是21世纪的理想清洁替代能源。Natural Gas Hydrate (Natural Gas Hydrate, referred to as Gas Hydrate) is a non-stoichiometric, ice-like, cage-type crystalline compound formed from low-molecular-weight hydrocarbons in water and natural gas under low temperature and high pressure conditions. Natural gas hydrate has the characteristics of a host-guest material. Water molecules (host) form a spatial lattice structure through hydrogen bonding, and gas molecules (guests) fill the cavities between the water molecule lattices through van der Waals forces with water molecules. . Natural gas hydrates are mainly methane hydrates, most of which occur in the seabed, which have the advantages of large reserves, wide distribution, shallow burial, high energy density, and no pollution and residue after combustion. The decomposition of methane hydrate per unit volume can produce 150-180 standard volumes of methane gas. There are extensive natural gas hydrate formation conditions under the seabed and land permafrost. It is estimated that the organic carbon stored in the form of natural gas hydrate on the earth accounts for 53% of the world's total organic carbon, which is the three fossils of coal, oil and natural gas. 2 times the total carbon content of the fuel. Therefore, natural gas hydrate is considered to be an ideal clean alternative energy source in the 21st century.

天然气水合物以固体形式赋存于泥质海底的松散沉积层中，在开采过程中发生相转化，与石油、天然气的开采相比，具有很大的开采难度。天然气水合物，特别是海洋天然气水合物的开采尚处于实验探索阶段，迄今为止，人们尚未找到技术上可行，经济上合理的海洋天然气水合物的开采方法。根据开采过程中水合物分解的地点不同，天然气水合物的开采可分为地下开采和地上开采两大类。其中地下开采研究报道最多，主要是参考石油、天然气的开采工艺，首先在海底地层中构筑井筒，采取措施破坏水合物稳定存在的温度、压力等热力学条件，促进水合物在赋存地分解为水和天然气，然后采用天然气开采工艺将分解后的天然气收集、输送至地面。天然气水合物地下开采的关键是如何采取经济有效的措施促进水合物的分解，同时保持井底稳定，不使甲烷泄漏、不引发温室效应。目前提出的方法主要包括热激发法、降压法和化学法三种。Natural gas hydrate exists in the loose sedimentary layer of the muddy seabed in solid form, and undergoes phase transformation during the exploitation process. Compared with the exploitation of oil and natural gas, it is very difficult to exploit. The exploitation of natural gas hydrate, especially marine natural gas hydrate is still in the stage of experimental exploration, so far, people have not found a technically feasible and economically reasonable marine natural gas hydrate exploitation method. According to the location of hydrate decomposition during the mining process, the mining of natural gas hydrate can be divided into two categories: underground mining and above-ground mining. Among them, underground mining research reports are the most, mainly referring to the oil and natural gas mining technology. Firstly, a wellbore is constructed in the seabed strata, and measures are taken to destroy the thermodynamic conditions such as temperature and pressure for the stable existence of hydrate, so as to promote the decomposition of hydrate into water in the place of occurrence. and natural gas, and then use the natural gas extraction process to collect and transport the decomposed natural gas to the ground. The key to the underground exploitation of natural gas hydrates is how to take cost-effective measures to promote the decomposition of hydrates while keeping the bottom of the well stable so that methane does not leak or cause the greenhouse effect. The currently proposed methods mainly include thermal excitation method, depressurization method and chemical method.

热激发法主要是将蒸汽、热水、热盐水等载热体注入水合物储层，使温度达到水合物分解温度以上。美国专利US6994159B2及日本专利JP09158662分别提出通过开采井向水合物储层注入热水、蒸汽等热流体促进水合物分解，但热激发法的主要缺点在于载热流体从海面输送至海底，沿程热损失大，热能利用率低。中国专利CN1609409A提出了一种利用微波加热开采天然气水合物的方法及装置，美国专利US6148911提出采用井下电加热开采天然水合物，但这些方法均需采用电能加热，能源利用效率低，同时开采装置复杂。The thermal excitation method is mainly to inject heat carriers such as steam, hot water, and hot brine into the hydrate reservoir to make the temperature reach above the hydrate decomposition temperature. U.S. Patent US6994159B2 and Japanese Patent JP09158662 propose to inject thermal fluids such as hot water and steam into hydrate reservoirs through production wells to promote hydrate decomposition. The loss is large and the utilization rate of heat energy is low. Chinese patent CN1609409A proposes a method and device for exploiting natural gas hydrates by using microwave heating, and U.S. patent US6148911 proposes mining natural gas hydrates by underground electric heating, but these methods all require electric heating, which has low energy utilization efficiency and complicated mining devices .

化学法主要是向水合物储层注入盐水、甲醇、乙醇、乙二醇等化学物质，改变水的活度，从而改变水合物形成的相平衡条件，降低水合物稳定温度，促进天然气水合物的分解，化学法的缺点是药剂用量大，成本高，大量使用化学药剂也会造成环境污染问题。在开采过程中，必须保证水合物储层的药剂浓度，由于水合物分解释放大量结晶水，造成药剂浓度不断降低，同时，由于水合物分解为吸热反应，水合物层的温度会随着开采过程的进行而不断降低，从而导致开采效率降低，所需化学药剂的浓度也不断升高。The chemical method is mainly to inject brine, methanol, ethanol, ethylene glycol and other chemical substances into the hydrate reservoir to change the activity of water, thereby changing the phase equilibrium conditions of hydrate formation, reducing the stable temperature of hydrate, and promoting the formation of natural gas hydrate. Decomposition, the disadvantage of the chemical method is that the amount of medicament is large, the cost is high, and the use of a large amount of chemical medicament will also cause environmental pollution problems. During the mining process, the chemical concentration of the hydrate reservoir must be guaranteed. Because the hydrate decomposes and releases a large amount of crystal water, the chemical concentration is continuously reduced. At the same time, because the hydrate decomposition is an endothermic reaction, the temperature of the hydrate layer will decrease with The progress of the process is continuously reduced, resulting in a decrease in mining efficiency and an increase in the concentration of required chemicals.

美国专利US2005/0121200A1公开了一种采用CO₂置换法开采甲烷水合物，同时实现对温室效应气体CO₂的安全稳定填埋。由于CO₂水合物形成的温度高于甲烷，压力低于甲烷，因此，只要控制天然气水合物储层的温压条件处于CO₂水合物形成的稳定区和CH₄水合物的不稳定区就能实现CO₂对CH₄水合物的自动置换开采。CO₂水合物生成热为57.98KJ/mol，甲烷水合物的分解热为54.49KJ/mol，甲烷水合物分解所需的热量完全可由CO₂水合物生成所放出的热量来提供，同时，CO₂水合物的及时回填有利于保持井底地质条件稳定，防止塌陷和滑坡。但CO₂置换法存在的问题是形成的CO₂水合物固体倾向于包裹在甲烷水合物的外表面，从而导致对天然气水合物分解不彻底，置换反应速度极其缓慢。US Patent US2005/0121200A1 discloses a CO₂ replacement method for mining methane hydrate, while realizing safe and stable landfill of the greenhouse gas CO₂ . Since the temperature of_CO2 hydrate formation is higher than that of methane, and the pressure is lower than that of methane, therefore, as long as the temperature and pressure conditions of the natural gas hydrate reservoir are controlled in the stable zone of_CO2 hydrate formation and the unstable zone of_CH4 hydrate Realize the automatic displacement mining of CO₂ to CH_hydrate . The heat of formation of CO₂ hydrate is 57.98KJ/mol, and the heat of decomposition of methane hydrate is 54.49KJ/mol. The heat required for the decomposition of methane hydrate can be completely provided by the heat released by the formation of CO₂ hydrate. At the same time, CO₂ The timely backfilling of hydrate is beneficial to keep the geological conditions at the bottom of the well stable and prevent subsidence and landslides. However, the problem with the CO₂ replacement method is that the formed CO₂ hydrate solid tends to coat the outer surface of the methane hydrate, which leads to incomplete decomposition of the natural gas hydrate and an extremely slow replacement reaction.

降压法是通过降低水合物储层的压力，引起天然气水合物移动至不稳定区而分解，这种方法由于海底地质条件千差万别，往往难以达到水合物分解的温压条件，同时开采速度慢，效率低。The depressurization method is to reduce the pressure of the hydrate reservoir to cause the natural gas hydrate to move to the unstable area and decompose. Due to the wide variety of seabed geological conditions, it is often difficult to achieve the temperature and pressure conditions for hydrate decomposition. At the same time, the production speed is slow. low efficiency.

中国专利CN1294648A提出采用高压气流冲击水合物储层，并通过气流夹带输送固体天然气水合物至海面。中国专利CN1587642A参照陆地矿山采矿分选模式提出采用水下自动挖掘机械开采固体天然气水合物、然后采用泥沙分离，水合物分解等工艺开采天然气水合物，这些地上分解开采方法均存在开采范围小，水下自动开采设备技术要求高，对海底地质构造破坏严重，容易引起井底塌陷、滑坡等问题。Chinese patent CN1294648A proposes to use high-pressure gas flow to impact hydrate reservoirs, and transport solid natural gas hydrate to the sea surface through gas flow entrainment. Chinese patent CN1587642A refers to the mining and separation mode of land mines and proposes to use underwater automatic excavation machinery to mine solid natural gas hydrate, and then use sediment separation, hydrate decomposition and other processes to mine natural gas hydrate. These ground decomposition mining methods all have a small mining range, Underwater automatic mining equipment has high technical requirements, which seriously damages the geological structure of the seabed, and is likely to cause problems such as well bottom collapse and landslides.

迄今为止，还没有一种经济而有效的方法可以用来实现天然气水合物的大规模工业化开采。各种水合物开采方法各有优缺点，单纯采用某一种开采方法很难实现对天然气水合物的经济有效开采，必须综合各种方法的优点，取长补短才能达到对天然气水合物的经济、高效、安全开采。So far, there is no economical and effective method for large-scale industrial production of gas hydrates. All kinds of hydrate mining methods have their own advantages and disadvantages. It is difficult to achieve economical and effective mining of natural gas hydrate by simply using a certain mining method. It is necessary to integrate the advantages of various methods and learn from each other to achieve economical, efficient, and efficient natural gas hydrate production. Mining safely.

发明内容Contents of the invention

本发明的目的在于提供一种经济、高效、安全的原位催化氧化热化学法开采天然气水合物的方法及装置，实现海洋天然气水合物大规模、工业化开采，同时本发明也可应用于陆地永冻土地带天然气水合物的开采。The purpose of the present invention is to provide an economical, efficient, and safe in-situ catalytic oxidation thermochemical method and device for exploiting natural gas hydrate, so as to realize large-scale and industrialized exploitation of marine natural gas hydrate. At the same time, the present invention can also be applied to land permanent Exploitation of gas hydrate in permafrost zone.

为达到上述目的，本发明采取了以下的技术方案：To achieve the above object, the present invention has taken the following technical solutions:

1)构筑开采井及集气井。首先采用深水钻井技术领域的现有技术在水合物成矿区构筑开采井及集气井，并构筑开采井与集气井之间的连接通道；开采井及集气井贯穿至水合物储层底部。1) Construct production wells and gas gathering wells. First, use the existing technology in the field of deep-water drilling technology to construct production wells and gas-gathering wells in the hydrate mineralization area, and construct the connecting channel between the production wells and gas-gathering wells; the production wells and gas-gathering wells penetrate to the bottom of the hydrate reservoir.

2)天然气水合物分解。向水合物储层注入水合物分解促进剂，将天然气水合物分解为天然气和水，同时在安装于开采井下的催化氧化燃烧器中采用氧化剂原位催化氧化燃烧燃料加热载热流体，然后将载热流体泵入水合物储层供给天然气水合物分解所需的热能，将催化氧化燃烧所产生的CO₂气体注入水合物储层，使其形成CO₂水合物填充甲烷水合物开采后留下的空隙，CO₂水合物生成所释放的热量传递给水合物分解促进剂，用于天然气水合物的分解，CO₂水合物形成吸收分解促进剂中的水份，提高了水合物分解促进剂的浓度。2) Decomposition of natural gas hydrate. A hydrate decomposition accelerator is injected into the hydrate reservoir to decompose the natural gas hydrate into natural gas and water. At the same time, the in-situ catalytic oxidation combustion fuel is used to heat the heat-carrying fluid with an oxidant in the catalytic oxidation burner installed in the production well, and then the The heat fluid is pumped into the hydrate reservoir to supply the thermal energy required for the decomposition of natural gas hydrate, and the CO₂ gas produced by catalytic oxidation combustion is injected into the hydrate reservoir to form CO_hydrate to fill the gas left after the mining of methane hydrate The heat released by the formation of CO₂ hydrate is transferred to the hydrate decomposition accelerator for the decomposition of natural gas hydrate, and the CO₂ hydrate is formed to absorb the water in the decomposition accelerator, increasing the concentration of the hydrate decomposition accelerator .

3)分解后的天然气导出。通过天然气导出管道将分解后的天然气收集至海面上的分离、储气装置。3) The decomposed natural gas is exported. The decomposed natural gas is collected to the separation and storage device on the sea surface through the natural gas export pipeline.

本发明方法中，所述步骤(1)及步骤(3)均采用现有技术，步骤(2)天然气水合物分解为本发明的创新点。In the method of the present invention, the step (1) and the step (3) both adopt the prior art, and the step (2) of natural gas hydrate decomposition is an innovative point of the present invention.

所述步骤(2)天然气水合物分解可以具体细化为以下步骤：The step (2) of natural gas hydrate decomposition can be specifically refined into the following steps:

(1)催化氧化燃烧器采用电加热点火预热；(1) The catalytic oxidation burner adopts electric heating to ignite and preheat;

(2)向安装于开采井中的催化氧化燃烧器输送燃料及氧化剂，燃料及氧化剂在预热器中预热；(2) Deliver fuel and oxidant to the catalytic oxidation burner installed in the production well, and the fuel and oxidant are preheated in the preheater;

(3)在催化剂作用下，燃料在井下催化氧化燃烧器中被氧化剂催化氧化，放出热量加热载热流体；(3) Under the action of the catalyst, the fuel is catalyzed and oxidized by the oxidant in the downhole catalytic oxidation burner, and heat is released to heat the heat-carrying fluid;

(4)向天然气水合物储层注入水合物分解促进剂，将天然气水合物分解为天然气和水；(4) Injecting a hydrate decomposition accelerator into the natural gas hydrate reservoir to decompose the natural gas hydrate into natural gas and water;

(5)载热流体输送至水合物储层加热水合物分解促进剂及天然气水合物储层，促进天然气水合物的分解；(5) The heat-carrying fluid is transported to the hydrate reservoir to heat the hydrate decomposition accelerator and the natural gas hydrate reservoir to promote the decomposition of natural gas hydrate;

(6)将催化氧化燃烧产物输送至水合物储层，控制水合物储层温度低于CO₂水合物稳定温度，高于CH₄水合物稳定温度；(6) Transport the catalytic oxidation combustion product to the hydrate reservoir, and control the temperature of the hydrate_reservoir to be lower than the stable temperature of CO₂ hydrate and higher than the stable temperature of CH hydrate;

(7)催化氧化燃烧产物中的CO₂在水合物储层形成CO₂水合物，放出水合物生成热加热水合物分解促进剂；(7)_CO2 in the catalytic oxidation combustion product forms_CO2 hydrate in the hydrate reservoir, and releases the hydrate to generate heat and heat the hydrate decomposition accelerator;

(8)CO₂水合物形成吸收水合物分解促进剂中的水份，水合物分解促进剂浓度升高，对天然气水合物的分解速率加快。(8) CO₂ hydrate forms and absorbs water in the hydrate decomposition accelerator, and the concentration of the hydrate decomposition accelerator increases, and the decomposition rate of natural gas hydrate is accelerated.

所述水合物分解促进剂是低碳醇或多元醇或盐水或其混合溶液；The hydrate decomposition accelerator is low-carbon alcohol or polyhydric alcohol or salt water or a mixed solution thereof;

所述水合物分解促进剂同时含有0.1-2％的表面活性剂；The hydrate decomposition accelerator also contains 0.1-2% surfactant;

所述低碳醇为甲醇或乙醇或异丙醇或其混合溶液；多元醇为乙二醇或二甘醇或三甘醇或丙三醇或其混合物；所述醇溶液的浓度为20-60％。The low-carbon alcohol is methanol or ethanol or isopropanol or a mixed solution thereof; polyol is ethylene glycol or diethylene glycol or triethylene glycol or glycerol or a mixture thereof; the concentration of the alcohol solution is 20-60 %.

所述盐水的阳离子为K⁺、Na⁺、Ca²⁺、Mg²⁺，NH₄⁺，阴离子为F^-、Cl^-、Br^-、PO₄^3-、草酸根、乙酸根；所述盐水的浓度为10-60％。The cations of the brine are K⁺ , Na⁺ , Ca²⁺ , Mg²⁺ , NH₄⁺ , and the anions are F^- , Cl^- , Br^- , PO₄^3- , oxalate, acetate; the brine The concentration is 10-60%.

所述表面活性剂为直链、支链或交链有机高分子聚合物或其混合物，聚合物中至少含有一个或多个N、P、O、S杂原子的亲水极性官能团；所述表面活性剂优选含N杂原子的聚乙烯基吡咯烷酮、聚乙烯基己内酰胺、聚醚胺、聚多烷基多胺、聚丙烯酰胺、聚二烷基二烯丙基氯化胺、高碳链季胺盐。The surfactant is a linear, branched or cross-chained organic polymer or a mixture thereof, and the polymer contains at least one or more hydrophilic polar functional groups of N, P, O, S heteroatoms; the The surfactant is preferably polyvinylpyrrolidone containing N heteroatoms, polyvinylcaprolactam, polyetheramine, polypolyalkylpolyamine, polyacrylamide, polydialkyldiallylamine chloride, high carbon chain quaternary amine salt.

所述载热流体是水或盐水或水合物分解促进剂或其混合物；The heat-carrying fluid is water or brine or a hydrate decomposition accelerator or a mixture thereof;

所述水合物分解促进剂和载热流体可以分别经不同的管道输送至水合物储层和催化氧化燃烧器，分解促进剂和载热流体也可以先在海面移动平台上混合后经同一管道输送至催化氧化燃烧器加热至40-90℃后输送至水合物储层。The hydrate decomposition accelerator and the heat-carrying fluid can be transported to the hydrate reservoir and the catalytic oxidation burner through different pipelines respectively, and the decomposition accelerator and the heat-carrying fluid can also be mixed on the sea surface mobile platform first and then transported through the same pipeline After being heated to 40-90°C by the catalytic oxidation burner, it is transported to the hydrate reservoir.

本发明原位催化氧化热化学法开采天然气水合物的装置，包括开采井13和集气井6及开采井13与集气井6之间的水平连接通道，以及储气罐7及天然气输送管道，其特征在于：还包括催化氧化燃烧器14，催化氧化燃烧器14安装在开采井中13，燃料罐8、分解促进剂储罐9、载热体储罐10分别经管道连接催化氧化燃烧器14，催化氧化燃烧器14内设有点火装置22，催化氧化燃烧器14的催化燃烧产物出口管27连接至水平连接通道的底部，催化氧化燃烧器14上另设有分解促进剂及载热流体出口管19。The device for exploiting natural gas hydrate by the in-situ catalytic oxidation thermochemical method of the present invention comprises aproduction well 13 and a gas collection well 6, a horizontal connecting channel between the production well 13 and the gas collection well 6, a gas storage tank 7 and a natural gas transmission pipeline, which It is characterized in that: it also includes acatalytic oxidation burner 14, thecatalytic oxidation burner 14 is installed in the production well 13, thefuel tank 8, the decompositionaccelerator storage tank 9, and the heatcarrier storage tank 10 are respectively connected to thecatalytic oxidation burner 14 through pipelines, and thecatalytic oxidation burner 14 is connected to thecatalytic oxidation burner 14. Theoxidation burner 14 is provided with anignition device 22, the catalytic combustionproduct outlet pipe 27 of thecatalytic oxidation burner 14 is connected to the bottom of the horizontal connection channel, and thecatalytic oxidation burner 14 is additionally provided with a decomposition accelerator and a heat-carryingfluid outlet pipe 19 .

所述催化氧化燃烧器14为一同轴套管反应器，催化氧化燃烧器内管18管程为催化氧化燃烧区，催化氧化燃烧器内管18与外层套管之间的壳程分为两段独立区间，其中一段为燃烧器预热段24，用于燃料及氧化剂的预热处理，另一段为燃烧器换热段26，用于载热流体的加热。所述燃料罐8通过燃料及氧化剂进口管21连接至燃烧器预热段24，分解促进剂储罐9和载热体储罐10通过分解促进剂及载热流体进口管25连接至燃烧器换热段26，催化氧化燃烧器进口管23连接燃烧器预热段24及催化氧化燃烧器内管18；所述的催化氧化燃烧器内管18由多根内管固定在管板上组成列管式反应器，催化剂负载于反应器内管壁上；催化燃烧产物出口管27连通催化氧化燃烧器内管18，分解促进剂及载热流体出口管19连通外套管。Thecatalytic oxidation burner 14 is a coaxial casing reactor, theinner pipe 18 of the catalytic oxidation burner is a catalytic oxidation combustion zone, and the shell pass between theinner pipe 18 and the outer casing of the catalytic oxidation burner is divided into There are two separate sections, one of which is theburner preheating section 24 for preheating treatment of fuel and oxidant, and the other section is the burnerheat exchange section 26 for heating the heat-carrying fluid. Thefuel tank 8 is connected to theburner preheating section 24 through a fuel andoxidant inlet pipe 21, and the decompositionaccelerator storage tank 9 and the heatcarrier storage tank 10 are connected to the burner exchange unit through a decomposition accelerator and a heat transferfluid inlet pipe 25. Thehot section 26, theinlet pipe 23 of the catalytic oxidation burner is connected to theburner preheating section 24 and theinner pipe 18 of the catalytic oxidation burner; theinner pipe 18 of the catalytic oxidation burner is composed of multiple inner pipes fixed on the tube plate to form a tube array The catalyst is loaded on the inner tube wall of the reactor; theoutlet pipe 27 of the catalytic combustion product is connected to theinner pipe 18 of the catalytic oxidation burner, and theoutlet pipe 19 of the decomposition accelerator and the heat-carrying fluid is connected to the outer casing.

所述催化氧化燃烧器内管18也可以是由多根内管固定在管板上组成的列管式反应器，催化剂负载于反应器内管壁上。为加大传热速率和催化剂的负载面积，增大催化剂与反应物的接触面积，缩小催化反应器的体积，反应器的内管可采用翅片管。Theinner tube 18 of the catalytic oxidation burner may also be a tube-and-tube reactor composed of multiple inner tubes fixed on the tube sheet, and the catalyst is loaded on the inner tube wall of the reactor. In order to increase the heat transfer rate and the loading area of the catalyst, increase the contact area between the catalyst and the reactant, and reduce the volume of the catalytic reactor, the inner tube of the reactor can be a finned tube.

催化氧化燃烧器开始工作前先采用电加热点火装置预热至500-900℃，然后关闭点火装置，通入燃料及氧化剂；Before the catalytic oxidation burner starts working, use an electric heating ignition device to preheat to 500-900°C, then turn off the ignition device, and feed fuel and oxidant;

所述燃料为甲烷、天然气、石油气等低碳烃类燃料，氧化剂为空气或富氧空气，燃料和氧化剂经不同管道输送至催化氧化燃烧器，也可以将燃料与氧化剂先在海面上混合后，再输送到预热器预热至400-600℃，预热后的气体进入催化氧化燃烧器在催化剂的作用下发生氧化反应，放出反应热，燃烧后的产物通过带有止逆装置的管道输送至水合物储层；The fuel is methane, natural gas, petroleum gas and other low-carbon hydrocarbon fuels, and the oxidant is air or oxygen-enriched air. The fuel and oxidant are transported to the catalytic oxidation burner through different pipelines, and the fuel and oxidant can also be mixed on the sea surface first. , and then transported to the preheater to preheat to 400-600°C. The preheated gas enters the catalytic oxidation burner and undergoes oxidation reaction under the action of the catalyst, releasing the heat of reaction. The burned product passes through the pipeline with the non-return device transported to hydrate reservoirs;

催化氧化所放出的反应热在换热器段加热载热流体，载热流体通过管道输送至水合物储层加热水合物分解促进剂；The reaction heat released by catalytic oxidation heats the heat transfer fluid in the heat exchanger section, and the heat transfer fluid is transported to the hydrate reservoir through the pipeline to heat the hydrate decomposition accelerator;

烃类燃料和氧化剂也可以通过各自独立的管道输送至预热器后混和；Hydrocarbon fuel and oxidant can also be mixed after being transported to the preheater through separate pipelines;

通过控制烃类燃料和氧化剂的流量、配比以及载热流体流量来控制催化氧化燃烧器内的温度为600-1000℃，温度过高会使催化剂失活，温度过低，燃料氧化不充分；Control the temperature in the catalytic oxidation burner to 600-1000°C by controlling the flow rate and proportion of hydrocarbon fuel and oxidant, and the flow rate of heat-carrying fluid. If the temperature is too high, the catalyst will be deactivated; if the temperature is too low, the fuel oxidation will be insufficient;

通过控制烃类燃料和氧化剂的流量以及配比来控制载热流体的温度，通过调整载热流体的温度来控制水合物储层的温度处于甲烷水合物的稳定温度以上，CO₂水合物的稳定温度以下；The temperature of the heat-carrying fluid is controlled by controlling the flow rate and ratio of hydrocarbon fuel and oxidant, and the temperature of the hydrate reservoir is controlled by adjusting the temperature of the heat-carrying fluid to be above the stable temperature of methane hydrate, and the stability of CO₂ hydrate below temperature;

催化燃烧后的氧化产物中的CO₂在水合物储层生成CO₂水合物，放出的热量用于加热水合物分解促进剂，同时CO₂水合物生成过程吸收水合物分解促进剂中的水份，提高水合物分解促进剂的浓度，避免了促进剂浓度降低导致水合物分解速率减小。The_CO2 in the oxidation product after catalytic combustion generates_CO2 hydrate in the hydrate reservoir, and the heat released is used to heat the hydrate decomposition accelerator, and at the same time, the_CO2 hydrate formation process absorbs the water in the hydrate decomposition accelerator , increasing the concentration of the hydrate decomposition accelerator, avoiding the reduction of the hydrate decomposition rate caused by the decrease of the accelerator concentration.

所生成的CO₂水合物的密度大于载热流体及水合物分解促进剂的密度，生成的CO₂水合物自动沉积于底层，填充因天然气水合物开采所留下的空间，有利于保持海底地质构造稳定，避免海底塌陷、滑坡等地质灾害发生；The density of the generated CO₂ hydrate is greater than that of the heat-carrying fluid and the hydrate decomposition accelerator, and the generated CO₂ hydrate is automatically deposited on the bottom layer, filling the space left by the exploitation of natural gas hydrate, which is conducive to maintaining the geological environment of the seabed. The structure is stable, avoiding geological disasters such as submarine subsidence and landslides;

CO₂水合物和天然气水合物因密度差异而被载热流体和水合物分解促进剂隔开，很好地避免了因CO₂水合物在天然气水合物外表包覆而导致天然气水合物分解速率减慢，分解温度升高、开采效率降低的现象发生。CO₂ hydrate and gas hydrate are separated by the heat transfer fluid and the hydrate decomposition accelerator due to the difference in density, which can well avoid the reduction in the decomposition rate of gas hydrate caused by the coating of CO₂ hydrate on the surface of gas hydrate. slow, the decomposition temperature rises and the extraction efficiency decreases.

所述催化剂为Pt、Rh、La、Mn、Ni、Cr等之一的金属或金属氧化物或金属和金属氧化物的混合物担载于α-Al₂O₃颗粒或γ-Al₂O₃颗粒表面而制得，然后将催化剂负载于燃烧器内管壁或翅片上。The catalyst is one of Pt, Rh, La, Mn, Ni, Cr, etc. metal or metal oxide or a mixture of metal and metal oxide supported on α-Al₂ O₃ particles or γ-Al₂ O₃ particles The surface is prepared, and then the catalyst is supported on the inner tube wall or fins of the burner.

所述催化氧化燃烧器可以立式安装在垂直开采井的底部，也可以卧式安装在水平开采井中；催化氧化燃烧器可随着开采平面的上升而在井筒中向上移动。The catalytic oxidation burner can be installed vertically at the bottom of the vertical production well, and can also be installed horizontally in the horizontal production well; the catalytic oxidation burner can move upward in the wellbore as the production plane rises.

本发明克服了现有技术天然气水合物开采方法存在的问题，采用原位催化氧化加热解决了传统热激发法热量损失大，开采效率低的缺点，同时采用化学法和CO₂置换相结合，加快了开采速率、大大降低化学注剂的用量，同时有效地保证了海底地质的稳定，避免了地质及环境灾害的发生。The invention overcomes the problems existing in the natural gas hydrate mining method in the prior art, adopts in-situ catalytic oxidation heating to solve the shortcomings of the traditional thermal excitation method, such as large heat loss and low mining efficiency, and simultaneously adopts the combination of chemical method and_CO2 replacement to speed up Improve the mining rate, greatly reduce the amount of chemical injection, and effectively ensure the stability of the seabed geology, avoiding the occurrence of geological and environmental disasters.

附图说明Description of drawings

附图1为本发明开采工艺及装置简图；Accompanying drawing 1 is mining technique of the present invention and device schematic diagram;

附图2为本发明实施例催化氧化燃烧器14的B-B向视图；Accompanying drawing 2 is the B-B direction view ofcatalytic oxidation burner 14 of the embodiment of the present invention;

附图3为本发明实施例催化氧化燃烧器14的A-A向视图；Accompanying drawing 3 is the A-A direction view ofcatalytic oxidation burner 14 of the embodiment of the present invention;

附图标记说明：1、海底岩石层，2、CO₂水合物，3、天然气水合物储层，4、海底沉积物层，5、海水层，6、集气井，7、储气罐，8、燃料罐，9、分解促进剂储罐、10、载热体储罐，11、海上移动平台，12、控制系统，13、开采井，14、催化氧化燃烧器，15、化学分解促进剂及载热流体层，16、止回装置，17、催化剂，18、催化氧化燃烧器内管，19、分解促进剂及载热流体出口管，20、外管，21、燃料及氧化剂进口管，22、点火装置，23、催化氧化燃烧器进口管，24、燃烧器预热段，25、分解促进剂及载热流体进口管，26、燃烧器换热段，27、催化燃烧产物出口管，28、翅片。Explanation of reference numerals: 1, seabed rock layer, 2, CO₂ hydrate, 3, natural gas hydrate reservoir, 4, seabed sediment layer, 5, seawater layer, 6, gas gathering well, 7, gas storage tank, 8 , Fuel tank, 9. Decomposition promoter storage tank, 10. Heat carrier storage tank, 11. Offshore mobile platform, 12. Control system, 13. Production well, 14. Catalytic oxidation burner, 15. Chemical decomposition promoter and Heat-carrying fluid layer, 16, check device, 17, catalyst, 18, inner pipe of catalytic oxidation burner, 19, decomposition accelerator and heat-carrying fluid outlet pipe, 20, outer pipe, 21, fuel and oxidant inlet pipe, 22 , ignition device, 23, catalytic oxidation burner inlet pipe, 24, burner preheating section, 25, decomposition accelerator and heat transfer fluid inlet pipe, 26, burner heat exchange section, 27, catalytic combustion product outlet pipe, 28 , fins.

具体实施方式Detailed ways

下面结合附图详细说明本发明的具体实施方式：The specific embodiment of the present invention is described in detail below in conjunction with accompanying drawing:

如图1、2、3所示，首先采用深水钻井技术在海底构筑开采井13及集气井6，同时打通开采井与集气井之间的水平连接通道，开采井13及集气井6穿过海水层5和海底沉积物层4贯穿至天然气水合物储层3底部。将催化氧化燃烧器14安装在开采井中。开采过程中，先将体积比为1∶10的CH₄与空气在燃料罐8中混合，混合燃料气经燃料及氧化剂进口管21进入燃烧器预热段24，预热至400-600℃，然后经催化氧化燃烧器进口管23进入催化氧化燃烧器内管18。催化氧化燃烧器内管18由多根内设有翅片28的内管固定在管板上组成列管式反应器，催化剂17负载于反应器内管壁和翅片28上，催化剂为Pt、Rh、La、Mn、Ni、Cr等之一的金属或金属氧化物或金属和金属氧化物的混合物担载于α-Al₂O₃颗粒或γ-Al₂O₃颗粒表面而制得。预热过的混合燃料气在催化剂17表面发生催化氧化反应。分解促进剂储罐9和载热体储罐10通过分解促进剂及载热流体进口管25连接至燃烧器换热段26，水合物分解促进剂为低碳醇或多元醇或盐水或其混合溶液；水合物分解促进剂同时含有0.1-2％的表面活性剂，载热流体为水或盐水或水合物分解促进剂或其混合物。催化氧化燃烧器内管18中的温度为600-1000℃，反应放出的热量一部分用于燃烧器预热段24预热混合燃料气，另一部分用于在燃烧器换热段26加热载热流体及分解促进剂至60-90℃，加热后的分解促进剂及载热流体沿水平通道输送至天然气水合物储层3将天然气水合物分解为天然气和水，天然气经集气井6收集至海上移动平台11，储存于储气罐7；天然气水合物分解过程中大量水份释放导致化学分解促进剂及载热流体层15中的促进剂浓度不断降低，水合物分解速率降低；催化氧化燃烧器燃烧后的氧化产物经出口管27及止回装置16输送至水平连接通道的底部，氧化产物中的CO₂在此生成CO₂水合物2，并填充天然气水合物开采后留下的空隙；CO₂水合物形成过程中放出的热量传递给化学分解促进剂及载热流体层15，同时CO₂水合物形成从化学分解促进剂及载热流体层吸收了大量水份，导致化学分解促进剂的浓度上升，化学促进剂对天然气水合物的分解速率增大，因此在本发明水合物开采过程中，化学分解促进剂的浓度能一直维持在正常工作浓度以上。As shown in Figures 1, 2, and 3, firstly, the deepwater drilling technology is used to construct the production well 13 and the gas collection well 6 on the seabed, and at the same time, the horizontal connection channel between the production well and the gas collection well is opened, so that the production well 13 and the gas collection well 6 pass through theseawater Layer 5 andseabed sediment layer 4 penetrate to the bottom ofgas hydrate reservoir 3 . Acatalytic oxidation burner 14 is installed in the production well. During the mining process,_CH4 with a volume ratio of 1:10 is first mixed with air in thefuel tank 8, and the mixed fuel gas enters theburner preheating section 24 through the fuel andoxidant inlet pipe 21, and is preheated to 400-600°C. Then enter theinner pipe 18 of the catalytic oxidation burner through theinlet pipe 23 of the catalytic oxidation burner. Theinner tube 18 of the catalytic oxidation burner consists of a plurality of inner tubes withfins 28 fixed on the tube plate to form a tubular reactor. Thecatalyst 17 is loaded on the inner tube wall and thefins 28 of the reactor. The catalyst is Pt, One of Rh, La, Mn, Ni, Cr and other metals or metal oxides or a mixture of metals and metal oxides is supported on the surface of α-Al₂ O₃ particles or γ-Al₂ O₃ particles. The preheated mixed fuel gas undergoes a catalytic oxidation reaction on the surface of thecatalyst 17 . The decompositionaccelerator storage tank 9 and the heatcarrier storage tank 10 are connected to the burnerheat exchange section 26 through the decomposition accelerator and the heat transferfluid inlet pipe 25, and the hydrate decomposition accelerator is low-carbon alcohol or polyol or salt water or a mixture thereof The solution; the hydrate decomposition accelerator contains 0.1-2% of surfactant at the same time, and the heat-carrying fluid is water or brine or the hydrate decomposition accelerator or a mixture thereof. The temperature in the inner tube 18 of the catalytic oxidation burner is 600-1000°C, part of the heat released by the reaction is used to preheat the mixed fuel gas in the preheating section 24 of the burner, and the other part is used to heat the heat transfer fluid in the heat exchange section 26 of the burner and decomposition accelerator to 60-90°C, the heated decomposition accelerator and heat-carrying fluid are transported to the natural gas hydrate reservoir 3 along the horizontal channel to decompose the natural gas hydrate into natural gas and water, and the natural gas is collected by the gas collection well 6 and moved offshore The platform 11 is stored in the gas storage tank 7; a large amount of water is released during the decomposition of natural gas hydrate, which leads to the continuous decrease of the concentration of the chemical decomposition accelerator and the accelerator in the heat-carrying fluid layer 15, and the reduction of the hydrate decomposition rate; the catalytic oxidation burner burns The final oxidation product is transported to the bottom of the horizontal connection channel through the outlet pipe 27 and the non-return device 16, where the CO₂ in the oxidation product generates_CO hydrate 2 and fills the gap left after the natural gas hydrate is exploited; the CO₂ The heat released during the hydrate formation process is transferred to the chemical decomposition accelerator and the heat-carrying fluid layer 15, and at the same time, the formation of_CO2 hydrate absorbs a large amount of water from the chemical decomposition accelerator and the heat-carrying fluid layer, resulting in the concentration of the chemical decomposition accelerator As the rate rises, the decomposition rate of the natural gas hydrate by the chemical accelerator increases, so the concentration of the chemical decomposition accelerator can always be maintained above the normal working concentration during the hydrate production process of the present invention.

在水合物开采起始阶段，催化氧化燃烧器内管18温度低，催化氧化反应难以进行，在进行催化氧化燃烧之前先采用电加热点火装置22加热催化氧化燃烧器管内温度至500-900℃，然后关闭电加热点火装置22，通入混合燃料，进入正常开采运行阶段。In the initial stage of hydrate mining, the temperature of theinner tube 18 of the catalytic oxidation burner is low, and the catalytic oxidation reaction is difficult to carry out. Before the catalytic oxidation combustion is carried out, the electricheating ignition device 22 is used to heat the temperature inside the catalytic oxidation burner tube to 500-900°C. Then close the electricheating ignition device 22, feed the mixed fuel, and enter the normal mining operation stage.

Claims (9)

1. the method for a natural gas hydrate exploitation with in-situ catalytic oxidation thermochemistry comprises that step (1) constructs recovery well and gas collection well; (2) gas hydrates decompose; (3) natural gas after the decomposition is derived, and it is characterized in that described step (2) gas hydrates decompose the following method of taking: inject decomposition of hydrate accelerator to the hydrate reservoir, gas hydrates are decomposed into natural G﹠W; Adopt oxidant in-situ catalytic oxidation combustion fuel heating heat transport fluid simultaneously in the catalytic oxidation combustion device under being installed on recovery well, then heat transport fluid is pumped into the hydrate reservoir and supply with the required heat energy of gas hydrates decomposition; With the CO that catalytic oxidation combustion produced₂Gas injects the hydrate reservoir, makes it form CO₂Hydrate is filled the space that stays after the methane hydrate exploitation; CO₂Hydrate generates the heat transferred decomposition of hydrate accelerator that is discharged, and is used for the decomposition of gas hydrates, CO₂Hydrate forms the moisture content that absorbs in the decomposition accelerating agent, has improved the concentration of decomposition of hydrate accelerator.

2. the method for natural gas hydrate exploitation with in-situ catalytic oxidation thermochemistry as claimed in claim 1 is characterized in that described step (2) gas hydrates decompose may further comprise the steps:

(1) the catalytic oxidation combustion device adopts the electrical heating combustion preheater;

(2) catalytic oxidation combustion device transfer the fuel and the oxidant in being installed on recovery well, the preheating in preheater of fuel and oxidant;

(3) under catalyst action, fuel is oxidized dose of catalytic oxidation in the catalytic oxidation combustion device of down-hole, emits heat heating heat transport fluid;

(4) inject decomposition of hydrate accelerator to the gas hydrates reservoir, gas hydrates are decomposed into natural G﹠W;

(5) heat transport fluid is delivered to hydrate reservoir heating decomposition of hydrate accelerator and gas hydrates reservoir, promotes the decomposition of gas hydrates;

(6) the catalytic oxidation combustion product is delivered to the hydrate reservoir, control hydrate reservoir temperature is lower than CO₂The hydrate equilibrium temperature is higher than CH₄The hydrate equilibrium temperature;

(7) CO in the catalytic oxidation combustion product₂Form CO at the hydrate reservoir₂Hydrate is emitted hydrate and is generated heat heating decomposition of hydrate accelerator;

(8) CO₂Hydrate forms the moisture content that absorbs in the decomposition of hydrate accelerator, and the decomposition of hydrate promoter concentration raises, and the decomposition rate of gas hydrates is accelerated.

3. the method for natural gas hydrate exploitation with in-situ catalytic oxidation thermochemistry as claimed in claim 1 or 2, it is characterized in that: described heat transport fluid is water or salt solution or decomposition of hydrate accelerator or its mixture.

4. the method for natural gas hydrate exploitation with in-situ catalytic oxidation thermochemistry as claimed in claim 1 or 2, it is characterized in that: supported catalyst in the described catalytic oxidation combustion device, described catalyzer are that the metal of one of Pt, Rh, La, Mn, Ni, Cr or the mixture of metal oxide or metal and metal oxide support in α-Al₂O₃Particle or γ-Al₂O₃Particle surface and making.

5. the method for natural gas hydrate exploitation with in-situ catalytic oxidation thermochemistry as claimed in claim 2, it is characterized in that: described catalytic oxidation combustion device electrical heating combustion preheater temperature is 500-900 ℃, the preheating of fuel temperature is 400-600 ℃, and the catalytic oxidation combustion temperature is 600-1000 ℃.

6. the device of a natural gas hydrate exploitation with in-situ catalytic oxidation thermochemistry, comprise the horizontal interface channel between recovery well (13) and gas collection well (6) and recovery well (13) and the gas collection well (6), and gasholder (7) and natural-gas transfer pipeline, it is characterized in that: also comprise catalytic oxidation combustion device (14), catalytic oxidation combustion device (14) is installed in (13) in the recovery well, fuel tank (8), decomposition accelerating agent storage tank (9), thermophore storage tank (10) connects catalytic oxidation combustion device (14) through pipeline respectively, be provided with igniter (22) in the catalytic oxidation combustion device (14), the catalytic combustion product outlet (27) of catalytic oxidation combustion device (14) is connected to the bottom of horizontal interface channel, is provided with decomposition accelerating agent and heat transport fluid outlet (19) on the catalytic oxidation combustion device (14) in addition.

7. the device of natural gas hydrate exploitation with in-situ catalytic oxidation thermochemistry as claimed in claim 6, it is characterized in that: described catalytic oxidation combustion device (14) is a coaxial sleeve reactor, pipe (18) tube side is the catalytic oxidation combustion district in the catalytic oxidation combustion device, shell side in the catalytic oxidation combustion device between pipe (18) and the outer layer sleeve is divided into two sections separate portions, wherein one section is burner preheating section (24), another section is burner heat exchanging segment (26), described fuel tank (8) is connected to burner preheating section (24) by pipeline, decomposition accelerating agent storage tank (9) and thermophore storage tank (10) are connected to burner heat exchanging segment (26) by pipeline, and catalytic oxidation combustion device inlet tube (23) connects pipe (18) in burner preheating section (24) and the catalytic oxidation combustion device; Pipe (18) is fixed on by many interior pipes and forms shell and tube reactor on the tube sheet in the described catalytic oxidation combustion device, and catalyst cupport is on the reactor inner tubal wall; Catalytic combustion product outlet (27) is communicated with pipe (18) in the catalytic oxidation combustion device, and decomposition accelerating agent and heat transport fluid outlet (19) are communicated with outer tube.

8. as the device of claim 6 or 7 described natural gas hydrate exploitation with in-situ catalytic oxidation thermochemistry, it is characterized in that: pipe (18) is finned tube in the described catalytic oxidation combustion device.

9. as the device of claim 6 or 7 described natural gas hydrate exploitation with in-situ catalytic oxidation thermochemistry, it is characterized in that: described catalytic combustion product outlet (27) is provided with check device (16).

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