發(fā)布時(shí)間：2018-01-06 09:43

  本文關(guān)鍵詞：氣體水合物沉積物力學(xué)特性研究　出處：《大連理工大學(xué)》2015年碩士論文　論文類(lèi)型：學(xué)位論文

  更多相關(guān)文章： 水合物沉積物 CO_2置換開(kāi)采 力學(xué)特性 CT

【摘要】：天然氣水合物因儲(chǔ)量大、清潔無(wú)污染等優(yōu)點(diǎn),成為世界范圍廣泛關(guān)注、研究的新型能源。中國(guó)青藏高原、祁連山凍土帶及大興安嶺等地區(qū)存在大量?jī)鐾羺^(qū)水合物。C02置換法在開(kāi)采天然氣同時(shí)可以封存C02,被認(rèn)為是一種很有前景的開(kāi)采方式,且在凍土區(qū)具有可行性。然而,天然氣水合物的開(kāi)采可能導(dǎo)致儲(chǔ)層結(jié)構(gòu)的失穩(wěn),進(jìn)而引起如鉆井坍塌、海底滑坡等地質(zhì)災(zāi)害,及溫室效應(yīng)等氣候?yàn)?zāi)害。因此在天然氣水合物的商業(yè)開(kāi)采前,必須研究水合物沉積物的強(qiáng)度和變形特性,及水合物開(kāi)采對(duì)礦藏沉積層力學(xué)特性的影響。本文針對(duì)凍土區(qū)CO2置換開(kāi)采法,開(kāi)采過(guò)程中及開(kāi)采后沉積物的力學(xué)特性進(jìn)行研究。本研究利用大連理工大學(xué)自行研制的TAW-60型低溫高壓三軸儀,研究了二氧化碳水合物體積分?jǐn)?shù)、圍壓對(duì)CH4、CO2混合水合物沉積物強(qiáng)度和變形特性的影響,建立了水合物沉積物破壞強(qiáng)度σm與二氧化碳水合物體積分?jǐn)?shù)a、圍壓σ3的變化關(guān)系式,及粘聚力c與二氧化碳水合物體積分?jǐn)?shù)α的關(guān)系式。結(jié)果表明：試樣破壞過(guò)程可分為彈性變形、應(yīng)變硬化、試樣屈服三階段；不同圍壓下,試樣最大偏應(yīng)力都隨二氧化碳水合物體積分?jǐn)?shù)的增加呈線(xiàn)性增大；5MPa以下,試樣最大偏應(yīng)力隨圍壓的增加而增大；5MPa以上,試樣最大偏應(yīng)力隨圍壓的增加而減��；試樣粘聚力隨二氧化碳水合物體積分?jǐn)?shù)的增加近似線(xiàn)性增大,內(nèi)摩擦角則變化不大且數(shù)值較小,粘聚力對(duì)試樣抗剪強(qiáng)度起主導(dǎo)作用。此外,研究了圍壓對(duì)二氧化碳水合物沉積物蠕變特性的影響,建立了與溫度、孔隙度、蠕變加載系數(shù)等實(shí)驗(yàn)參數(shù)關(guān)聯(lián)的流變起始時(shí)間及流變速率計(jì)算公式。結(jié)果表明：試樣的蠕變曲線(xiàn)呈現(xiàn)對(duì)數(shù)形,顯示出明顯的衰減蠕變特征；試樣流變起始時(shí)間、流變起始應(yīng)變和穩(wěn)態(tài)蠕變速率隨圍壓增大呈指數(shù)型減��；圍壓的增大,導(dǎo)致試樣抵抗蠕變能力的增強(qiáng),在低圍壓條件時(shí)尤為明顯,高圍壓下影響趨于微弱。最后,利用島津公司生產(chǎn)的inspeXio SMX-225CT型微焦點(diǎn)X射線(xiàn)CT系統(tǒng),首次研究了不同三軸壓縮階段下,甲烷水合物沉積物試樣細(xì)觀結(jié)構(gòu)演變過(guò)程。結(jié)果表明：試樣5%應(yīng)變以前主要為彈性變形,內(nèi)部水合物形態(tài)、分布變化不大,膠結(jié)結(jié)構(gòu)完整,卸荷后高度回彈；5%-15%應(yīng)變過(guò)程主要為塑性變形,試樣中部向外隆起,內(nèi)部存在水合物的變形破碎、顆粒的遷移；15%應(yīng)變時(shí),試樣內(nèi)部密度小于外部,整體呈剪漲趨勢(shì),且內(nèi)部孔隙發(fā)育較差,未出現(xiàn)明顯斷裂帶。
[Abstract]:Because of its large reserves, clean and pollution-free, natural gas hydrate has become a new type of energy, which is widely concerned and studied in the world, and the Qinghai-Tibet Plateau of China. There are a large number of permafrost hydrate. C02 replacement method in the Qilian Mountains and Daxing'an Mountains, which can seal C02 while exploiting natural gas, which is considered to be a promising mining method. However, the exploitation of natural gas hydrate may lead to instability of reservoir structure, which may lead to geological disasters such as drilling collapse, submarine landslide and so on. Therefore, before commercial exploitation of natural gas hydrate, it is necessary to study the strength and deformation characteristics of hydrate sediments. And the effect of hydrate mining on the mechanical properties of deposit deposits. This paper aims at the CO2 displacement mining method in permafrost region. The mechanical properties of sediments during and after mining were studied. The volume fraction of carbon dioxide hydrate was studied by using TAW-60 model low temperature and high pressure triaxial instrument developed by Dalian University of Technology. The effect of confining pressure on the strength and deformation characteristics of CH4CO _ 2 mixed hydrate sediments is studied. The relationship between the destruction strength 蟽 _ m of hydrate sediments and the volume fraction a and 蟽 _ 3 of carbon dioxide hydrate is established. The results show that the failure process can be divided into three stages: elastic deformation, strain hardening and specimen yield. Under different confining pressures, the maximum deflection stress increases linearly with the increase of carbon dioxide hydrate volume fraction. Under 5 MPA, the maximum deflection stress increases with the increase of confining pressure. Above 5 MPA, the maximum deflection stress decreases with the increase of confining pressure. The cohesive force increases linearly with the increase of carbon dioxide hydrate volume fraction, but the internal friction angle changes little and the value is small. The cohesion force plays a leading role in the shear strength of the sample. The influence of confining pressure on creep characteristics of carbon dioxide hydrate sediments was studied. The formula for calculating rheological initiation time and rheological rate associated with experimental parameters such as creep loading coefficient, etc. The results show that the creep curve of the specimen shows logarithmic shape, showing obvious attenuation creep characteristics. The initial rheological strain and steady creep rate decrease exponentially with the increase of confining pressure. The increase of confining pressure leads to the enhancement of the creep resistance of the specimen, especially under low confining pressure, and the influence of high confining pressure tends to be weak. Finally. Using the inspeXio SMX-225CT microfocus X-ray CT system produced by Shimadzu Company, the different triaxial compression stages were studied for the first time. The results show that the strain of sample 5% was mainly elastic deformation, the shape of hydrate in the sample changed little, the cemented structure was intact, and the rebound was high after unloading. The strain process of 5- 15% is mainly plastic deformation, the central part of the specimen is uplifted outwards, the hydrate is deformed and broken, and the particles migrate. When the strain is 15%, the internal density of the specimen is smaller than that of the outside, and the whole specimen is shearing up, and the internal porosity is poor, and there is no obvious fault zone.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TE311

【參考文獻(xiàn)】

相關(guān)期刊論文 前2條

1 宋永臣;阮徐可;梁海峰;李清平;趙越超;;天然氣水合物熱開(kāi)采技術(shù)研究進(jìn)展[J];過(guò)程工程學(xué)報(bào);2009年05期

2 吳青柏;蔣觀利;張鵬;鄧友生;楊玉忠;侯彥東;張寶貴;;青藏高原昆侖山埡口盆地發(fā)現(xiàn)天然氣水合物賦存的證據(jù)[J];科學(xué)通報(bào);2015年01期

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本文編號(hào)：1387354