本文選題：天然氣水合物　切入點(diǎn)：分解特性　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

【摘要】：天然氣水合物是一種固態(tài)的、非化學(xué)計(jì)量的、束縛有氣體分子的籠型冰狀晶體化合物,主要分布于凍土與海洋沉積物中的高壓低溫區(qū)域,其巨大的儲(chǔ)量被認(rèn)為是未來(lái)潛在能源。鑒于目前不同水合物儲(chǔ)藏開(kāi)采的可行性以及經(jīng)濟(jì)性問(wèn)題,降壓開(kāi)采被認(rèn)為是水合物三種開(kāi)采方法中最有效率的,且可以聯(lián)合其他開(kāi)采技術(shù)同時(shí)使用,因此研究沉積物中水合物降壓開(kāi)采過(guò)程的分解特性對(duì)于水合物儲(chǔ)藏的利用具有重大意義。本文實(shí)驗(yàn)研究了產(chǎn)氣壓力和多孔介質(zhì)導(dǎo)熱系數(shù)對(duì)甲烷水合物降壓分解特性的影響,分析了水合物二次生成和結(jié)冰現(xiàn)象的誘因,最后從儲(chǔ)層顯熱和外圍傳熱兩方面討論了傳熱因素對(duì)水合物降壓分解的影響。研究表明,產(chǎn)氣壓力的降低以及儲(chǔ)層導(dǎo)熱系數(shù)的增大能夠有效提高水合物的分解速率,水合物的整個(gè)降壓產(chǎn)氣過(guò)程可以分為三個(gè)階段：自由氣的排出、儲(chǔ)層顯熱的消耗、以及外圍傳熱驅(qū)動(dòng)下的水合物分解階段。第一階段,儲(chǔ)層中自由氣開(kāi)始產(chǎn)出,但甲烷水合物仍未分解；第二階段,儲(chǔ)層中水合物沿著相平衡線整體同時(shí)分解,水合物分解所需熱量主要來(lái)自?xún)?chǔ)層顯熱,而在第三階段,儲(chǔ)層壓力降至產(chǎn)氣壓力,水合物分解則轉(zhuǎn)變?yōu)橥鈬鷤鳠嶙饔孟碌挠赏庀騼?nèi)分解。由于儲(chǔ)層顯熱和外圍傳熱的不足,水合物二次生成和結(jié)冰現(xiàn)象常出現(xiàn)在儲(chǔ)層內(nèi)部靠近產(chǎn)氣井的區(qū)域,但在高導(dǎo)熱系數(shù)儲(chǔ)層中并未發(fā)生。此外,本文還引入了斯特藩數(shù)(Ste)和水合物分解速率常數(shù)(Kd)來(lái)研究?jī)?chǔ)層顯熱和外圍傳熱的對(duì)水合物降壓分解的影響,結(jié)果表明兩個(gè)傳熱因素是水合物降壓分解的主要驅(qū)動(dòng)力,但兩者大小均取決于水合物儲(chǔ)層的產(chǎn)氣壓力。同時(shí),本文還建立了水合物降壓分解的數(shù)值模型,在Darcy定律中考慮了重力項(xiàng)對(duì)氣水兩相滲流速度的影響,通過(guò)與本文實(shí)驗(yàn)結(jié)果的對(duì)比,驗(yàn)證了該模型的準(zhǔn)確性,并分析了降壓產(chǎn)氣過(guò)程中儲(chǔ)層壓力、溫度以及水合物飽和度的分布。研究表明,外部傳熱主要經(jīng)儲(chǔ)層側(cè)面和下蓋層傳入儲(chǔ)層內(nèi)部,并證明了水合物由初期的空間整體分解轉(zhuǎn)變?yōu)橥獠總鳠嶂鲗?dǎo)的由外向內(nèi)分解的過(guò)程。
[Abstract]:Natural gas hydrate is a solid, non-stoichiometric, gaseous molecules bound cage ice crystal compounds, mainly distributed in frozen soil and marine sediments in the high-pressure low-temperature region, Its huge reserves are considered to be potential sources of energy in the future. Given the feasibility and economy of exploiting different hydrate reserves, depressurized extraction is considered to be the most efficient of the three methods of hydrate extraction. And can be used in conjunction with other mining technologies, Therefore, it is of great significance to study the decomposing characteristics of hydrate depressurization in sediments. The effects of gas production pressure and thermal conductivity of porous media on the decomposing characteristics of methane hydrate are experimentally studied in this paper. The inducement of hydrate secondary formation and ice formation is analyzed. Finally, the influence of heat transfer factors on hydrate decomposing is discussed from two aspects of reservoir sensible heat transfer and peripheral heat transfer. The reduction of gas production pressure and the increase of reservoir thermal conductivity can effectively increase the decomposition rate of hydrate. The whole process of reducing pressure and producing gas of hydrate can be divided into three stages: the discharge of free gas and the consumption of sensible heat in reservoir. In the first stage, the free gas in the reservoir begins to produce, but the methane hydrate is not decomposed, in the second stage, the hydrate in the reservoir is decomposed simultaneously along the phase equilibrium line. The heat needed for hydrate decomposition mainly comes from the sensible heat in the reservoir. In the third stage, the reservoir pressure drops to the gas production pressure, and the hydrate decomposition is transformed into the outer to inner decomposition under the action of the peripheral heat transfer, because of the deficiency of the reservoir sensible heat and the peripheral heat transfer. The secondary formation and ice formation of hydrate often occur in the area near the gas-producing well inside the reservoir, but not in the reservoir with high thermal conductivity. In this paper, Stean and Kd) are introduced to study the effect of reservoir sensible heat and peripheral heat transfer on hydrate decomposing. The results show that two heat transfer factors are the main driving forces of hydrate decomposing. But both of them depend on the gas production pressure of hydrate reservoir. At the same time, a numerical model of gas hydrate decomposing is established, and the influence of gravity term on gas-water two-phase percolation velocity is considered in Darcy's law. The accuracy of the model is verified by comparing with the experimental results in this paper, and the distribution of reservoir pressure, temperature and hydrate saturation in the process of reducing pressure and gas production is analyzed. The external heat transfer is mainly transmitted to the reservoir interior through the lateral and lower caprock layers, and it is proved that the hydrate has changed from the space integral decomposition in the initial stage to the outer to internal decomposition process dominated by the external heat transfer.
【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

【共引文獻(xiàn)】

相關(guān)期刊論文 前5條

1 張學(xué)民;李金平;吳青柏;王春龍;南軍虎;;CO_2置換天然氣水合物中CH_4的研究進(jìn)展[J];過(guò)程工程學(xué)報(bào);2014年04期

2 張學(xué)民;李金平;吳青柏;南軍虎;焦亮;;CO_2置換開(kāi)采凍土區(qū)天然氣水合物中CH_4的可行性研究[J];化工進(jìn)展;2014年S1期

3 劉樂(lè)樂(lè);魯曉兵;張旭輝;;天然氣水合物分解引起多孔介質(zhì)變形流固耦合研究[J];天然氣地球科學(xué);2013年05期

4 劉樂(lè)樂(lè);魯曉兵;張旭輝;;降壓開(kāi)采模擬試驗(yàn)的水合物分解陣面演化過(guò)程[J];實(shí)驗(yàn)力學(xué);2015年04期

5 Jun Chen;Yan-Hong Wang;Xue-Mei Lang;Shuan-Shi Fan;;Energy-efficient methods for production methane from natural gas hydrates[J];Journal of Energy Chemistry;2015年05期

相關(guān)博士學(xué)位論文 前3條

1 楊圣文;天然氣水合物開(kāi)采模擬與能效分析[D];華南理工大學(xué);2013年

2 李洋輝;天然氣水合物沉積物強(qiáng)度及變形特性研究[D];大連理工大學(xué);2013年

3 石定賢;多孔介質(zhì)天然氣水合物開(kāi)采的基礎(chǔ)研究[D];太原理工大學(xué);2014年

相關(guān)碩士學(xué)位論文 前4條

1 李杰;天然氣水合物注熱、降壓開(kāi)采可行性實(shí)驗(yàn)研究[D];中國(guó)石油大學(xué)（華東）;2013年

2 劉笛;多孔介質(zhì)中天然氣水合物分解過(guò)程傳熱分析[D];大連理工大學(xué);2014年

3 馬小晶;儲(chǔ)層物性對(duì)甲烷水合物分解影響的模型研究[D];大連理工大學(xué);2014年

4 郝天翔;應(yīng)用FLUENT數(shù)值模擬天然氣水合物開(kāi)采過(guò)程[D];吉林大學(xué);2015年

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本文編號(hào)：1650416