本文選題：天然氣水合物　切入點：分解特性　出處：《大連理工大學》2015年碩士論文　論文類型：學位論文

【摘要】：天然氣水合物是一種固態(tài)的、非化學計量的、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,其巨大的儲量被認為是未來潛在能源。鑒于目前不同水合物儲藏開采的可行性以及經(jīng)濟性問題,降壓開采被認為是水合物三種開采方法中最有效率的,且可以聯(lián)合其他開采技術同時使用,因此研究沉積物中水合物降壓開采過程的分解特性對于水合物儲藏的利用具有重大意義。本文實驗研究了產(chǎn)氣壓力和多孔介質(zhì)導熱系數(shù)對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,最后從儲層顯熱和外圍傳熱兩方面討論了傳熱因素對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層導熱系數(shù)的增大能夠有效提高水合物的分解速率,水合物的整個降壓產(chǎn)氣過程可以分為三個階段：自由氣的排出、儲層顯熱的消耗、以及外圍傳熱驅(qū)動下的水合物分解階段。第一階段,儲層中自由氣開始產(chǎn)出,但甲烷水合物仍未分解；第二階段,儲層中水合物沿著相平衡線整體同時分解,水合物分解所需熱量主要來自儲層顯熱,而在第三階段,儲層壓力降至產(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)在儲層內(nèi)部靠近產(chǎn)氣井的區(qū)域,但在高導熱系數(shù)儲層中并未發(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)來研究儲層顯熱和外圍傳熱的對水合物降壓分解的影響,結(jié)果表明兩個傳熱因素是水合物降壓分解的主要驅(qū)動力,但兩者大小均取決于水合物儲層的產(chǎn)氣壓力。同時,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對氣水兩相滲流速度的影響,通過與本文實驗結(jié)果的對比,驗證了該模型的準確性,并分析了降壓產(chǎn)氣過程中儲層壓力、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)儲層側(cè)面和下蓋層傳入儲層內(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У挠赏庀騼?nèi)分解的過程。
[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.
【學位授予單位】：大連理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TE311

【共引文獻】

相關期刊論文 前5條

1 張學民;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的研究進展[J];過程工程學報;2014年04期

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

3 劉樂樂;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;2013年05期

4 劉樂樂;魯曉兵;張旭輝;;降壓開采模擬試驗的水合物分解陣面演化過程[J];實驗力學;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

相關博士學位論文 前3條

1 楊圣文;天然氣水合物開采模擬與能效分析[D];華南理工大學;2013年

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

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

相關碩士學位論文 前4條

1 李杰;天然氣水合物注熱、降壓開采可行性實驗研究[D];中國石油大學（華東）;2013年

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

3 馬小晶;儲層物性對甲烷水合物分解影響的模型研究[D];大連理工大學;2014年

4 郝天翔;應用FLUENT數(shù)值模擬天然氣水合物開采過程[D];吉林大學;2015年

，

本文編號：1650416