柴達木盆地東部石炭系頁巖納米級孔隙特征研究
發(fā)布時間：2018-09-14 19:53
【摘要】：頁巖氣是一種自生自儲于頁巖孔隙中的清潔能源,隨著社會對能源需求量的增加,世界各國越來越重視對頁巖氣的研究和開采。中國對頁巖的研究及開采要落后于發(fā)達國家,尤其對頁巖微觀結構觀測及頁巖氣滲流等方面研究仍處于起步階段。微觀孔隙是頁巖孔隙網(wǎng)絡組成中數(shù)量最多的的孔隙類型,查明其結構特征及其對頁巖氣滲流的影響對頁巖氣開采至關重要。柴達木盆地是目前國內證實具有頁巖氣開采潛力的盆地之一,選取盆地東部石灰溝地區(qū)zk1-1井及石淺井的石炭系克魯克組頁巖展開研究。采用實驗室內FESEM二次成像技術,觀察頁巖樣品新鮮斷面及氬離子拋光后的微觀結構。證實研究區(qū)頁巖存在基質內孔、礦物顆粒晶間孔、溶蝕孔、有機質內孔及微裂縫五種孔隙類型。利用壓汞法及氣體吸附法分別測定頁巖宏孔、介孔及微孔的孔徑分布,得出頁巖平均孔徑為4nm-6nm左右,孔隙度在0.86%-5.48%之間。觀察孔隙分布范圍從幾納米紙幾微米不等,孔隙特征與美國Barnett頁巖及四川盆地龍馬溪組頁巖相近似,可以作為頁巖氣儲集及運移的空間通道。根據(jù)國家相關的標準,測定研究區(qū)樣品的孔隙度、礦物成分、TOC、成熟度(R0)及干酪根類型等地化性質。結果表明研究區(qū)頁巖礦物成分主要包括碎屑礦物、黏土礦物及碳酸鹽礦物;干酪根類型主要為II型;成熟度1.32-2.05之間,屬于中等水平;TOC較低,但達到最低產氣要求。表明柴達木盆地石炭系為一套具有開發(fā)價值的烴源巖。為了得出孔隙特征的控制因素,分別作出其與頁巖孔容的相關關系圖。表明頁巖孔隙受礦物成分及孔隙度影響較大,而TOC、干酪根類型及成熟度與頁巖產氣能力關系密切。對于頁巖氣的滲流主要考慮了達西流、滑脫效應及克努森擴散三種流動方式。根據(jù)達西實驗的原理設計滲流實驗,得出實驗數(shù)據(jù)表明滲流能力與樣品孔徑呈正相關關系。結合質量通量模型和表觀滲透率公式計算得出滑脫因子、擴散系數(shù)及達西滲透率。結果表明納米孔中的滲流克努森擴散所占比例很小,在壓力小時以滑脫為主達西流次之,隨著壓力升高,達西流所占比例升高,并超過滑脫效應。
[Abstract]:Shale gas is a kind of clean energy which is self-generated and stored in shale pores. With the increasing demand for energy, more and more countries in the world attach importance to the research and exploitation of shale gas. The research and exploitation of shale in China lags behind that in developed countries, especially in the observation of shale microstructure and shale gas percolation. Micropore is the most abundant pore type in the shale pore network. It is very important to find out its structural characteristics and its influence on shale gas percolation. The Qaidam Basin is one of the basins with shale gas potential confirmed in China. The zk1-1 well and the Carboniferous Kruke formation shale in the Limegou area of the eastern part of the basin and the Carboniferous Kruke formation shale are studied. The fresh section of shale samples and the microstructure after argon ion polishing were observed by FESEM secondary imaging in laboratory. It is confirmed that there are five types of pores in shale in the study area: intergranular pore, dissolved pore, organic pore and microfracture. The pore size distribution of shale macropore, mesopore and micropore was determined by mercury injection method and gas adsorption method respectively. The average pore size of shale was about 4nm-6nm, and the porosity was between 0.86% and 5.48%. The pore distribution ranges from several nanometers to several microns. The pore characteristics are similar to those of the Barnett shale in the United States and the Longmaxi formation shale in Sichuan basin, which can be used as a space channel for shale gas storage and migration. According to the relevant national standards, the porosity, mineral composition, maturity (R0) and kerogen type of the samples in the study area were determined. The results show that the mineral composition of shale in the study area is mainly composed of clastic minerals, clay minerals and carbonate minerals, the kerogen type is mainly II type, and the maturity is between 1.32 and 2.05, which belongs to the low level of II, but meets the minimum gas production requirements. It shows that Carboniferous in Qaidam Basin is a set of source rocks with development value. In order to obtain the controlling factors of pore characteristics, the correlation diagrams between porosity and shale pore volume were made. The results show that the porosity of shale is greatly affected by mineral composition and porosity, while the type and maturity of TOC, kerogen are closely related to the gas production capacity of shale. For shale gas seepage, Darcy flow, slip effect and Knudsen diffusion are considered. According to the principle of Darcy experiment, the seepage experiment is designed, and the experimental data show that the percolation ability is positively related to the pore size of the sample. The slip factor, diffusion coefficient and Darcy permeability are calculated by combining mass flux model and apparent permeability formula. The results show that the percentage of percolation and Knudsen diffusion in the nano-pore is very small. In the pressure hour, the slip flow is the second. With the increase of the pressure, the proportion of the Darcy flow increases and exceeds the slippage effect.
【學位授予單位】：中國地質大學(北京)
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TE31
本文編號：2243710
[Abstract]:Shale gas is a kind of clean energy which is self-generated and stored in shale pores. With the increasing demand for energy, more and more countries in the world attach importance to the research and exploitation of shale gas. The research and exploitation of shale in China lags behind that in developed countries, especially in the observation of shale microstructure and shale gas percolation. Micropore is the most abundant pore type in the shale pore network. It is very important to find out its structural characteristics and its influence on shale gas percolation. The Qaidam Basin is one of the basins with shale gas potential confirmed in China. The zk1-1 well and the Carboniferous Kruke formation shale in the Limegou area of the eastern part of the basin and the Carboniferous Kruke formation shale are studied. The fresh section of shale samples and the microstructure after argon ion polishing were observed by FESEM secondary imaging in laboratory. It is confirmed that there are five types of pores in shale in the study area: intergranular pore, dissolved pore, organic pore and microfracture. The pore size distribution of shale macropore, mesopore and micropore was determined by mercury injection method and gas adsorption method respectively. The average pore size of shale was about 4nm-6nm, and the porosity was between 0.86% and 5.48%. The pore distribution ranges from several nanometers to several microns. The pore characteristics are similar to those of the Barnett shale in the United States and the Longmaxi formation shale in Sichuan basin, which can be used as a space channel for shale gas storage and migration. According to the relevant national standards, the porosity, mineral composition, maturity (R0) and kerogen type of the samples in the study area were determined. The results show that the mineral composition of shale in the study area is mainly composed of clastic minerals, clay minerals and carbonate minerals, the kerogen type is mainly II type, and the maturity is between 1.32 and 2.05, which belongs to the low level of II, but meets the minimum gas production requirements. It shows that Carboniferous in Qaidam Basin is a set of source rocks with development value. In order to obtain the controlling factors of pore characteristics, the correlation diagrams between porosity and shale pore volume were made. The results show that the porosity of shale is greatly affected by mineral composition and porosity, while the type and maturity of TOC, kerogen are closely related to the gas production capacity of shale. For shale gas seepage, Darcy flow, slip effect and Knudsen diffusion are considered. According to the principle of Darcy experiment, the seepage experiment is designed, and the experimental data show that the percolation ability is positively related to the pore size of the sample. The slip factor, diffusion coefficient and Darcy permeability are calculated by combining mass flux model and apparent permeability formula. The results show that the percentage of percolation and Knudsen diffusion in the nano-pore is very small. In the pressure hour, the slip flow is the second. With the increase of the pressure, the proportion of the Darcy flow increases and exceeds the slippage effect.
【學位授予單位】：中國地質大學(北京)
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TE31
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