【摘要】：隨著水平鉆井和水壓裂技術(shù)的應(yīng)用和發(fā)展,頁巖油、頁巖氣已成為可有效開發(fā)的非常規(guī)石油天然氣資源,其資源潛力巨大,是未來重要的替代能源,但目前頁巖油氣開發(fā)系數(shù)很低,僅為5%-10%。富有機(jī)質(zhì)泥頁巖中微米一納米級(jí)孔隙發(fā)育,為油氣的保存和運(yùn)移提供了空間和通道,因此,泥頁巖孔隙連通性研究是提高頁巖油氣采收率的關(guān)鍵問題之一。本文采用巖石小柱體吸水實(shí)驗(yàn)方法,將巖石柱體置于恒定溫度和濕度的條件下,通過稱重獲得巖石吸水量,并結(jié)合N2吸附法對(duì)孔隙結(jié)構(gòu)和BET比表面積的測量,以及TOC和粘土礦物含量的分析等,研究了巖石在不同濕度條件下對(duì)水的吸收程度,以此來探討孔隙連通性特征和影響泥頁巖吸水的主控因素。初步研究結(jié)果表明：(1)泥巖的飽和吸水量與TOC、粘土礦物含量呈現(xiàn)很好的線性關(guān)系,吸水量隨樣品TOC和粘土礦物含量的增加而增大,說明TOC和粘土礦物含量是影響泥頁巖吸水性的主控因素。(2)巖石飽和吸水量與其BET比表面積也呈現(xiàn)正相關(guān)性,同時(shí)吸水過程自發(fā)且可逆,巖石吸水過程為物理吸附,連通的孔隙增加了巖石的比表面積,為巖石吸水提供了場所。石柱地區(qū)龍馬溪組泥頁巖的飽和絕對(duì)吸水量與樣品體積呈線性正相關(guān),由斜率計(jì)算樣品有效孔隙度為6.23%,柱體樣品未經(jīng)破碎,較N2吸附法測量孔隙度值(9.09%)更加接近真實(shí)值。(3)垂直層面方向鉆取的柱體吸水結(jié)果與平行層面方向柱體相比,吸水趨勢更接近一致,達(dá)到平衡吸水所需時(shí)間前者較后者長,同時(shí),蠟封柱體(底面和周面蠟封,僅暴露頂面)吸水達(dá)平衡所需時(shí)間(360小時(shí))遠(yuǎn)大于未蠟封樣品(32小時(shí)),飽和吸水量相差較小,分別為9.28mg/g巖石、10.99mg/g巖石,表明泥頁巖垂直層面方向滲透性較平行層面方向差,其差異性可通過蠟封柱體吸水實(shí)驗(yàn)進(jìn)行量化。(4)泥頁巖的吸水過程滿足一級(jí)動(dòng)力學(xué)方程,通過模型可以對(duì)地下巖石的吸水隨時(shí)間的變化進(jìn)行模擬和預(yù)測,從而為研究壓裂液在巖石中的滲透、孔隙結(jié)構(gòu)和礦物組成對(duì)頁巖氣后期開采的影響提供實(shí)驗(yàn)手段和研究新思路。
[Abstract]:With the application and development of horizontal drilling and water fracturing technology, shale oil and shale gas have become unconventional oil and gas resources that can be effectively exploited. But at present shale oil and gas development coefficient is very low, only 5-10. The development of micron-nanometer pores in organic shale provides space and channel for the preservation and migration of oil and gas. Therefore, the study of pore connectivity is one of the key problems to improve the oil and gas recovery of shale. In this paper, the water absorption of rock is obtained by weighing the rock column under constant temperature and humidity, and the pore structure and BET specific surface area are measured by N2 adsorption method. The water absorption degree of rock under different moisture conditions was studied by TOC and clay mineral analysis. The characteristics of pore connectivity and the main controlling factors affecting shale water absorption were discussed. The preliminary results show that: (1) the saturated water absorption of mudstone has a good linear relationship with the TOC, clay mineral content, and the water absorption increases with the increase of TOC and clay mineral content. It is concluded that TOC and clay mineral content are the main controlling factors affecting the water absorption of shale. (2) the saturated water absorption of rock is positively correlated with its BET specific surface area, and the water absorption process is spontaneous and reversible, and the water absorption process of rock is physical adsorption. The connected pores increase the specific surface area of the rock and provide a place for the rock to absorb water. The saturated absolute water absorption of the shale of Longmaxi formation in Shizhu area shows a linear positive correlation with the sample volume. The effective porosity of the sample calculated by slope is 6.23, and the column sample is not broken. Compared with the N _ 2 adsorption method, the measured porosity value (9.09%) is closer to the true value. (3) the water absorption trend of the drilled cylinder in the vertical plane is closer to the same as that of the parallel plane cylinder. At the same time, the water absorption time of the wax seal cylinder (bottom and circumference wax seal, only exposed top surface) is much longer than that of the unwaxed sample (32 hours), and the difference of saturated water absorption is small, and the water absorption time of the wax seal cylinder (bottom and circumferential surface wax seal, only exposed top surface) is much longer (360 hours) than that of unwaxed seal sample (32 hours). 9.28mg/g rock and 10.99mg/g rock show that the permeability of shale in vertical direction is worse than that in parallel plane. The difference can be quantified by wax seal column water absorption experiment. (4) the water absorption process of shale meets the first-order dynamic equation, and the model can be used to simulate and predict the water absorption of underground rock with time. Therefore, this paper provides experimental means and new ideas for studying the influence of fracturing fluid permeability, pore structure and mineral composition on shale gas production.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：P618.13

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