發(fā)布時間：2018-02-27 09:35

  本文關(guān)鍵詞： 硬脆性頁巖 水化作用 微觀結(jié)構(gòu) 坍塌壓力　出處：《西南石油大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：近年來,隨著我國對石油天然氣資源需求量的不斷增大,各大石油公司也加大了頁巖氣勘探開發(fā)的力度,然而硬脆性頁巖地層井壁穩(wěn)定性問題一直是制約深層油氣資源安全高效開發(fā)的技術(shù)瓶頸,特別是水化作用對硬脆性頁巖井壁穩(wěn)定的影響。因此,為了揭示硬脆性頁巖地層井壁失穩(wěn)的機理,選擇某研究工區(qū)硬脆性頁巖為研究對象開展室內(nèi)試驗研究,包括礦物組成、比表面積、潤濕性、陽離子交換容量、微觀結(jié)構(gòu)及三軸壓縮試驗,研究了浸泡鉆井液對研究工區(qū)硬脆性頁巖強度特性的影響。基于以上試驗得出硬脆性頁巖理化特性、力學(xué)特征,分析了由于頁巖本身性質(zhì)導(dǎo)致頁巖地層井壁失穩(wěn)的原因及水化作用對硬脆性頁巖井壁失穩(wěn)的影響。并基于頁巖力學(xué)特性以及井周應(yīng)力建立了研究工區(qū)目直井的坍塌壓力計算模型,分析了鉆井液浸泡時間對坍塌壓力的影響。研究結(jié)果表明： (1)研究工區(qū)目的層硬脆性頁巖以石英和黏土礦物為主,其中黏土礦物以伊利石和伊/蒙混層為主。硬脆性頁巖雖不含有蒙脫石,但伊/蒙混層含量比較高,其還是能表現(xiàn)出一定水化膨脹性； (2)通過潤濕性測試及比表面積測試發(fā)現(xiàn),頁巖的低比表面積和水濕性可知巖石是很容易發(fā)生水侵現(xiàn)象；同時通過電子電鏡掃描可看出,硬脆性頁巖微裂隙、微孔隙及層理發(fā)育,鉆井液濾液很容易沿著層理面以及微裂縫侵入到巖石內(nèi)部,加劇水化作用。而聲波測試也證明了鉆井液濾液改變了巖石內(nèi)部結(jié)構(gòu)。 (3)通過巖石力學(xué)實驗研究了水化作用對硬脆性巖石的強度、硬度等影響,結(jié)果表明水化作用將使硬脆性頁巖強度及硬度降低,其下降幅度隨著水化程度的加深而減小。 (4)根據(jù)浸泡巖石的三軸力學(xué)實驗得到的浸泡之后巖石強度參數(shù),,并通過對目標(biāo)地層頁巖物性、力學(xué)特性分析,建立直井井壁坍塌壓力計算模型,分析了水化作用對坍塌壓力的影響。 結(jié)合以上研究內(nèi)容發(fā)現(xiàn)硬脆性頁巖地層層理微裂縫、微裂隙發(fā)育,在鉆井液方面需要鉆井液具有較強的封堵性能以及失水控制能力。盡量避免水或其他液相沿裂縫或裂紋侵入,是該類地層鉆井液防塌的關(guān)鍵。
[Abstract]:In recent years, with the increasing demand for oil and natural gas resources in China, major oil companies have also increased the intensity of shale gas exploration and development. However, the problem of wellbore stability in hard and brittle shale formation has always been the technical bottleneck restricting the safe and efficient exploitation of deep oil and gas resources, especially the influence of hydration on the stability of hard brittle shale wellbore. In order to reveal the mechanism of wellbore instability in hard brittle shale formation, a laboratory study of hard brittle shale was carried out in a study area, including mineral composition, specific surface area, wettability and cation exchange capacity. The influence of immersion drilling fluid on the strength characteristics of hard brittle shale was studied by microstructure and triaxial compression test. Based on the above tests, the physical and chemical properties and mechanical characteristics of hard brittle shale were obtained. The cause of shale formation wall instability caused by shale itself and the influence of hydration on the instability of hard brittle shale shaft wall are analyzed. Based on the shale mechanical properties and the stress around the well, the collapse of the straight well in the research area is established. Collapse pressure calculation model, The influence of drilling fluid immersion time on collapse pressure is analyzed. 1) the hard brittle shale in the study area is mainly composed of quartz and clay minerals, and the clay minerals are mainly Illite and Illite / montmorillonite. Although the hard brittle shale does not contain montmorillonite, the content of Iraq / montmorillonite is relatively high. It can still show a certain hydration expansion; (2) through wettability test and specific surface area test, the low specific surface area and water wettability of shale show that the rock is easy to be invaded by water, at the same time, the micro-fracture, micropore and stratification of hard and brittle shale can be seen by scanning electron microscope. Drilling fluid filtrate can easily invade the rock along the stratigraphic surface and microfracture, and the hydration is aggravated. The sonic test also proves that the drilling fluid filtrate changes the internal structure of the rock. 3) the effect of hydration on the strength and hardness of hard brittle rock is studied by rock mechanics experiment. The results show that hydration will reduce the strength and hardness of hard brittle shale, and the decreasing range will decrease with the deepening of hydration degree. 4) according to the rock strength parameters obtained from the triaxial mechanical experiment of immersed rock, and through the analysis of the physical properties and mechanical properties of the target shale, a model for calculating the collapse pressure of the vertical well wall is established. The influence of hydration on collapse pressure was analyzed. Combined with the above research contents, it is found that the hard and brittle shale strata have microfractures and microfractures. It is necessary for drilling fluid to have strong plugging performance and water loss control ability in drilling fluid. It is the key to prevent sloughing of drilling fluid in this kind of formation to avoid water or other liquid phase intrusion along fracture or crack as far as possible.
【學(xué)位授予單位】：西南石油大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TE254

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