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托福阅读文章解析：石油的起源

2017-09-27 10:00:32来源：网络

　　为了帮助考生对托福阅读考试内容更加熟悉，在考试中取得更加理想的成绩，新东方在线托福网为大家带来托福阅读文章解析：石油的起源一文，希望对大家备考冲刺有所帮助。更多精彩尽请关注新东方在线托福网!

　　The Origin of Petroleum 石油的起源

　　先读标题，进行预先分析

　　1. 地质类说明文

　　2. 石油的定义，地点，起源于何物，形成的过程，以及现存数量。

　　一、拆分段落并提炼信息。

　　Petroleum is defined as a gaseous, liquid, and semisolid naturally occurring substance that consists chiefly of hydrocarbons (chemical compounds of carbon and hydrogen). Petroleum is therefore a term that includes both oil and natural gas. Petroleum is nearly always found in marine sedimentary rocks. In the ocean, microscopic phytoplankton (tiny floating plants) and bacteria(simple, single-celled organisms) are the principal sources of organic matter that is trapped and buried in sediment. Most of the organic matter is buried in clay that is slowly converted to a fine-grained sedimentary rock known as shale. During this conversion, organic compounds are transformed to oil and natural gas.

　　第一段：石油的定义和存在地点，及有机物的转变

　　Part1：石油的定义特征，石油这个术语指的是油和天然气。

　　Part2：石油主要在海洋沉积岩中发现，微生物和细菌是有机物的主要来源，有机物最终转化成油和天然气。

　　Sampling on the continental shelves and along the base of the continental slopes has shown that fine muds beneath the seafloor contain up to 8 percent organic matter. Two additional kinds of evidencesupport the hypothesis that petroleum is a product of the decomposition of organic matter: oil possesses optical properties known only in hydrocarbons derived from organic matter, and oil contains nitrogen and certaincompounds believed to originate only in living matter. Acomplex sequence ofchemical reactions is involved in converting the original solid organic matter to oil and gas, andadditional chemical changes may occur in the oil and gas even after they have formed.

　　第二段：石油是有机物的产物

　　Part1：样本表明海底的泥包含8%的有机物。

　　Part2：两个额外的证据也表明了石油是有机物分解后的产物这一说法。

　　Part3：固体有机物转化成油和气是一个系列复杂的化学反应过程。

　　It is now well established that petroleum migrates through aquifers and can become trapped in reservoirs.Petroleum migration is analogous to groundwater migration. When oil and gas are squeezed out of the shale in which they originated and enter a body of sandstone or limestone somewhere above, they migrate readily because sandstones (consisting of quartz grains) and limestones (consisting of carbonate minerals) are much more permeable than any shale. The force of molecular attractionbetween oil and quartz or carbonate minerals is weaker than that between water and quartz or carbonate minerals. Hence, because oil and water do not mix, water remains fastened to the quartz or carbonate grains, while oil occupies the central parts of the larger openings in the porous sandstone or limestone. Because oil is lighter than water, it tends to glide upward past the carbonate- and quartz-held water. In this way, oil becomes segregated from the water; when it encounters a trap, it can form a pool.

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