The search for oil 2 探寻石油

The geologist needs to know what rocks the drill has reached, so every so often a sample is obtained with a coring bit. It cuts a clean cylinder of rock, from which can be seen the strata the drill has been cutting through. Once we get down to the oil, it usually flows to the surface because great pressure, either from or water, is pushing it. This pressure must be under control, and we control it by means of the mud which we circulate down the drill pipe. We endeavour to avoid the old, romantic idea of a gusher, which wastes oil and gas. We want it to stay down the hole until we can lead it off in a controlled manner.
地质学家需要知道钻头已以到达什么样的岩层，因此时常要用芯钻头取样。这种钻头能切割一段光滑的圆柱形岩石，从中能看出所钻透的地层。一旦到达油层，石油就会由于地下巨大的压力流到地面上来，这种巨大的压力来自地下天然气或水。这种压力必须加以控制，我们让泥桨顺着钻杆向下循环，用这种方法来控制压力。我们尽量避免使用陈旧天真的喷井方法，那样会浪费石油和天然气。我们要让石油留在井下，直到我们能用一种有控制的方法把它引上来为止。

New words and expressions 生词和短语

geologist
n. 地质学家
coring
取芯钻头
cylinder
n. 圆柱体
strata
n. 岩层[复]([单]stratum或strata [误用])
circulate
v. 注入，环流
gusher
n. 喷油井