问题 问答题 简答题

钻压对金刚石钻进中有何影响?

答案

参考答案:

根据实践经验,每一个金刚石钻头的整个使用过程大体上可分为初磨阶段和一般钻进阶段,在不同的阶段应采用不同的钻压。

(1)初压力:金刚石钻头初次下至孔底时所给的压力为初压力。由于新钻头的金刚石出刃不一致,以及钻头外径与孔壁之间、内径与岩芯根底之间不一定相适应。因此应采用小钻压、慢转速磨一段时间,以免发生金刚石崩刃、胎体掉块或岩芯堵塞。

(2)一般钻进压力:在新钻头适应孔底环境之后,可逐渐加大钻压,同时转速也应加快,使其保持较高的钻进效率。当金刚石逐渐磨钝,效率有下降的趋热时,为了保持原有效率,则可继续加大钻压,一直到钻头停用为止。这一过程的钻压就叫一般钻进压力。

金刚石的抗压能力虽然比任何岩石的都大的多,但是由于目前钻具(主要是钻杆)还不十分稳定,如果无止境地加压,就将造成金刚石的碎裂。根据实践经验,每一个金刚石钻头的整个使用过程大体上可分为初磨阶段和一般钻进阶段,在不同的阶段应采用不同的钻压。

(1)初压力:金刚石钻头初次下至孔底时所给的压力为初压力。由于新钻头的金刚石出刃不一致,以及钻头外径与孔壁之间、内径与岩芯根底之间不一定相适应。因此应采用小钻压、慢转速磨一段时间,以免发生金刚石崩刃、胎体掉块或岩芯堵塞。

(2)一般钻进压力:在新钻头适应孔底环境之后,可逐渐加大钻压,同时转速也应加快,使其保持较高的钻进效率。当金刚石逐渐磨钝,效率有下降的趋热时,为了保持原有效率,则可继续加大钻压,一直到钻头停用为止。这一过程的钻压就叫一般钻进压力。

金刚石的抗压能力虽然比任何岩石的都大的多,但是由于目前钻具(主要是钻杆)还不十分稳定,如果无止境地加压,就将造成金刚石的碎裂。

单项选择题
阅读理解

阅读理解。

    One of the most famous scientists to study adaptations (适应能力) was Charles Darwin (达尔文). He was

born in England in 1809. He wasn't the best student in his school, but when he was 16,his father sent him to

a medical school. Charles liked spending time outdoors observing (观察) nature more than attending medical

classes and dropped out without graduating.

    Next, Charles'father sent him to school to become a minister (牧师). This time he made it to graduation,

But he didn't want to do the work of a minister. His friends encouraged him to follow his interest in science.

    After graduation, Charles was invited to sail on the Beagle as an unpaid scientist. He wasn't the first choice,

but he was the lucky one to go. The Beagle was to travel to South America and then around the world. The

crew's task was to make maps of the places they visited.

    On December 27th, 1831 Charles Darwin sailed from England on the Beagle. The trip was planned to last

two years. In fact, it lasted five. During this time, he saw many amazing things. He collected lots of plants

and animals and took them back to England to study.

    Twenty-three years later, Darwin published an scientific paper with another man named Wallace. Darwin

described how some animals have adaptations that help them survive. They are passed on to offspring (后代).

Darwin's ideas about adaptations to the study of living things.

1. Darwin was very interested in _____. [ ]

A. attending medical classes

B. the work of a minister

C. sailing around the world

D. science

2. The Beagle was a(an) _____. [ ]

A. ship

B. plane

C. plant

D. animal

3. When Darwin published the scientific paper, he was _____ years old. [ ]

A. twenty-three

B. twenty-two

C. forty-five 

D. fifty

4. The underlined word"they" in the last paragraph refers to (指的是) _____. [ ]

A. adaptations

B. Darwin and Wallace

C. animals

D. Darwin's ideas

5. Which of the following is true? [ ]

A. Darwin graduated from a medical school.

B. Some animals have adaptations so that they can survive.

C. Darwin published a scientific paper by himself.

D. Darwin was first chosen to sail on the Beagle.