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of boreholes into the earth. Often used while
drilling oil and naturalgas wellsand
onexploration drilling rigs
3 packer c a cutting tool used to create cylindrical holes,
almost always of circular cross-section
4 drilling mud d a technique of conveying well logging tools into
the well borehole downhole as part of the bottom
hole assembly

5 Logging While e the broken bits of solid material removed from
Drilling a borehole drilled by rotary, percussion, or auger
methods
6 drill pipe f the practice of making a detailed record (a well
log) of the geologic formations penetrated by a
borehole
7 rig g a cylindrical section of (usually) a naturally
occurring substance which is obtained by drilling
with special drills into the substance, for example
sediment or rock, with a hollow steel tube called
a core drill
8 well logging h hollow, thick-walled, steel piping that is used on
drilling rigs and horizontal drilling to facilitate
the drilling of a wellbore
9 drill string i a machine which creates holes in the ground

10 core sample j a standard component of the completion
hardware of oil or gas wells used to provide a
seal between the outside of the production tubing
and the inside of the casing, liner, or wellbore
wall

Pre-reading and while-reading tasks

3 Scan the text and answer the following questions.
− What is formation evaluation?
− What are the responsibilities of an operator?
− What kinds of well logging are available?
− What are the main functions of logging while drilling tools?

Determining whether a formation contains oil and gas falls under the realm of
formation evaluation. Formation evaluation includes the activities the operator does
to test a formation for hydrocarbons. The operator must not only know whether
hydrocarbons exist, but also whether they exist in ample amounts. A hole may
penetrate a formation that contains hydrocarbons; however, if the formation does not
contain enough hydrocarbons for the operating company to get its monetary
investment back, the company may declare the hole to be dry. Methods of formation

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