Borehole Stratigraphy

Question 1

A well log derived from instruments in a sonde lowered down the borehole on flexible steel cable; e.g., resistivity, sonic gamma ray logs, etc.

Answer 1

Wireline log

Question 2

A cylindrical downhole logging tool that houses electrical and radioactivity measuring instruments

Answer 2

sonde

Question 3

Line drawn on a SP log through the maximum deflections for thick, clean sands, provided the salinity of the pore space water does not vary.

Answer 3

sand line

Question 4

Drilling method employing a drill bit at the bottom of a rotating drill pipe where the drill bit is lubricated and cooled, and the drill cuttings are brought to the surface by circulating drilling mud.

Answer 4

Rotary drilling

Question 5

well log that records the changing values of the resistance in the rock to an electric current sent into the ground by two electrodes.

Answer 5

Resistivity Log

Question 6

Line drawn through the minimum deflections marking impermeable shales on an SP log

Answer 6

Shale line

Question 7

Log of drilling mud and drill cuttings from rotary drilling

Answer 7

Mud Log

Question 8

Layer of drilling mud that becomes plastered to the wall of the borehole as the liquod fraction passes into the formation

Answer 8

Mudcake

Question 9

Steel pipe, square or hexagonal in cross section and approximately 12 m long. It is attached to the drill string and fits into the rotary table, transmitting the rotary motion of the table to the drill string

Answer 9

Kelly

Question 10

Rotating journal box (shaft and bearing) in the center of the rotary table through which the kelly passes.

Answer 10

Kelly bushing

Question 11

That part of the rock formation adjacent to a borehole that is penetrated by a mud filtrate

Answer 11

Invaded zone

Question 12

Log that measures the secondary magnetic field induced in the rock formation by alternating currents transmitted from the electric coils in the logging tool.

Answer 12

Induction log

Question 13

Log of natural gamma radiation from rocks, sources are dominantly minerals containing Thorium, Potassium and Uranium

Answer 13

Gamma Ray Log

Question 14

That part of the rock formation immediately adjacent to the borehole in which the original pore space fluid is replaced by the liquid infiltrate of the drilling mud.

Answer 14

Flushed zone

Question 15

in rotary drilling, it is the assemblage of drill bit and drill pipe rotated in the borehole by the drilling rig at the surface

Answer 15

Drill string/Drill stem

Question 16

Mud circulated in the borehole during rotary drilling to bring drill cuttings to the surface.

Answer 16

Drilling mud

Question 17

Sample of drill cutting staken from the drilling mud as it circulates to the surface

Answer 17

Ditch sample

Question 18

well log of formation density as determined by the backscatter of gamma rays from a source such as cobalt-60 or cesium-137 contained in a sonde passed up the borehole

Answer 18

Density Log