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Flashcards in Drilling methods Deck (23):
1

Drilling is used in

a) site assessments -- collection of samples
b) installing water monitoring wells
c) installing producing water wells

2

How to choose a drilling method

a) purpose of drilling program
b) geology
c) drilling depth
d) site accessibility
e) cost/availability of eqpt.

3

Make footage

Drilling as fast as you can

4

Cavings

Pieces of sides of the boreholes which have collapsed into the hole

5

Lost circulation

Drilling fluids seep into poros or high K units, drilling fluids leave the borehole

6

Mud cake (filter cake)

Build up of solids from the mud onto the borehole walls across from permeable zones

7

Cuttings (chips)

V. small pieces of rock that have been ground up by the drill bit

8

Lag time

time b/t when the chips are cut and when they come to surface

9

Tripping in/out

The time it takes to put the bit in or out of the borehole

10

Fishing

Drillers of loggers have lost a tool downhole

11

Driven wells

Dry point or sand point

installed by using a sledge hammer

Shallow, small borehole, unconsolidated

12

Direct push wells

Hydraulic units, mounted on trucks, push a steel barrel in the ground

Shallow, unconsolidated

13

3 types of auger wells: Rotary bucket

NO FLUIDS

90cm cylindrical bucket, unconsolidated material

14

3 types of auger wells: Hollow stem auger

NO FLUIDS

hollow stem pipe encircled by flights, driven by a rig w/ a rotary head

monitoring wells can be placed down the hollow stem before removing the auger

15

3 types of auger wells: solid stem auger

NO FLUIDS

Solid stem pipe encircle by flights, driven by a rig w/ a rotary head

16

Cable tool wells

Earliest developed, drilling stopped periodically to remove cuttings, 40-60 cm diameter

17

2 types of drilled wells: Conventional rotary

USE FLUIDS

Rotation of a bit on the end of a drill pipe at high speeds
drilling fluids carry cuttings through the annulus

mud and air rotary fluids

18

2 types of drilled wells: Reverse rotary

Same drilling process as for conventional mud rotary but the mud circulation is reversed

borehole is 60-180cm

19

Types of drilling bits

Bits chosen based on geology

a) drag bits -- for unconsolidated sediments
b) roller cones -- for rocks
c) diamond core drill bits

20

Down the hole air hammer wells

Pneumatic drill at the end of the drill pipe hits the rock as the drill pipe is rotated, air is used to remove cuttings

21

Straight well

perfect alignment of the casing sections

22

Plumb well

The borehole will track an imaginary line from the surface to the center of the earth

23

Drilling safety

-steel toed boots
-safety goggles
-vest
-hard hat
-gloves