Drilling Methods Flashcards

1
Q

Drilling is used in

A
  • site assessments for the collection of soil and water samples
  • installation of water monitoring wells
  • installation of producing wells
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2
Q

Drilling method depends on:

A
  • purpose of drilling program
  • geology
  • drilling depth
  • site accessibility
  • available equipment
  • cost
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3
Q

What does make footage mean?

A

Drilling as fast as they can

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4
Q

What does cavings mean?

A

Pieces of sides of borehole will collapse into hole

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5
Q

What does lost circulation mean?

A

Drilling fluids (muds) leave the borehole and enter (lost in) a subsurface formation

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6
Q

What does mud cake mean?

A

(Filter cake) build up of solids from the mud into the borehole wells from the mud across from K zones

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7
Q

What does cuttings mean?

A

(Chips) very small pieces of rocks that have been ground up by the drill bit to create the borehole

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8
Q

What does lag time mean?

A

Time between when the chips are cut down hole and when they arrive at surface

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9
Q

What does tripping in/out mean?

A
  • time it takes to pull the bit out of the hole (tripping out)
  • time it takes to put the bit in the hole (tripping in)
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10
Q

What does fishing mean?

A

Drillers or loggers have lost a tool (down hole and are trying to retrieve it)

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11
Q

Explain Driven wells

A

Installed by hand using a sledge hammer, percussion or a
Driver head

For shallow, small diameter drilling in unconsolidated seds

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12
Q

Explain Direct push wells

A

Hydraulic units, mounted in trucks, push a steel core barrel (d~6cm) into the ground

For shallow drilling in unconsolidated seds

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13
Q

Explain auger wells

A

Don’t need drilling fluid

3 types:

  1. rotary bucket
  2. Hollow stem auger
  3. Solid stem auger

Also hand augering

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14
Q

Explain a rotary bucket

A

Large diameter (d~90cm) cylindrical bucket with cutting blades at its base where it contacts soil

~80 x 90 cm casing sections can then be lowered into the angered hole

For unconsolidated material

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15
Q

Explain a Hollow stem auger

A

Hollow stem pipe encircled by ‘flights’

Auger is driven by a hydraulic rig with a rotary head

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16
Q

How can a hollow stem auger help with soil sampling

A
  1. Sample between borehole and auger

2. Sample through the augers hollow stem

17
Q

Explain solid stem auger

A

Solid stem pipe encircles by flights

Driven by hydraulic rig with a rotary head

Auger must be removed before you can put in a monitoring well

Sed must be cohesive

18
Q

Explain cable tool wells

A

Percussion drilling, shudder rigs

  • earliest form of drilling
  • involves lifting, dropping and rotating a heavy drill bit in end of cable

-you have to periodically stop and remove cuttings

Cuttings removed as a slurry

Large hole (d is 40-60cm)

19
Q

In cable tool wells what do you do if no water is naturally entering hole from surroundings

A

A little water is added to mix with the chips to bring them to surface as a slurry

20
Q

Explain drilled wells

A

-use drilling fluid

-2 types: 1. Conventional
Rotary and 2. Reverse rotary
Based in direction of mud flow in borehole

21
Q

Explain conventional rotary

A

Rotation of but on the end of a drill pipe at high speeds

  • drilling fluids pumped down through the drill pipe and out through holes in drill bit
  • fluids pick up cutting and bring them to surface through annulus

Subtypes based on fluid used (I.e. water, mud air,chemical foams)

22
Q

Purpose of drilling fluid in drilled wells is to:

A
  1. Lubricate bit
  2. Cool bit
  3. Bring chips to surface. A) don’t need to stop drilling(saves money). B) bit doesn’t get stuck in down hole (jamming)
  4. mud cakes over K brines. A) stop lost circulation. B) stops further contamination of formation
23
Q

Downsides to drilling muds

A
  1. Mudcake buildup -> seals off low yield aquifer
    (You may even miss it while drilling)
  2. P mud&raquo_space;> P formation
    - > will not push formation fluids from borehole
    - > won’t get representative sample
24
Q

Common drilling bits

A
  1. Drag bits
    - unconsolidated seds
  2. Roller cones (most common is tricone)
    - rocks
  3. Diamond core drill bits
    - hollow pipe with industrial diamonds (boarts) on it’s cutting edge
25
Conventional rotary drilling methods:
1. Mud rotary | 2. Air rotary
26
Explain mud rotary
Mud is used as drilling fluid and to bring cuttings to surface - borehole <60cm - drillers like this (fast) - good for high p deep Aguirre P mud > or equal to P formation (prevents formations fluids from going to surface too quick and causing a blowout
27
Explain air rotary
- used to bring cuttings to surface - compressed air is forced down through the drill pipe and out through bit and up to surface with chips - > no lost circulation - > rapid drilling - > aquifer not plugged by fluids
28
Reverse rotary drilling method
Same as general process for conventional mud rotary, but mud circulation direction is revered Large borehole (d~60 to 180cm)
29
Explain Becker hammer
A special type of reverse rotary - can deal with gravels (lots of gravel in Alberta) - depth ~60m
30
Explain down the hole air hammer wells
Pneumatic drill at the end of the -drill pipe hits therock(cable tool), -as drill pipe is rotated (rotary rigs) Combo of the two Air is used to remove cuttings Small well for bed rock (not good with unconsolidated seds
31
plump versus straight wells
Straight -> perfect alignment of casing sections Plumb-> borehole will track an imaginary (straight) line from surface to centre of earth
32
True or false: a well can be straight and not plumb
True
33
True or false: a well can be plumb and not straight
False
34
What are the minimum safety requirements on drilling site
1. steel toed boots 2. Safety glasses/gloves/vest 3. hard hat (no loose clothes) - line located, watch out for power lines, no drugs or alcohol