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My Geol > Drilling Methods > Flashcards

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
Q

Conventional rotary drilling methods:

A
  1. Mud rotary

2. Air rotary

26
Q

Explain mud rotary

A

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
Q

Explain air rotary

A
  • 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
Q

Reverse rotary drilling method

A

Same as general process for conventional mud rotary, but mud circulation direction is revered

Large borehole (d~60 to 180cm)

29
Q

Explain Becker hammer

A

A special type of reverse rotary

  • can deal with gravels (lots of gravel in Alberta)
  • depth ~60m
30
Q

Explain down the hole air hammer wells

A

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
Q

plump versus straight wells

A

Straight -> perfect alignment of casing sections

Plumb-> borehole will track an imaginary (straight) line from surface to centre of earth

32
Q

True or false: a well can be straight and not plumb

A

True

33
Q

True or false: a well can be plumb and not straight

A

False

34
Q

What are the minimum safety requirements on drilling site

A
  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

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