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Log Analysis- Eval 305- Log Analysis Fundamentals > Eval-Module 4 > Flashcards

Eval-Module 4 Flashcards

1
Q

What do GR/CCL logs do?

A

Correlate open-hole logs to markers in/behind the casing

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2
Q

What do CBL/VDL log asses?

A

Hole intergrity (casing-cement-formation)

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3
Q

TDT logs/Sonic logs/Neutron-density logs/resistivity logs monitor/improve production by?

A
  • evaluating the formation for Sw

- determining down=hole flow rates and the type of production

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4
Q

What are the 2 major areas of cased hole logging?

A

Production logging

Reservoir monitoring

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5
Q

Define production logging

A

to obtain production injection profiles over a completed interval

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6
Q

Define Reservoir monitoring

A

To obtain real time information about changes in hydrocarbon saturation

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7
Q

what does CCL stand for?

A

Casing Collar Location Tool

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8
Q

What does CBL stand for?

A

Cement bond log

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9
Q

What is the most effective correlation log and what does it measure and how?

A

Gamma Ray

  • the radiation is measurable through casing
  • depth measurements are precise and easy to compare with open-hole gamma ray logs as perforation must run exactly where they should be.
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10
Q

What are some challenges of GR in cased holes?

A
  • Fragile

- must be run slowly

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11
Q

What do CCL tool’s correlate?

A

Open-hole logs to markers in the casing

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12
Q

What dies the CCL tool consist of?

A

permanent magnet

electrical coils

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13
Q

What does the CCL tool run in conjunction with?

A

runs with GR log (known as GR/CCL tool) to easily and quickly relate open-hole logs to this detectable casing feature.

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14
Q

What does the CCL tool reveal?

A

The exact depths f the zones to be perforated.

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15
Q

What are 4 problems related to a poor cement job?

A
  • affect hydraulic isolation of zones
  • reduce productivity through mingling fluids
  • Expose pipe to corrosion
  • allow saline water to contaminate fresh water
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16
Q

What does the CBL asses?

A

The quality of bonding between casing/cement/borehole

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17
Q

How do CBL work?

A
  • Applies sonic waves and records their transit time using 1 transmitter and 2 receivers
  • Emits pulses of sound energy that travel in all directions
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18
Q

What do the upper and lower receiver record in a CBL?

A

UPPER- records acoustic energy returned from cement-casing contact (CBL)
LOWER- records cement bond to formation (VDL)

19
Q

What does VDL stand for?

A

Variable density log

20
Q

What are some formation related problems shale can cause?

A 
Geo pressure shale
Reactive shale (swelling)
21
Q

What are the top 6 sources of downhole problems and which are geology related?

A 
Equipment failure
Cement problems
Stuck pipe
lost circulation
wellbore stability
well control
(last 4 geology related)
22
Q

What are the 5 typical logs on a CBL presentation?

A 
Transit time
Gamma Ray
CCL
Amplitude
VDL
23
Q

What does CBL measure?

A 
the amplitude (mV)
transit time (delta t)
24
Q

Define attenuation of the signals

A

as sound travels fastest through the steel casing, the receiver signals are affected by the % of casing bonded to the cement (aka-BI)

25
Q

Whats considered a good BI and bad BI?

A

good >.80

bad<.80

26
Q

are CBL good in oils and water zones or good in gas zones?

A

good-oil/water zones

poor- gas zones

27
Q

Which way to signals peak in CBL’s and what do they mean?

A

Highest amplitude- signals peak to the right (max attenuation)= FREE PIPE

Lower amplitude- signals peak to the left (min attenuation)=
BETTER BOND BETWEEN CASING AND CEMENT

28
Q

What do VDL’s measure?

A

The bond between formation and the cement

29
Q

What 3 recordings do VDL logs consist of?

A
  • Arrival time from casing
  • Arrival time from formation and cement
  • Arrival time from mud
30
Q

What 4 logs are used to monitor/improve production by evaluating sw of the formations?

A

TDT logs
Sonic Logs
Neutron-Density logs
Resistivity logs

31
Q

What 4 logs are used to monitor/improve production by determining down hole flow rates/production?

A

Flowmeter logs
Radioactive tracer logs
temperature logs
noise logs

32
Q

What is a TDT log?

What odes it capture?

A

Thermal Decay Time Log

is a pulsed neutron tool to determine sw behind casing

It captures sigma, cross section

33
Q

When does channeling occur?

A

when a vertical portion of the pipe is NOT bonded over a significant distance

34
Q

When does a microannulus occur?

A

when small gaps are formed between casing and cement in an otherwise well-cemented casing

35
Q

What 3 things does sigma in a reservoir rock depend on?

A
  1. porosity
  2. salinity
  3. qty & type of HC
36
Q

What 5 things do you need to know in a TDT log?

A
  1. porosity
  2. water salinity
  3. lithology
  4. shaliness
  5. type of HC
37
Q

What casing logs are used primarily to determine Sw?

A
  1. Sonic
  2. CNL (neutron porosity)
  3. density
  4. Resistivity
38
Q

How does a radioactive tracer log work?

A

a radioactive fluid is injected along with injection water to determine if the perforation are isolated or if leakage has occurred.

39
Q

What is noise logging primarily used for?

A

Channel detection

Measure flow rate

40
Q

What is a noise log?

What does high and low amplitude indicate?

A

a records of the sound measured at different position in the borehole

HIGH- greater turbulence such as leaks, channels
LOW- low turbulence, no channeling

41
Q

What are different frequency ranged tied to in noise logs?

A

to different sources of noise or different flow regimes

42
Q

What does a temperature log determine?

A

fluid entries-especially gas

eg. when gas flows through perforation, pressure decreases and temperature decreases.

43
Q

What is one way to determine flow behind casing with a temperature log?

A

shut in well for several days so temperature can stabilize.

Log Analysis- Eval 305- Log Analysis Fundamentals (9 decks)

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