Eval-Module 4 Flashcards
What do GR/CCL logs do?
Correlate open-hole logs to markers in/behind the casing
What do CBL/VDL log asses?
Hole intergrity (casing-cement-formation)
TDT logs/Sonic logs/Neutron-density logs/resistivity logs monitor/improve production by?
- evaluating the formation for Sw
- determining down=hole flow rates and the type of production
What are the 2 major areas of cased hole logging?
Production logging
Reservoir monitoring
Define production logging
to obtain production injection profiles over a completed interval
Define Reservoir monitoring
To obtain real time information about changes in hydrocarbon saturation
what does CCL stand for?
Casing Collar Location Tool
What does CBL stand for?
Cement bond log
What is the most effective correlation log and what does it measure and how?
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.
What are some challenges of GR in cased holes?
- Fragile
- must be run slowly
What do CCL tool’s correlate?
Open-hole logs to markers in the casing
What dies the CCL tool consist of?
permanent magnet
electrical coils
What does the CCL tool run in conjunction with?
runs with GR log (known as GR/CCL tool) to easily and quickly relate open-hole logs to this detectable casing feature.
What does the CCL tool reveal?
The exact depths f the zones to be perforated.
What are 4 problems related to a poor cement job?
- affect hydraulic isolation of zones
- reduce productivity through mingling fluids
- Expose pipe to corrosion
- allow saline water to contaminate fresh water
What does the CBL asses?
The quality of bonding between casing/cement/borehole
How do CBL work?
- Applies sonic waves and records their transit time using 1 transmitter and 2 receivers
- Emits pulses of sound energy that travel in all directions
What do the upper and lower receiver record in a CBL?
UPPER- records acoustic energy returned from cement-casing contact (CBL)
LOWER- records cement bond to formation (VDL)
What does VDL stand for?
Variable density log
What are some formation related problems shale can cause?
Geo pressure shale Reactive shale (swelling)
What are the top 6 sources of downhole problems and which are geology related?
Equipment failure Cement problems Stuck pipe lost circulation wellbore stability well control (last 4 geology related)
What are the 5 typical logs on a CBL presentation?
Transit time Gamma Ray CCL Amplitude VDL
What does CBL measure?
the amplitude (mV) transit time (delta t)
Define attenuation of the signals
as sound travels fastest through the steel casing, the receiver signals are affected by the % of casing bonded to the cement (aka-BI)
