Pressure Testing Detective
On a valid pretest, what part of the pressure-time curve is used to estimate formation pressure?
The stabilization portion of the pressure build up
Which test type indicates the probe never achieved hydraulic communication with the formation?
Dry Test
What is the primary purpose of MDT fluid sampling?
Obtain representative formation fluid samples.
What is the primary purpose of cement behind casing?
Zonal Isolation
A pressure point was planned in a clean sandstone, but the probe landed on a shale streak. What is the most likely result?
A dry test or poor quality test
Two valid tests have identical drawdown pressures, but one recovers much faster. Which formation has higher mobility?
The one with the faster recovery.
Which test generally exhibits the largest drawdown and slowest recovery?
Tight test
Which MDT component provides real-time optical fluid characterization downhole?
LFA (Live Fluid Analyzer)
Which traditional cement evaluation tool combines amplitude and waveform analysis?
CBL/VDL
Why does a poor probe seal often result in formation pressure not being measured correctly?
Mud filtrate leaks around the probe, preventing proper hydraulic isolation.
What phenomenon causes measured pressure to be higher than true formation pressure near the borehole?
Supercharging
What operational issue is most commonly responsible for a lost seal test?
Poor pad/probe sealing against the formation.
What do we look at to differentiate between OBM and Formation Oil
GOR
Which ultrasonic tool generates a full circumferential image of cement quality?
USIT
A formation has excellent porosity but extremely low permeability. What pressure-testing challenge is most likely?
Very slow pressure buildup (tight test behavior).
A pressure curve shows significant drawdown but almost no buildup recovery. What type of test is this?
Tight Test
Why can a highly permeable formation sometimes show very little drawdown?
High mobility
Why is pressure testing usually performed before sampling?
To verify reservoir communication and identify the best sampling locations.
What cement defect is present when fluid can move vertically through a localized pathway behind casing?
Channeling
Name two drilling-related factors that can increase supercharging.
Overbalance pressure and low formation mobility.
During a pretest, pressure suddenly drops toward mud pressure instead of stabilizing. What is the most likely interpretation?
Lost seal test
A test appears valid, but the measured pressure is consistently above neighboring pressure points. What phenomenon should be suspected?
Supercharging
An LFA response suddenly changes from oil characteristics to gas characteristics while moving up the reservoir. What could have happened
Gas-Oil-Contact (GOC)/ Bubble point
A CBL-VDL log shows low CBL amplitude, no casing arrivals, and strong formation arrivals. What cement condition does this indicate, and why?
This indicates good cement bonding to both casing and formation
During station selection, why might an image log be more useful than a triple-combo log for avoiding test failures?
It can reveal fractures, vugs, breakouts, and small-scale heterogeneities that are not visible on conventional logs.