Chapter 11
** Proper cement placement between the well casing and the formation is essential:
 To support the casing.
 To prevent fluid from leaking to the surface.
 For isolating producing zones from water-bearing zones.
** Acoustic logs provide the means for evaluating the integrity and quality of the cement.
** Cement Bond Log (CBL):
 Acoustic logs do not measure cement quality directly.
 Value is inferred from the acoustic (sound) wave of the cement to the casing.
 The CBL gives a continuous measurement of the amplitude (strength) of sound from a
source to sensor.
 Modern acoustic cement (bond) devices are one or more source and two or more sensor.
 They operate on the principle that amplitude is rapidly attenuated in good cement bond
and not in partial bond (bad cement) or free pipe.
 These tools measure are:
1. Compressional2. Amplitude (mV)
3. Attenuation per unit distance.
** Weak sound  Good cement ///////// Strong sound  bad cement
** Amplitude, measured directly is the primary measurement that provides:
 Quality of cement job.
 Can handle pressure.
 Bond index.
** Full acoustic wave can be displayed as a Variable Density Log (VDL) where positive and
negative of the wave are shaded black and white.
** Variable density display of full-waveform amplitude as shades of black and white.
** On a variable-density log, free pipe (bad cement) easily identified as straight dark and light
lines.
** The zigzag, wavy pattern is the formation signal. (formation mean cement)
Chapter 12
** Formation Testing is to confirm and have more idea about rocks and types of fluid by
taken samples after drilling.
** Formation testing tools include:
 Formation Tester (FT)
 Formation Interval Tester (FIT)
 Repeat Formation Tester (RFT)
** Formation Tester (FT) operation:
 Tool is positioned in depth using SP and GR log.
 The pad is pushed strongly against borehole.
 Expansion between the pads is achieved using hydraulic pressure.
 Flow valve is opened and fluids flow into sample chamber.
** Formation Interval Tester (FIT) operation:
 Chosen depth by SP and GR log.
 Flow valve is opened to allow formation fluid to enter sample chamber.
 Firing of shaped charge
 Sample chamber is full and closed once static reservoir pressure is reached.
 Hydraulic pressure is released, and pads closed.
** Why Repeat Formation Tester (RFT) design?
The other tools allow only one sample to be collected and one pressure test to be made so tools
need to be brought out of hole before next test and this leads to loss of rig time so repeat
formation tester tool was designed.
** Repeat Formation Tester (RFT) Characteristics:
 In one trip in hole, tool can be set any number of times for pressure measurement.
 It is possible to pretest a formation to choose most permeable zones on which fluid
samples should be taken. If pretest is convincing, sample chamber is opened.
 There are 2 sample chambers, it is possible to do sampling twice.
 More accurate tools with less errors.
Note Chapter 13,14,15,16 need to understand