We still have the same question as the previous post, Pressure Loss and Equivalent Circulating Density Review, but this case we will do reverser circulation, circulating from annulus to tubing , and see how much pressure and equivalent circulating density at bottom hole.
This example that I got from my junior member is very simple but it helps you a lot to understand about how to determine pressure loss during normal circulation.
Information given is listed below;
Circulate at 3 bottom up through open end tubing (Down tubing and up annulus) with 12.7 ppg mud.
Pump pressure = 1000 psi
Annulus friction loss = 50 psi
Inside tubing friction loss = 925 psi
Surface line friction loss = 25 psi
I still have the simple but interesting question about hydrostatic pressure which you can apply this calculation into drilling/cementing operation. The question I got about how much pressure we will see at cement head in case of float shoe fail.
In some cementing operation, operators will pump 2 cement slurries, normally called “Lead Cement” and “Tail Cement”. Both lead and tail cement have pro and con as described below.
Lead cement: Lead cement is in the top section of cement, where has lower both pressure and temperature (see figure above). It has lower density and strength than Tail cement; however, it is also cheaper than Tail cement.
Tail cement: Tail is pumped after lead cement because it must be settled at the lower section of well bore, where needs high strength cement (see figure above) . It has higher strength than lead cement, but it is more expensive than lead cement.
Ref books: 
Cementing Technology Books
Cement Bond Log: It measures integrity of cement bond between tubing/casing and well bore. The log is typically obtained from one of a variety of sonic-type tools. The newer versions, called “cement mapping”, can give detailed, 360-degree representations of the integrity of the cement job, whereas older versions may display a single line representing the integrated integrity around the casing (see Figure below).
Concept of CBL: Transmitter sends acoustic wave to casing/cement and then receivers receive acoustic signal that transfer through casing to cement and reflects to receivers. Acoustic wave at receivers is converted to amplitude (mv). Low amplitude represents good cement bond between casing and hole; however, high amplitude represents bad cement bond. The concept likes when we knock pipe. If there is something coverage around pipe, the reflection sound will be attenuated, and vice versa (see Figure below).
Tool component for CBL currently mostly consists of following equipment:
Gamma Ray/ CCL: It is used as correlation log. Gamma ray measures formation radiation and CCL records collar depth in tubing. Correlation log is a reference for a number of cased hole jobs as perforation, set plug, set patch, etc.
CBL/VDL: CBL measures cement bond integrity between casing/tubing and well bore. It apply concept of acoustic wave transferring through media. VDL is the top view of the cut away of upper part of acoustic wave that represents how cement bond from casing to wellbore
Caliper: Caliper measures wellbore diameter.
Example of CBL is shown below.
Downhole conditions that can cause errors in acoustic CBL interpretation or reliability are as follows:
Cement sheath thickness: Cement-sheath thickness may vary, causing changes in attenuation rate. The suitable cement thickness of 3/4 in. (2 cm) or more is required to achieve full attenuation.
Microannulus: A microannulus is a very small gap between casing and cement. This gap would affect the CBL presentation. Running the CBL under pressure can help eliminate the microannulus.
Centralize tool: Tool must be centralized in order to get the accurate amplitude and time.
Ref books: Cementing Technology Books
