Pore Pressure Prediction

[aows51]

for the first question, i think it is because of the centroid effect

[petrogeo_69]

Q1 - in most cases these are younger sediments, where time, overburden pressure and temperature have not allowed for over-pressure to develop. Also, there is rarely the sealing or confining capacity of over laying sediments to trap building fluid pressure.
Q2- a general rule is that with increased depth = increased compaction = increased pressure and increased temperature.
Q3- many factors effect over pressure build-up 1st & foremost is rate of deposition & compaction.
Q4- LOT is a test of Rock Strength, rock strength governs confining pressure. so, if a LOT is tested to 15.0 ppg (which means it took the equivalent of 15.0 pounds per gallon pressure in a wellbore's annulus to progagate fluid into the rock or to break it down) this test is done at the shallowest open hole point in order to determine a safe drilling margin between over-pressure (pore pressure) and rock strength (fracture gradient).