Chaper 8 High Pressure High Temperature Wells

Question 1

Define the temperature and pressure characteristics of an HPHT well?

Answer 1

Formation temperature greater than 177C or pressure control equipment with a rated working pressure in excess of 103.5MPa

Question 2

Explain the mechanism by which supercharging occurs?

Answer 2

Circulating pressure force mud into fractures in the rock which increase in length as the pressure continues to be applied. When pressure is released or reduced then the fractures close up, forcing fluid back into the wellbore and causing an apparent ‘flow’ at surface.

Question 3

Which well control method should be used to circulate the well if flowback occurs?

Answer 3

The Drillers Method is proffered.

Question 4

Explain the difference between flowback and drainback

Answer 4

Flowback - An influx of mud at surface that occurs from released pressure in the formation fracture when the pumps are turned off

Drainback - The rise in pit level seen when circulation stops and mud in the tanks, lines and shaker trays downstream of the flow line.