Published February 2015

Defining of drilling mud adsorption depth in the well

V.N. Samadov

Y.I. Safarov

M.M. Shirinov

E.T.Ismailov

The adsoprtion of drilling mud depends on formation characteristics, drilling mud parameters and overpressure on stratum. The drilling experience shows that hydrostatical pressure is generally for 3.0-5.0 MPa higher than formation pressure. During descent of drilling tool into the well or recovery of washing fluid circulation in bottomhole zone, the overpressure on the formation appears. The methodics on defining of drilling mud adsorption site or its lost while descending of drilling tool and casing is offered. Using the equation of pressure balance in circulation system, a formula is obtained and an algorithm for defining of drilling mud adsorption or lost developed.