Hossein Yavari - M.Sc Student at Amirkabir Universityof Technology, Drilling Engineering
Mohammad Fazaelizadeh - Faculty Member of Amirkabir University of Technology
Rasool Khosravanian - Faculty Member of Amirkabir University of Technology
Vahab Hassani - Head of Bit Operation & Drilling Optimization, Dana Energy

Drill-off test is used to determine the optimum WOB and RPM during drilling. In this test the WOB that gives the highest ROP is considered as the optimal value. In 1991, Bourgoyne et.al introduced the maximum rate of penetration point as a non-optimal point because at this point available hydraulic cant clean underneath the bit and the bit crushes cuttings from previous step for another time, causing over wearing of the bit, bit balling and vibrations. The point that has the minimum MSE and maximum mechanical efficiency is the optimal point. This point is called founder point.

Mechanical Specific Energy, Rate of Penetration, Artificial Neural Network, Mechanical Efficiency, Weight on Bit, CCS