The Theory Analyses And Application Of The Positive Displacement Mortor In Well Straightening

How to increase the rate of penetration during controlling deviation of vertical well is the most important thing for all the drilling engineers. The structure of drill-assembly (positive displacement mortor+PDC) can work on relatively high rotating velocity under low WOB, at the same time, it can control the deviation. It is benefit to control hole deviation compare with the traditional pendulum drill-assembly, so it has been used widely at all over the world.This paper analyzed the mechanism of well straightening and improving the rate of penetration, show three type of the structure of drill-assembly, We established mechanics modal based on differential equation and get the answer, which present a method to quantitatively analyze screw drill controlling the deviation.This paper analyzed the mechanism at the point of the mechanics with the example of drill-assembly which was used in Egypt BEA W-1X and in Dabei oil field. We get the answer that the different effect with different drilling parameter. So the position of stabilize、size of stabilizer、WOB、deviation、the angle of the motor will make the direct effect about the bit side force. So we can change the parameter for well straightening according to the analyzed.