Abstract: A method of warning of the onset of pipe sticking in a rotary drilling operation using a drill string comprising: (a) monitoring the pressure of a drilling fluid being pumped through the drill string during drilling over predetermined periods of time to obtain series of pressure measurements; (b) monitoring the torque required to rotate the drill string during said periods to obtain series of torque measurements; (c) obtaining the skew (third moment) of each series of pressure measurements according to the relationship ##EQU1## wherein N is the number of pressure measurements xi in the series, xmean is the average value of the measurements in the series, and .sigma. is the standard deviation of the measurements in the series; (d) obtaining the normalized standard deviation .sigma.n of the torque measurements in each corresponding series of torque measurements according to the relationship .sigma.n=(.sigma./ymean) wherein .sigma.

Abstract: To optimize the drilling of a borehole with a positive displacement downhole mud motor which rotates a drill bit, the hydraulic power input to the motor and the mechanical power output of the motor are calculated based upon measurements of weight-on-bit (WOB), torque, bit rotational speed and pressure drop across the motor. These input and output values are plotted versus one another to produce a characteristic curve which indicates the maximum achievable power output of the motor. The values used by the driller are compared to such maximum to enable adjustment of WOB such that drilling at maximum efficiency for a given lithology can be achieved. Other important information such as optimum standpipe pressure and operating efficiency and wear of the motor also are determined.

Abstract: A method of determining fluid influx or loss from a well being drilled from a floating vessel and using a drilling fluid, the method comprising monitoring the flow of fluid from the well to obtain a varying signal indicative of the variation in flow from the well, monitoring the heave motion of the vessel to obtain a varying signal indicative of said motion, using the signal indicative of the heave motion to calculate the expected variation in fluid flow from the well due to said motion, using said calculated flow to correct the varying flow signal to compensate for any flow component due to heave motion and monitoring the compensated signal for an indication of fluid influx or loss from the well.

Abstract: A method of detecting a fluid influx in a well being drilled with a drill string having a drilling fluid circulated therethrough from a tank via a supply line system connected to the drill string, the method being used while connecting or disconnecting a pipe to or from the drill string and comprising the steps of:a) ceasing circulation of the drilling fluid;b) disconnecting the supply line system from the drill string so as to allow any drilling fluid in the system to flow back into the tank while connecting or disconnecting a pipe;c) reconnecting the supply line to the drill string and recommencing circulation of the fluid;d) while repeating a)-c) during the normal course of drilling the well, monitoring the change in level of fluid in the tank so as to determine a model of the change in level in the tank with respect to time during steps a)-c); ande) comparing the change in tank level observed when subsequently performing steps a)-c) with the change predicted by the model so as to detect a difference there

Abstract: A method for the estimation of pore pressure within a subterranean formation containing fluid during the drilling of a bore hole. The bore hole is drilled using a drill string consisting of a drill bit fitted to its lower end, and using drilling mud pumped from the surface through the drill string and finally evacuated.