Apparatus and method for early kick detection and loss of drilling mud in oilwell drilling operations

Abstract

The flow of well mud being pumped by a drilling rig pump into a wellbore is sensed by monitoring at least one signal from at least one sensor of drilling mud, determining a total well drilling pump mud output rate, and determining an apparent annular mud rate based on the at least one signal and the total pump drilling rate.

1 . A well mud monitoring method, the well mud being pumped by a drilling rig pump into a wellbore, the wellbore including a return wellbore having a central axis for returning well mud to the drilling rig pump, the method comprising:
 a) monitoring at least one signal from at least one sensor of drilling mud,   b) determining a total well drilling pump mud output rate,   c) determining an apparent annular mud rate based on the at least one signal and the total pump drilling rate.   
     
     
         2 . The well mud monitoring method of  claim 1 , further comprising monitoring a flow rate of at least one additional fluid being added to the well drilling mud output, and reducing the apparent annular mud rate by the flow rate of the at least one additional fluid. 
     
     
         3 . The well mud monitoring method of  claim 1 , further comprising monitoring the amount of drilled cuttings and wellbore cavings in the drilling fluid, and adjusting the apparent annular mud rate based on the amount of drilled cuttings and wellbore cavings in the drilling fluid. 
     
     
         4 . The well mud monitoring method of  claim 1 , further comprising determining the apparent annular mud rate at at least two times, and comparing the apparent annular mud rate at the at least two times to determine whether the wellbore is gaining or losing drilling mud. 
     
     
         5 . The well mud monitoring method of  claim 4 , further comprising providing a drill string and lowering the drill string into the wellbore at a downward drill string displacement rate, and comparing the apparent annular mud rate with the downward drill string displacement rate to determine whether the wellbore is gaining formation fluid or drilling mud is being lost to the wellbore. 
     
     
         6 . The well mud monitoring method of  claim 4 , further comprising providing a drill string and raising the drill string out of the wellbore at an upward drill string displacement rate, and comparing the apparent annular mud rate with the upward drill string displacement rate to determine whether the wellbore is gaining or losing drilling mud while raising the drill string out of the wellbore. 
     
     
         7 . The well mud monitoring method of  claim 1  further comprising providing a motionless drill string to detect a wellbore return flow. 
     
     
         8 . The well mud monitoring method of  claim 1  further comprising providing the at least one sensor in a flow chamber. 
     
     
         9 . The well mud monitoring method of  claim 8  further comprising providing a first set of at least two sensors, the first set of at least two sensors being positioned on an axis parallel the central axis of the return wellbore. 
     
     
         10 . The well mud monitoring method of  claim 9  further comprising providing a second and third set of at least two sensors, the axes of the second and third sets of at least two sensors being parallel to the central axis of the return wellbore, the axes of the sets of at least two sensors being spaced 120 degrees from one another as determined on a plane perpendicular to the central axis of the return wellbore. 
     
     
         11 . The well mud monitoring method of  claim 8 , further comprising providing a central pipe and at least one flow tube in the flow chamber, the flow tube being in fluid communication with the central pipe, the central pipe having an inlet to the flow tube and an outlet from the flow tube, the at least one sensor being positioned in the at least one flow tube. 
     
     
         12 . The well mud monitoring method of  claim 11 , further comprising providing a first set of at least two sensors in the at least one flow tube 
     
     
         13 . The well mud monitoring method of  claim 12  further comprising providing the first set of at least two sensors on an axis parallel to the axis of the return wellbore. 
     
     
         14 . The well mud monitoring method of  claim 11  further comprising providing a second and third set of at least two sensors, the axes of the second and third sets of at least two sensors being parallel the central axis of the return wellbore, the axes of the sets of at least two sensors being spaced 120 degrees from one another as determined on a plane perpendicular to the central axis of the return wellbore. 
     
     
         15 . The well mud monitoring method of  claim 1 , wherein the at least one sensor includes at least one pressure sensor. 
     
     
         16 . The well mud monitoring method of  claim 1 , wherein the at least one sensor includes at least one flow sensor. 
     
     
         17 . The well mud monitoring method of  claim 1 , further comprising determining at least one of:
 (i) whether drilling mud is being lost or gained;   (ii) the rate at which drilling mud is being lost or gained;   (iii) the increase or decrease in the wellbore flow rate relative to the drilling pump output;   (iv) the cumulative volume of drilling mud lost or gained;   (v) the level of the drilling mud in the wellbore; and   (vi) alarms for the drilling operation per an operator's requested parameters.   
     
     
         18 . A method for early detection of drilling mud gains or losses in oil well drilling operations comprising
 a) monitoring the output of at least one pair of an upper and lower pressure sensors positioned in a return wellbore of a petroleum well,   b) comparing the output of the upper pressure sensor with the output of the lower pressure sensor to establish whether the return wellbore is gaining or losing fluid, and   c) comparing the gain or loss of fluid with a first predetermined parameter.   
     
     
         19 . The method of  claim 18  further comprising:
 a) monitoring the output of at least one flow sensing device to establish whether the return wellbore is gaining or losing fluid, 
 b) comparing the output of the at least one flow sensing device to the difference between the output of the upper and the lower pressure sensing outputs to confirm whether the return wellbore is gaining or losing fluid. 
 
     
     
         20 . A method for early detection of drilling mud gains or losses in oil well drilling operations comprising:
 a) monitoring the output of at least one flow sensing device to establish whether the return wellbore is gaining or losing fluid, and   b) comparing the gain or loss of fluid with a first predetermined parameter.