Method for Control of a Drilling Operation

Abstract

A method for controlling a drilling operation, in particular in production or exploration drilling for hydrocarbons, in which a drill bit is arranged on an end of a drill string and, by rotation and pressure against an underground formation, is arranged to form a borehole, and in which a drilling fluid is circulated through a pipe bore into the borehole at the drill bit to convey cuttings out of the borehole. The method comprises the steps of: providing data on the particle size distribution of the cuttings; comparing the provided particle size distribution with data for the desired particle size distribution when drilling in the underground formation of interest; and adjusting the critical control parameters of the drilling operation with the aim of achieving a cuttings particle size distribution which corresponds, to the greatest extent possible, to the desired particle size distribution.

1 . A method for controlling a drilling operation, in production or exploration drilling for hydrocarbons, in which a drill bit is arranged on an end of a drill string and, by rotation and pressure against an underground formation, is arranged to form a borehole, and in which a drilling fluid is circulated through a pipe bore into the borehole at the drill bit to convey cuttings out of the borehole, the method comprising the steps of:
 providing data ( 17 ,  27 ,  37 ,  47 ) on the particle size distribution of the cuttings;   comparing the provided particle size distribution with data for a targeted particle size distribution when drilling in the underground formation of interest; and   adjusting the critical control parameters of the drilling operation with the aim of achieving a cuttings particle size distribution which corresponds, to the greatest extent possible, to the targeted particle size distribution;   the critical control parameters of the drilling operation including the work pressure of the drill bit against the underground formation, the rotational speed of the drill bit, the composition of the drilling fluid, and the flow rate of the drilling fluid in the borehole.   
     
     
         2 . The method in accordance with  claim 1 , wherein the cuttings particle size distribution is provided by at least a representative portion of the cuttings-laden drilling fluid being carried to a separating system ( 1 ) arranged to fraction the cuttings particles. 
     
     
         3 . The method in accordance with  claim 2 , further including a separating system ( 1 ) having a plurality of shale shakers ( 11 ,  21 ,  31 ,  41 ) connected in series, each shale shaker ( 11 ,  21 ,  31 ,  41 ) being arranged to separate a fraction (A, B, C, D) of particles over a specific screening size and keep each fraction (A, B, C, D) separated from the fractions (A, B, C, D) separated from other shale shakers ( 11 ,  21 ,  31 ,  41 ) in the separating system ( 1 ). 
     
     
         4 . The method in accordance with  claim 2 , wherein each fraction (A, B, C, D) is quantified in the form of weight or volume. 
     
     
         5 . The method in accordance with  claim 3 , wherein each of the separate particle fractions (A, B, C, D) is distributed to further processing.