Anti-collision well trajectory design

Abstract

Techniques for determining trajectories for a plurality of wells while avoiding collision between wells are presented. The techniques can include determining a zone of uncertainty for individual wells of the plurality of wells, determining a minimum separation factor for individual wells of the plurality of wells, determining a gradient of a separation factor for at least one pair of wells of the plurality of pairs of wells, updating a nudge position for at least one well, and providing nudge positions for the individual wells of the plurality of wells.

1 . A method comprising:
 obtaining, by one or more processors, a respective nudge position for each of a plurality of wells;   determining, by the one or more processors, a zone of uncertainty for each of the plurality of wells, wherein each zone of uncertainty comprises a range of potential deviated locations for a location of a borehole of the respective well;   determining, by the one or more processors, based on the respective zone of uncertainty, a plurality of separation factors for each respective well;   determining, by the one or more processors, a minimum separation factor for each respective well from the respective plurality of separation factors;   comparing the respective minimum separation factor for each respective well to a threshold; and   storing or updating, by the one or more processors, in a memory, the respective nudge position for each respective well based on the comparison; and   outputting, by the one or more processors, a set of recommended nudging vectors, from the stored or updated nudge positions, to a display.   
     
     
         2 . The method of  claim 1 , wherein the storing or updating, by the one or more processors, in the memory, the respective nudge position for each respective well based on the comparison comprises storing the respective nudge position when the respective minimum separation factor for the respective well is at or above the threshold. 
     
     
         3 . The method of  claim 1 , wherein the storing or updating, by the one or more processors, in the memory, the respective nudge position for each respective well based on the comparison comprises updating the respective nudge position when the respective minimum separation factor for the respective well is below the threshold. 
     
     
         4 . The method of  claim 3 , wherein the updating the respective nudge position comprises:
 determining, by the one or more processors, a gradient of separation factor based on the respective plurality of separation factors and zones of uncertainty for a pair of wells of the plurality of wells; and   updating the respective nudge position, based on the gradient of separation factor and the respective plurality of separation factors.   
     
     
         5 . The method of  claim 1 , wherein the set of recommended nudging vectors comprises nudging vectors that cause the respective wells to avoid an obstacle. 
     
     
         6 . The method of  claim 1 , wherein the set of recommended nudging vectors comprises nudging vectors that cause the respective wells to intersect a target. 
     
     
         7 . The method of  claim 1 , wherein the plurality of wells comprise at least three wells. 
     
     
         8 . The method of  claim 1 , wherein the respective minimum separation factors are determined based on an oriented separation factor formula. 
     
     
         9 . The method of  claim 1 , wherein at least one respective zone of uncertainty lies in a plane and comprises at least one of an ellipse or a pedal curve. 
     
     
         10 . The method of  claim 1 , wherein the updating the respective nudge position comprises updating a position matrix with a move matrix comprising a plurality of nudge vectors. 
     
     
         11 . The method of  claim 1 , further comprising iterating until a stop condition occurs. 
     
     
         12 . The method of  claim 11 , wherein the stop condition comprises at least one of: a global minimum separation factor being above a predetermined threshold or a number of iterations exceeding a predetermined iteration ceiling, wherein the global minimum separation factor is a smallest separation factor of the respective minimum separation factors. 
     
     
         13 . A system comprising:
 memory;   one or more processors; and   a display,   wherein the one or more processors are configured to:
 obtain a respective nudge position for each of a plurality of wells; 
 determine a zone of uncertainty for each of the plurality of wells, wherein each zone of uncertainty comprises a range of potential deviated locations for a location of a borehole of the respective well; 
 determine, based on the respective zone of uncertainty, a plurality of separation factors for each respective well; 
 determine a minimum separation factor for each respective well from the respective plurality of separation factors; 
 compare the respective minimum separation factor for each respective well to a threshold; and 
 store or update, in the memory, the respective nudge position for each respective well based on the comparison; and 
 output a set of recommended nudging vectors, from the stored or updated nudge positions, to the display. 
   
     
     
         14 . The system of  claim 13 , wherein the storing or updating, by the one or more processors, in the memory, the respective nudge position for each respective well based on the comparison comprises storing the respective nudge position when the respective minimum separation factor for the respective well is at or above the threshold. 
     
     
         15 . The system of  claim 13 , wherein the storing or updating, by the one or more processors, in the memory, the respective nudge position for each respective well based on the comparison comprises updating the respective nudge position when the respective minimum separation factor for the respective well is below the threshold. 
     
     
         16 . The system of  claim 15 , wherein the updating the respective nudge position comprises:
 determining, by the one or more processors, a gradient of separation factor based on the respective plurality of separation factors and zones of uncertainty for a pair of wells of the plurality of wells; and   updating the respective nudge position, based on the gradient of separation factor and the respective plurality of separation factors.   
     
     
         17 . The system of  claim 13 , wherein the set of recommended nudging vectors comprises nudging vectors that cause the respective wells to avoid an obstacle. 
     
     
         18 . A non-transitory computer readable medium comprising computer executable code stored thereon, the computer executable code comprising:
 code for obtaining, by one or more processors, a respective nudge position for each of a plurality of wells;   code for determining, by the one or more processors, a zone of uncertainty for each of the plurality of wells, wherein each zone of uncertainty comprises a range of potential deviated locations for a location of a borehole of the respective well;   code for determining, by the one or more processors, based on the respective zone of uncertainty, a plurality of separation factors for each respective well;   code for determining, by the one or more processors, a minimum separation factor for each respective well from the respective plurality of separation factors;   code for comparing the respective minimum separation factor for each respective well to a threshold; and   code for storing or updating, by the one or more processors, in a memory, the respective nudge position for each respective well based on the comparison; and   code for outputting, by the one or more processors, a set of recommended nudging vectors, from the stored or updated nudge positions, to a display.   
     
     
         19 . The non-transitory computer readable medium of  claim 18 , wherein the code for storing or updating, by the one or more processors, in the memory, the respective nudge position for each respective well based on the comparison comprising code for storing the respective nudge position when the respective minimum separation factor for the respective well is at or above the threshold. 
     
     
         20 . The non-transitory computer readable medium of  claim 18 , wherein the code for storing or updating, by the one or more processors, in the memory, the respective nudge position for each respective well based on the comparison comprises code for updating the respective nudge position when the respective minimum separation factor for the respective well is below the threshold.