Patent ID: 11952881
Assignee: NORALIS LIMITED
Field: Civil engineering (Other fields)
Classification: CPC E | IPC E

Claim 0:
1. A method for drilling, comprising steps of:
extending a borehole from a surface location to a borehole end with a drill string being comprised of a bottom hole assembly with a drill bit,
wherein the drill bit is positioned on the bottom hole assembly at said borehole end so as to set a bit location,
wherein said surface location is comprised of a surface sensor,
wherein said bottom hole assembly is comprised of a downhole sensor at a downhole location,
wherein said downhole sensor is separated by a plurality of segments from said bit location,
wherein said plurality of said segments has a length S, said bit location and said downhole locations being separated by said length S,
wherein each segment has a segment length s less than said length, and
wherein the step of extending is comprised of following steps:
Step A: setting said drill bit at an initial location (K) in the borehole, said bit location being at said initial location K, said downhole location being at a K−S location;
Step B: measuring with said surface sensor at said surface location for said bit location at said initial location (K) so as to determine an initial location (K) surface sensor measurement;
Step C: measuring with said downhole sensor at said downhole location for said bit location at said initial location (K) so as to determine a location (K−S) downhole sensor measurement;
Step D: applying an initial Kalman filter to said initial location (K) surface sensor measurement and said location (K−S) downhole sensor measurement, so as to generate a projection of said borehole end for steering said drill bit,
wherein said initial Kalman filter is comprised of an initial error correction based on said initial location (K) surface sensor measurement and said location (K−S) downhole sensor measurement;
Step E: moving said drill bit to a location (K+(n)s) in the borehole according to the projection of Step D, said bit location being at said location (K+(n)s), said downhole location being at a (K−S+(n)s) location,
wherein n is a positive integer;
Step F: measuring with said surface location sensor at said surface location for said bit location at said location (K+(n)s) so as to determine a location (K+(n)s) surface sensor measurement;
Step G: measuring with said downhole sensor at said downhole location for said bit location at said location (K+(n)s) so as to determine a location (K−S+(n)s) downhole sensor measurement;
Step H: applying a first level adjusted Kalman filter to said location (K+(n)s) surface sensor measurement and said location (K−S+(n)s) downhole sensor measurement, so as to generate a first level adjusted projection of said borehole end for steering said drill bit,
wherein said first level adjusted Kalman filter is comprised of a first level adjusted error correction based on said initial location (K) surface sensor measurement, said location (K+(n)s) surface sensor measurement, and said location (K−S) downhole sensor measurement;
Step I: repeating the Steps E-H until (n)s is equal to S, wherein said projection of Step D is replaced with a corresponding first level adjusted projection of a respective Step H during a subsequent step of repeating Step E;
Step J: moving said drill bit to said location (K+(n)s) in the borehole according to the corresponding first level adjusted projection of the respective repeated Step H when (K+(n)s) is equal to (K+S), said bit location being at said location (K+(n)s), said downhole location being at said (K−S+(n)s) location when (K−S+(n)s) is equal to (K);
Step K: measuring with said surface location sensor at said surface location for said bit location at said location (K+S) so as to determine a location (K+S) surface sensor measurement;
Step L: measuring with said downhole sensor at said downhole location for said bit location at said location (K) so as to determine a location (K) downhole sensor measurement;
Step M: applying a second level adjusted Kalman filter to said location (K+S) surface sensor measurement and said location (K) downhole sensor measurement, so as to generate a second level adjusted projection of said borehole end for steering said drill bit,
wherein said second level adjusted Kalman filter is comprised of a second level adjusted error correction based on said initial location (K) surface sensor measurement, said location (K+(n)s) surface sensor measurement, said location (K+S) surface sensor measurement, said location (K−S) downhole sensor measurement and said location (K) downhole sensor measurement;
Step N: moving said drill bit to a location (K+S+(z)s) in the borehole according to the second level adjusted projection of Step M, said bit location 26 being at said location (K+S+(z)s), said downhole location being at said (K+(z)s) location,
wherein z is a positive integer;
Step O: measuring with said surface location sensor at said surface location for said bit location at said location (K+S+(z)s) so as to determine a location (K+S+(z)s) surface sensor measurement;
Step P: measuring with said downhole sensor at said downhole location for said bit location at said location (K+(z)s) so as to determine a location (K+(z)s) downhole sensor measurement;
Step Q: applying a third level adjusted Kalman filter to said location (K+S+(z)s) surface sensor measurement and said location (K+(z)s) downhole sensor measurement, when z is equal to n, so as to generate a third level adjusted projection of said borehole end for steering said drill bit,
wherein said third level adjusted Kalman filter is comprised of a third level adjusted error correction based on said initial location (K) surface sensor measurement, said location (K+(n)s) surface sensor measurement, said location (K+S) surface sensor measurement, said location (K+S+(z)s) surface sensor measurement, said location (K−S) downhole sensor measurement, said location (K−S+(n)s) downhole sensor measurement, said location (K) downhole sensor measurement, and said location (K+(z)s) downhole sensor measurement;
repeating the Steps N-Q for completing the borehole, wherein the second level adjusted projection of Step M is replaced with a corresponding third adjusted projection of a respective Step Q during the step of repeating Step N.