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

Claim 8:
9. 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 at said surface location,
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,
wherein said plurality of segments is comprised of a first segment having a first segment length and a second segment having a second segment length, and
wherein the step of extending is comprised of the following steps:
Step A1: setting said drill bit at an initial location (K), said bit location being at said initial location K, said downhole location being at a K−S location;
Step B1: 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 C1: 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 D1: 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 E1: moving said drill bit to a location (K+said first segment length) in the borehole according to the projection of Step D1, said bit location being at said location (K+said first segment length), said downhole location being at a (K−S+said first segment length) location,
Step F1: measuring with said surface location sensor at said surface location for said bit location at said location (K+said first segment length) so as to determine a location (K+said first segment length) surface sensor measurement;
Step G1: measuring with said downhole sensor at said downhole location for said bit location at said location (K+said first segment length) so as to determine a location (K−S+said first segment length) downhole sensor measurement;
Step H1: applying a first level adjusted Kalman filter to said location (K+said first segment length) surface sensor measurement and said location (K−S+said first segment length) 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+said first segment length) surface sensor measurement, and said location (K−S) downhole sensor measurement;
Step I1: moving said drill bit to said location (K+said first segment length+said second segment length) in the borehole according to the first adjusted projection of Step H1 when (K+said first segment length+said second segment length) is equal to (K+S), said bit location being at said location (K+said first segment length+said second segment length), said downhole location being at said (K) location when (K+said first segment length+said second segment length) is equal to (K+S);
Step J1: 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 K1: 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 L1: 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+said first segment length) 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 M1: moving said drill bit to a location (K+S+said first segment length) in the borehole according to the second level adjusted error correction of Step L1, said bit location 26 being at said location (K+S+said first segment length), said downhole location being at said (K+said first segment length) location,
Step N1: measuring with said surface location sensor at said surface location for said bit location at said location (K+S+said first segment length) so as to determine a location (K+S+said first segment length) surface sensor measurement;
Step O1: measuring with said downhole sensor at said downhole location for said bit location at said location (K+said first segment length) so as to determine a location (K+said first segment length) downhole sensor measurement; and
Step P1: applying a third level adjusted Kalman filter to said location (K+S+said first segment length) surface sensor measurement and said location (K+said first segment length) downhole sensor measurement, 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+said first segment length) surface sensor measurement, said location (K+S) surface sensor measurement, said location (K+S+said first segment length) surface sensor measurement, said location (K−S) downhole sensor measurement, said location (K) downhole sensor measurement, and said location (K+said first segment length) downhole sensor measurement.