Closed loop control of drilling toolface
Abstract
A downhole closed loop method for controlling a drilling toolface includes measuring first and second attitudes of the subterranean borehole at corresponding first and second upper and lower survey stations. The first and second attitudes are processed downhole while drilling to compute an angle change of the subterranean borehole between the upper and lower survey stations. The computed angle change is compared with a predetermined threshold. This process may be continuously repeated while the angle change is less than the threshold. The first and second attitudes are further processed downhole to compute a toolface angle when the angle change of the subterranean borehole is greater than or equal to the threshold. The toolface angle may then be further processed to control a direction of drilling of the subterranean borehole.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1 . A downhole steering tool comprising:
a downhole steering tool body; a steering mechanism for controlling a direction of drilling a subterranean borehole; sensors for measuring an attitude of the subterranean borehole; and a downhole controller including one or more modules having instructions to (i) process attitude measurements received from the sensors at a first survey station and a second survey station to compute an angle change between the first survey station and the second survey station and (ii) process the angle change to compute a rate of penetration while drilling.
2 . The downhole steering tool of claim 1 , wherein the rate of penetration while drilling is computed using the following mathematical equation:
R
O
P
=
β
Δt
·
DLS
where ROP represents the rate of penetration of drilling, DLS represents a dogleg severity of the subterranean borehole being drilled in (a), β represents the angle change between the upper and lower survey stations, and Δt represents a time passed between measuring the reference attitude and the measured attitude at the upper and lower survey stations.
3 . The downhole steering tool of claim 2 , wherein the one or more modules further have instructions to compute the rate of penetration substantially continuously while drilling.
4 . The downhole steering tool of claim 1 , wherein the angle change of the subterranean borehole is computed processed using one or more of the following mathematical equations:
β
=
(
Inc
low
-
Inc
u
p
)
2
+
sin
2
(
Inc
u
p
)
(
A
z
i
low
-
A
z
i
u
p
)
2
;
β
=
(
Inc
low
-
Inc
u
p
)
2
+
sin
2
(
Inc
low
)
(
A
z
i
l
o
w
-
A
z
i
u
p
)
2
;
or
β
=
(
Inc
low
-
Inc
u
p
)
2
+
sin
(
Inc
low
)
sin
(
Inc
u
p
)
(
A
z
i
low
-
A
z
i
u
p
)
2
;
where β represents the angle change of the subterranean borehole, Inc low and Azi low represent the measured attitude at the lower survey station, and Inc up and Azi up represent the reference attitude at the upper survey station.
5 . The downhole steering tool of claim 1 , wherein the angle change of the subterranean borehole is processed using one or more of the following mathematical equations:
β
=
(
Inc
l
o
w
-
Inc
u
p
)
2
+
A
W
sin
2
(
Inc
u
p
)
(
A
z
i
l
o
w
-
A
z
i
u
p
)
2
;
β
=
(
Inc
l
o
w
-
Inc
u
p
)
2
+
A
W
sin
2
(
Inc
l
o
w
)
(
A
z
i
l
o
w
-
A
z
i
u
p
)
2
;
or
β
=
(
Inc
l
o
w
-
Inc
u
p
)
2
+
AW
sin
(
Inc
l
o
w
)
sin
(
Inc
u
p
)
(
A
z
i
l
o
w
-
A
z
i
u
p
)
2
;
where β represents the angle change of the subterranean borehole, Inc low and Azi low represent the measured attitude at the lower survey station, and Inc up and Azi up represent the reference attitude at the upper survey station, and AW represents a weighting factor in a range from 0 to 1.
6 . The downhole steering tool of claim 5 , where AW is in a range from about 0.1 to about 0.5.Cited by (0)
No later patents cite this yet.
References (0)
No backward citations on record.