Drilling speed and depth computation for downhole tools
A method for managing a drilling operation includes generating, by a first sensor and a second sensor of a bottom hole assembly (BHA), a first time based data log and a second time based data log representing a borehole parameter along a drilling trajectory. A time shift is determined by comparing the first time based data log and the second time based data log. The time shift is processed along with an axial distance between the sensors to compute a rate of penetration.
1. A method for determining a rate of penetration of drilling of a subterranean well, the method comprising:
(a) acquiring a first data log using a first sensor in a bottom hole assembly;
(b) acquiring a second data log using a second sensor in the bottom hole assembly;
(c) causing a downhole processor to correlate the first and second data logs to compute a time shift;
(d) causing the downhole processor to process the time shift computed in (c) and an axial distance between the first and second sensors on the bottom hole assembly to compute the rate of penetration; and
(e) adjusting a drilling operation based on the rate of penetration computed in (d).
2. The method of claim 1 , further comprising:
(f) causing the downhole processor to integrate the rate of penetration to compute a downhole measured depth.
3. The method of claim 2 , further comprising:
(g) receiving a surface measured depth at the downhole processor via a downlink from a surface location; and
(h) causing the downhole processor to calibrate the downhole measured depth computed in (f) using the surface measured depth received in (g).
4. The method of claim 1 , further comprising:
(i) causing the downhole processor to process the rate of penetration computed in (d) to further compute at least one drilling parameter selected from the group consisting of build rate, turn rate, dogleg severity, and gravity toolface.
5. The method of claim 4 , further comprising:
(j) causing the downhole processor to process the rate of penetration and the at least one drilling parameter to compute a toolface and a steering ratio of a steering tool.
6. The method of claim 1 , further comprising:
(k) transmitting the rate of penetration to a surface location; and
(l) comparing the rate of penetration with a surface derived rate of penetration.
7. The method of claim 1 , wherein the first data log and the second data long are obtained simultaneously in (a) and (b) while drilling the subterranean wellbore.
8. The method of claim 1 , wherein first sensor and the second sensor comprise a navigation sensor, a formation evaluation sensor, a fluid sampling sensor, a pressure sensor, a temperature sensor, a downhole camera, or a caliper sensor.
9. The method of claim 1 , wherein the time shift is computed in (c) by maximizing a correlation factor.
10. The method of claim 1 , wherein the time shift is computed in (c) using at least one of the following mathematical equations:
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Y
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and
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;
wherein Σ represents a summation over N time points in the first data log, T represents one of the N time points, t represents the time shift, X[T] represents a first normalized value of the first data log at T, and Y[T−t] represents a second normalized value of the second data log at T−t.
11. The method of claim 1 , wherein the rate of penetration is computed in (d) by dividing the axial distance by the time shift.
12. The method of claim 1 , further comprising:
(m) acquiring a third data log using a third sensor in the bottom hole assembly;
(n) acquiring a fourth data log using a fourth sensor in the bottom hole assembly;
(o) causing a downhole processor to correlate the third and fourth data logs to compute a second time shift;
(p) causing the downhole processor to process the second time shift computed in (o) and an axial distance between the third and fourth sensors on the bottom hole assembly to compute a second rate of penetration; and
(q) causing the downhole processor to compare the rate of penetration computed in (d) and the second rate of penetration computed in (p).
13. The method of claim 12 , wherein the first and second sensors comprise formation evaluation sensors and the third and fourth sensors comprise navigation sensors.
14. A bottom hole assembly comprising:
first and second axially spaced apart sensors; and
a rate of penetration computation module configured to: (i) process a correlation of a first data log obtained from the first sensor and a second data log obtained from the second sensor to compute a time shift, and (ii) process the time shift and an axial distance between the first and second sensors to compute a rate of penetration of drilling, wherein the time shift is computed in (i) by maximizing a correlation factor.
15. The bottom hole assembly of claim 14 , further comprising:
a drilling parameter computation module configured to process the rate of penetration to further compute at least one drilling parameter selected from the group consisting of build rate, turn rate, dogleg severity, and gravity toolface.
16. The bottom hole assembly of claim 15 , wherein the drilling parameter computation module is further configured to process the rate of penetration and the at least one drilling parameter to compute a toolface and a steering ratio of a steering tool.
17. A method for determining a rate of penetration of drilling of a subterranean well, the method comprising:
(a) simultaneously acquiring first and second data logs while drilling using corresponding first and second sensors deployed in a bottom hole assembly;
(b) causing a downhole processor to correlate the first and second data logs to compute a time shift;
(c) causing the downhole processor to process the time shift computed in (b) and an axial distance between the first and second sensors on the bottom hole assembly to compute the rate of penetration;
(d) causing the downhole processor to process the rate of penetration computed in (c) to further compute at least one drilling parameter selected from the group consisting of build rate, turn rate, dogleg severity, and gravity toolface;
(e) causing the downhole processor to process the rate of penetration and the at least one drilling parameter to compute a toolface and a steering ratio of a steering tool; and
(f) applying the toolface and steering ratio to the steering tool while drilling.
18. The method of claim 17 , wherein the method further comprises adjusting a drilling operation based on the rate of penetration computed in (c).
19. The method of claim 17 , wherein the method further comprises computing the time shift in (b) by maximizing a correlation factor.