TVD corrected geosteer
A method for determining a total vertical depth (TVD) for a well plan involves measuring differences between a projected BHA position at a depth of a survey station and a calculated BHA position based upon a minimum curvature method at the depth of the survey station. The differences are accumulated at each survey station with respect to the BHA position. Real time TVD corrected gamma logs are generated responsive to the accumulated differences of the BHA position.
1. A method for determining depths of wells, the method comprising:
determining a first projected location of a bottom hole assembly (BHA) at a first depth of a first survey station of a well being drilled, wherein the first projected location of the BHA is determined responsive to a plurality of sensor readings;
determining a second projected location of the BHA at the first depth using a minimum curvature method;
calculating a first difference between the first projected location of the BHA and the second projected location of the BHA;
determining a third projected location of the BHA at a second depth of a second survey station of the well, wherein the third projected location of the BHA is determined responsive to a plurality of sensor readings;
determining a fourth projected location of the BHA at the second depth using a minimum curvature method;
calculating a second difference between the third projected location of the BHA and the fourth projected location of the BHA;
accumulating the first and second differences, wherein each of the first and second differences correspond to each of a plurality of survey stations associated with the well;
correcting, without delay during drilling of the well, a first gamma log for the well based on the first and second differences, the first gamma log comprising a plurality of gamma radiation readings;
generating a true vertical depth (TVD)-corrected gamma log from the accumulated first and second differences; and
based on the TVD-corrected gamma log, controlling drilling of the well including modifying a drilling parameter used for drilling of the well.
2. The method of claim 1 , further comprising:
receiving a first measured value relating to a fifth projected location of the BHA in the well, the first measured value including at least one of an inclination reading and an azimuth reading; and
comparing the first measured value to a sixth projected location of the BHA that is projected between adjacent survey stations.
3. The method of claim 2 , further comprising:
mapping the sixth projected location of the BHA between the first and second survey stations responsive to the first measured value.
4. The method of claim 1 , further comprising:
locating the BHA at a fifth projected location of the BHA, wherein an accuracy of the fifth projected location of a BHA is improved based on the TVD-corrected gamma log.
5. The method of claim 1 , wherein the correcting further comprises:
determining at least one TVD of the BHA along the well.
6. The method of claim 5 , further comprising:
updating a well path shape between survey stations based on the TVD-corrected gamma log to improve an accuracy of the well path shape.
7. The method of claim 1 , further comprising:
determining a fifth projected location of the BHA at a third depth of the well responsive to another plurality of sensor readings, wherein the another plurality of sensor readings are obtained between successive survey stations along the well;
determining a sixth projected location of the BHA at the third depth using a minimum curvature method;
calculating a third difference between the fifth projected location of the BHA and the sixth projection location of the BHA;
accumulating the first, second, and third differences; and
correcting, without delay during drilling of the well, the first gamma log for the well based on the first, second, and third differences.
8. A method for determining depths of wells, the method comprising:
determining a first projected location of a bottom hole assembly (BHA) at a first depth of a first survey station of a well being drilled, wherein the first projected location is determined using (1) a true vertical depth (TVD); and (2) an azimuthal positioning of the BHA;
determining a second projected location of the BHA at the first depth using a minimum curvature method;
calculating a first difference between the first projected location of the BHA and the second projected location of the BHA;
determining a third projected location of the BHA at a second depth of the well responsive to a plurality of sensor readings, wherein the sensor readings are obtained between successive survey stations along the well;
determining a fourth projected location of the BHA at the second depth using a minimum curvature method;
calculating a second difference between the third projected location of the BHA and the fourth projected location of the BHA;
accumulating the first and second differences, wherein each of the first and second differences correspond to each of a plurality of survey stations associated with the well;
correcting, without delay during drilling of the well, a first gamma log for the well based on the first and second differences, the first gamma log comprising a plurality of gamma radiation readings;
generating a true vertical depth (TVD)-corrected gamma log from the accumulated first and second differences; and
based on the TVD-corrected gamma log, controlling drilling of the well including modifying a drilling parameter used for drilling of the well.
9. The method of claim 8 , further comprising:
receiving a first measured value relating to a fifth projected location of the BHA in the well, the first measured value including at least one of an inclination reading and an azimuth reading;
comparing the first measured value to a sixth projected location of the BHA that is projected between adjacent survey stations.
10. The method of claim 9 , further comprising:
mapping the sixth projected location of the BHA between the first and second survey stations responsive to the first measured value.
11. The method of claim 8 , further comprising:
determining a seventh projected location of the BHA, wherein an accuracy of the seventh projected location of the BHA is improved based on the TVD-corrected gamma log.
12. The method of claim 8 , wherein the correcting further comprises determining at least one true vertical depth TVD of the BHA along the well.
13. The method of claim 12 , further comprising:
updating a well path shape between adjacent survey stations based on the TVD-corrected gamma log to improve an accuracy of the well path shape.
14. The method of claim 8 , further comprising:
determining a fifth projected location of the BHA at a third depth of a second survey station of the well, wherein the fifth projected location of the BHA is determined responsive to a plurality of sensor readings;
determining a sixth projected location of the BHA at the third depth using a minimum curvature method;
calculating a third difference between the fifth projected location of the BHA and the sixth projection location of the BHA;
accumulating the first, second, and third differences; and
correcting, without delay during drilling of the well, the first gamma log for the well based on the first, second, and third differences.
15. A system for determining depths of wells, the system comprising:
a processor;
a memory coupled to the processor and storing a plurality of instructions executable by the processor, the instructions including instructions for:
determining a first projected location of a bottom hole assembly (BHA) at a first depth of a first survey station of a well being drilled, wherein the first projected location of the BHA is determined responsive to a plurality of sensor readings;
determining a second projected location of the BHA at the first depth using a minimum curvature method;
calculating a first difference between the first projected location of the BHA and the second projected location of the BHA;
determining a third projected location of the BHA at a second depth along the well and after the first survey station but before the next survey station, wherein the third projected location of the BHA is determined responsive to a plurality of sensor readings;
determining a fourth projected location of the BHA at the second depth using a minimum curvature method;
calculating a second difference between the third projected location of the BHA and the fourth projected location of the BHA;
accumulating the first and second differences;
correcting, without delay during drilling of the well, a first gamma log for the well based on the first and second differences, the first gamma log comprising a plurality of gamma radiation readings;
generating a true vertical depth (TVD)-corrected gamma log from the accumulated first and second differences; and
based on the TVD-corrected gamma log, controlling drilling of the well including modifying a drilling parameter used for drilling of the well.
16. The system of claim 15 , further comprising instructions for:
receiving a first measured value relating to a fifth projected location of the BHA in the well, the first measured value including at least one of an inclination reading and an azimuth reading; and
comparing the first measured value to a sixth projected location of the BHA that is projected between adjacent survey stations.
17. The system of claim 16 , further comprising instructions for:
mapping the sixth projected location of the BHA between the first and second adjacent survey stations responsive to the first measured value.
18. The system of claim 15 , further comprising instructions for:
locating the BHA at a seventh projected location of the BHA, wherein an accuracy of the seventh projected location of the BHA is improved based on the TVD-corrected gamma log.
19. The system of claim 15 , wherein the instructions for correcting further comprise instructions for:
determining at least one TVD of the BHA along the well.
20. The system of claim 15 , further comprising instructions for:
updating a well path shape between adjacent survey stations based on the TVD-corrected gamma log to improve an accuracy of the well path shape.