Whipstock for use with a mill bit including varying material removal rates
Provided is a whipstock and well system. The whipstock, in one aspect, includes a coupling section having a first radius of curvature, the coupling section configured to engage with a mill bit when running in hole. The whipstock, in accordance with this aspect, further includes a casing breakthrough section having a second radius of curvature, and a controlled exit section having a third radius of curvature, wherein the second radius of curvature is less than the third radius of curvature.
1. A whipstock, comprising:
a coupling section having a first radius of curvature, the coupling section configured to engage with a mill bit when running in hole;
a casing breakthrough section having a second radius of curvature; and
a controlled exit section having a third radius of curvature, wherein the second radius of curvature is less than the third radius of curvature, wherein the second radius of curvature is at least 5% less than the third radius of curvature.
2. The whipstock as recited in claim 1 , wherein the second radius of curvature is at least 10% less than the third radius of curvature.
3. The whipstock as recited in claim 1 , wherein the second radius of curvature is at least 25% less than the third radius of curvature.
4. The whipstock as recited in claim 1 , wherein the second radius of curvature is less than the first radius of curvature.
5. The whipstock as recited in claim 4 , wherein the third radius of curvature is less than the first radius of curvature.
6. The whipstock as recited in claim 1 , wherein the coupling section has a first ramp rate, the casing breakthrough section has a second ramp rate, and the controlled exit section has a third ramp rate.
7. The whipstock as recited in claim 6 , wherein the first ramp rate is less than the second ramp rate but greater than the third ramp rate.
8. The whipstock as recited in claim 7 , wherein the second ramp rate is at least six times the first ramp rate.
9. The whipstock as recited in claim 8 , wherein the controlled exit section includes a downhole portion with a downhole portion ramp rate and an uphole portion with an uphole portion ramp rate, and further wherein a downhole portion ramp rate is less than an uphole portion ramp rate.
10. A well system, comprising:
a wellbore extending through one or more subterranean formations;
wellbore casing located in at least a portion of the wellbore;
a whipstock located within the wellbore radially inside of the wellbore casing, the whipstock including:
a coupling section having a first radius of curvature, the coupling section configured to engage with a mill bit when running in hole;
a casing breakthrough section having a second radius of curvature; and
a controlled exit section having a third radius of curvature, wherein the second radius of curvature is less than the third radius of curvature, wherein the second radius of curvature is at least 5% less than the third radius of curvature; and
a bottom hole assembly extending within the wellbore adjacent the whipstock.
11. The well system as recited in claim 10 , wherein the second radius of curvature is at least 10% less than the third radius of curvature.
12. The well system as recited in claim 10 , wherein the second radius of curvature is at least 25% less than the third radius of curvature.
13. The well system as recited in claim 10 , wherein the second radius of curvature is less than the first radius of curvature.
14. The well system as recited in claim 13 , wherein the third radius of curvature is less than the first radius of curvature.
15. The well system as recited in claim 10 , wherein the coupling section has a first ramp rate, the casing breakthrough section has a second ramp rate, and the controlled exit section has a third ramp rate.
16. The well system as recited in claim 10 , wherein the first ramp rate is less than the second ramp rate but greater than the third ramp rate.
17. The well system as recited in claim 16 , wherein the second ramp rate is at least six times the first ramp rate.
18. The well system as recited in claim 17 , wherein the controlled exit section includes a downhole portion with a downhole portion ramp rate and an uphole portion with an uphole portion ramp rate, and further wherein a downhole portion ramp rate is less than an uphole portion ramp rate.
19. The well system as recited in claim 10 , further including a lateral wellbore extending from the wellbore proximate the whipstock.
20. The well system as recited in claim 10 , further including a mill bit located proximate the whipstock, the mill bit including:
a tubular having an uphole end and a downhole end;
a first cutting section having one or more first cutting surfaces disposed about the tubular, the first cutting section having a first material removal rate and configured to engage with wellbore casing disposed within a wellbore; and
a second cutting section having one or more second cutting surfaces disposed about the tubular, the second cutting section having a second material removal rate less than the first material removal rate and configured to engage with a whipstock disposed within the wellbore.