Well bore cleaning
A system and method for drilling a substantially horizontal well bore in a normally to sub-normally pressured formation. The normally to sub-normally pressured formation is an unconventional reservoir. The well bore is drilled over-balanced with a drilling fluid having a density at least about the density of the cuttings produced by drilling the well bore.
1 . A method for drilling a well bore, comprising:
drilling a substantially horizontal well bore in a normally to sub-normally pressured formation, the normally to sub-normally pressured formation comprising an unconventional reservoir; and
drilling the well bore over-balanced with a drilling fluid comprising a density greater than 9.5 pounds per gallon.
2 . The method of claim 1 , wherein the drilling fluid comprises a density at or greater than 10 pounds per gallon.
3 . The method of claim 1 , the drilling fluid comprising a density substantially at that of the cuttings produced by drilling the well bore.
4 . The method of claim 3 , wherein drilling the substantially horizontal well bore is performed at a rate that is greater than if the drilling fluid had a density substantially less than that of the cuttings produced by drilling the well bore.
5 . The method of claim 1 , further comprising adjusting at least one of the flow rate and the properties of the drilling fluid based at least in part on a difference between an actual amount of cuttings recovery per unit time and an expected amount of cuttings recovery per unit time.
6 . The method of claim 1 , wherein the unconventional reservoir comprises a coal bed.
7 . The method of claim 1 , wherein the unconventional reservoir comprises a shale.
8 . The method of claim 1 , wherein the unconventional reservoir comprises at least one of naturally occurring fractures and cleats.
9 . A system for drilling a well bore, comprising:
a drill bit coupled by a drill string to a rig at a surface, the drill bit operable to drill a horizontal well bore in a normally to sub-normally pressured formation, the normally to sub-normally pressured formation comprising an unconventional reservoir; and
a drilling fluid pumped through the drill string to the drill bit and recirculated to the surface through the well bore, the drilling fluid comprising a density greater than 9.5 pounds per gallon.
10 . The system of claim 9 , wherein the drilling fluid comprises a density at least 10 pounds per gallon.
11 . The system of claim 9 , wherein the drilling fluid comprises a density substantially at that of the cuttings produced by drilling the well bore.
12 . The system of claim 9 , wherein the drilling fluid further comprises a viscosity agent.
13 . The system of claim 9 , wherein the drilling fluid further comprises at least one of micelles and aphrons.
14 . The system of claim 9 , wherein the unconventional reservoir comprises a coal seam.
15 . The system of claim 9 , wherein the unconventional reservoir comprises a shale.
16 . The system of claim 9 , wherein the unconventional reservoir comprises at least one of naturally occurring fractures and cleats.
17 . The system of claim 9 , wherein the drilling fluid comprises FLC 2000.
18 . The system of claim 17 , wherein the drilling fluid further comprises starch.
19 . The system of claim 9 , wherein the drilling fluid is adapted to form a filter cake to seal the well bore in the normally to sub-normally pressured formation during drilling.
20 . A method for drilling a well bore, comprising:
drilling a substantially horizontal well bore in a normally to sub-normally pressured formation, the normally to sub-normally pressured formation comprising an unconventional reservoir; and
drilling the well bore over-balanced with a drilling fluid comprising a density at least about the density of the cuttings produced by drilling the well bore.
21 . The method of claim 20 , wherein the drilling fluid comprises a density greater than 9.5 pounds per gallon.
22 . The method of claim 20 , wherein the drilling fluid comprises a density at or greater than 10 pounds per gallon.
23 . The method of claim 20 , wherein the reservoir comprises a coal seam.
24 . The method of claim 20 , wherein drilling the substantially horizontal well bore is performed at a rate that is greater than if the drilling fluid had a density substantially less than that of the cuttings produced by drilling the well bore.
25 . The method of claim 20 , further comprising adjusting at least one of the flow rate and the properties of the drilling fluid based at least in part on a difference between an actual amount of cuttings recovery per unit time and an expected amount of cuttings recovery per unit time.
26 . The method of claim 20 , wherein the unconventional reservoir comprises at least one of naturally occurring fractures and cleats.
27 . The method of claim 20 , wherein the drilling fluid comprises FLC 2000.
28 . The method of claim 1 , wherein the drilling fluid comprises FLC 2000.