Use of marker fluid in cementing offshore wells
AssigneeUnion Oil Company of California
InventorJulius P. Gallus
Life of this patent
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Abstract
Cementing casing in an offshore well by displacing a drilling fluid with a settable cement slurry wherein there is injected into the annulus between the sidewall of the well and the casing ahead of the cement slurry a slug of a visually identifiable marker fluid containing cement, water, particulate carbon black, coal dust, and a surface active agent; visually observing when the fluid being displaced from the annulus changes from drilling fluid to marker fluid, and shutting in the well to allow the cement slurry to set.
Claims12
Method for cementing casing in an offshore well completed under water comprising sequentially:
- (a) drilling a borehole,
- (b) positioning a drilling fluid in the borehole,
- (c) positioning one or more connected sections of casing in the borehole,
- (d) injecting into the casing, out the bottom thereof, up the annular space between the casing and the borehole and out into the surrounding water a slug of about 2 to 20 barrels of a black colored marker fluid comprising:
- [1] 100 parts by weight cement;
- [2] about 35 to 56 parts by weight water,
- [3] about 5 to 8 parts by weight particulate carbon black,
- [4] about 4 to 6.4 parts by weight coal dust, and
- [5] about 0.52 to 0.84 parts by weight surface active agent,
- (e) injecting into the casing via the same route a cement slurry,
- (f) observing the displaced fluid emerging into the surrounding water from the annular space,
- (g) observing when the black colored marker fluid begins to emerge from the annular space,
- (h) removing the cement slurry from the casing, and
- (i) shutting in the well for sufficient time to allow the cement slurry to set.
Method for cementing casing in an offshore well completed under water comprising sequentially:
- (a) drilling a borehole,
- (b) positioning a drilling fluid in the borehole,
- (c) positioning one or more connected sections of casing in the borehole,
- (d) injecting into the casing, out the bottom thereof, up the annular space between the casing and the borehole and out into the surrounding water a slug of about 2 to 20 barrels of a black colored marker fluid comprising:
- [1] 332 parts by weight cement slurry,
- [2] about 17 to 175 parts by weight water,
- [3] about 2.5 to 20 parts by weight particulate carbon black,
- [4] about 2 to 15 parts by weight coal dust, and
- [5] about 0.2 to 6 parts by weight surface active agent,
- (e) injecting into the casing via the same route a cement slurry,
- (f) observing the displaced fluid emerging into the surrounding water from the annular space,
- (g) observing when the black colored marker fluid begins to emerge from the annular space,
- (h) removing the cement slurry from the casing, and
- (i) shutting in the well for sufficient time to allow the cement slurry to set.
Dependencies are inferred from the claim text.