Use of dual density spacer fluids to improve cementing efficiency in horizontal wellbores
First Claim
1. A well completion process for improved cement placement in a horizontal wellbore located in a formation comprising:
- a) circulating a cleaning fluid down the wellbore in an amount and for a time sufficient to condition and clean it for cementing a production tubing or casing in place;
b) directing a production tubing with centralizers therearound into the wellbore thereby locating the tubing centrally within the wellbore;
c) directing a first cement spacer fluid of a known density down an annulus formed between the tubing and wellbore so as to substantially clean-out the wellbore;
d) ceasing the introduction of the first cement spacer fluid down said annulus thereby allowing said first cement spacer fluid to equilibrate;
e) introducing into said annulus a second cement spacer fluid having a specific gravity of at least 0.1 less than the specific gravity of said first cement spacer fluid whereby said second cement spacer fluid overrides said first spacer fluid so as to contact contaminants in the top section of said annulus while said first fluid contacts contaminants in the bottom section of said annulus;
f) ceasing the introduction of said second cement spacer fluid into the annulus and allowing both fluids to equilibrate;
g) removing both cement spacer fluids containing said contaminants from said wellbore thereby cleaning said annulus;
h) directing a first cement slurry down the annulus and up the tubing which cement slurry has a density greater than the cement spacer fluid and is in an amount sufficient to fill the annulus; and
i) directing a second cement slurry down the annulus which cement slurry has a density less than the density of the first cement slurry and which overrides the first cement slurry thereby filling any voids that were unfilled by the first cement slurry so as to effectively isolate the casing from the formation.
2 Assignments
0 Petitions
Accused Products
Abstract
A well completion process for improved cement placement in a horizontal wellbore. Initially, a cleaning fluid is circulated down the wellbore for conditioning and cleaning it. Afterwards, a production tube containing centralizers is positioned centrally within the wellbore. Next, "spacer fluids" of higher and lower densities are circulated within an annulus formed by the space between the tube and the wellbore so as to more substantially clean the annulus out. Subsequently, a cement having a density greater than the spacer fluid is pumped into the annulus. Thereafter, a light weight cement is pumped into the annulus thereby overriding the heavier cement and removing voids in the annulus resulting in more efficient cement placement.
26 Citations
11 Claims
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1. A well completion process for improved cement placement in a horizontal wellbore located in a formation comprising:
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a) circulating a cleaning fluid down the wellbore in an amount and for a time sufficient to condition and clean it for cementing a production tubing or casing in place; b) directing a production tubing with centralizers therearound into the wellbore thereby locating the tubing centrally within the wellbore; c) directing a first cement spacer fluid of a known density down an annulus formed between the tubing and wellbore so as to substantially clean-out the wellbore; d) ceasing the introduction of the first cement spacer fluid down said annulus thereby allowing said first cement spacer fluid to equilibrate; e) introducing into said annulus a second cement spacer fluid having a specific gravity of at least 0.1 less than the specific gravity of said first cement spacer fluid whereby said second cement spacer fluid overrides said first spacer fluid so as to contact contaminants in the top section of said annulus while said first fluid contacts contaminants in the bottom section of said annulus; f) ceasing the introduction of said second cement spacer fluid into the annulus and allowing both fluids to equilibrate; g) removing both cement spacer fluids containing said contaminants from said wellbore thereby cleaning said annulus; h) directing a first cement slurry down the annulus and up the tubing which cement slurry has a density greater than the cement spacer fluid and is in an amount sufficient to fill the annulus; and i) directing a second cement slurry down the annulus which cement slurry has a density less than the density of the first cement slurry and which overrides the first cement slurry thereby filling any voids that were unfilled by the first cement slurry so as to effectively isolate the casing from the formation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification