West Africa Operator Boosts Zonal Isolation in Horizontal Well

Published: 08/03/2020

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Optimize cementing across production zones

Poor cement bond logs across production zones in some offshore wells induced compromises in subsequent perforating and multistage stimulation operations. Conventional cementing technology was leaving channels of oil-based drilling fluid (OBM) in long (1,200-m) horizontal segments even when following cementing best practices for mud removal, centralization, and casing movement.

Improve spacer and centralization

As an initial step to improve the NAF removal and water-wetting of downhole surfaces, the operator used CemPRIME engineered chemistry spacer, which improved bond logs but still left channels where casing standoff is not optimal. Furthermore, the centralizer distribution was increased from an average of one per two joints to one per joint, but the result remained less than optimal.

Bond logs demonstrating improved zonal isolation in the well cemented using CemFIT Shield system.
Well A, top, cemented using CemFIT Shield system, has a much better bond log across all production zones, as compared with a neighboring well, bottom, cemented using conventional cement.
Bond logs demonstrating improved zonal isolation in the well cemented using CemFIT Shield system.

Interact with OBM to eliminate channeling

CemFIT Shield system improves zonal isolation in wells drilled with NAF, especially in a long horizontal well where limited casing standoff or inability to move casing impeded complete mud removal.

Achieve cement bonds to enable multistage stimulation

After extensive laboratory testing and blend characterization, Well A was cemented using CemFIT Shield system. Bond logs verified the high quality of the cement sheath across all of the production zones, a marked improvement as compared with a neighboring well cemented conventionally. The result enabled well perforation to proceed as designed, without compromises to accommodate the detrimental effects of channeling on subsequent multistage stimulation operations.

West Africa, Africa, Offshore

To improve zonal isolation in long horizontal offshore wells drilled with nonaqueous fluid (NAF), an operator in West Africa used CemFIT Shield mud-sealing cement system, achieving significantly better bond logs as compared with nearby wells cemented using conventional slurry at the same density.

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