In an Offshore field, off the coast of Abu Dhabi, well integrity objectives are becoming more difficult to achieve as open hole sections become deeper, laterally longer and more highly deviated. In this mature field, one of the main challenges of well construction is successfully cementing long production-casing strings covering multiple reservoirs across the 8½-in sections. This paper describes some of the techniques and best practices that were applied on these wells to achieve the required zonal isolation.

Achieving zonal isolation across multiple reservoirs through a single or multi-lateral configuration is a major challenge in this field. The reservoir formation is porous and requires a special gas tight design or impermeable cement system. Inadequate hole cleaning due to poor standoff attributed to complex well design is another main limitation, resulting in insufficient mud removal leading to an uneven cement distribution around the casing. Additionally multiple pressure-testing cycles are required post cement-setting and during the completion phase, a practice that can destabilize the cement system causing it to fail. Moreover, controlling loss circulation while running or after landing casing is another challenge in this field.

To overcome these challenges a series of customized improvements were applied subsequently through continuous improvement and implementing lessons learnt from previous operations. The elements of this approach included introducing higher density cement systems to cover the horizontal sections, while retaining the ECD within the required margins. Another element utilized was that of two cement slurries; Lead and tail, which were designed to achieve controlled ECD. An additional element which was also implemented addressed enhancing the flexible expandable gas tight slurry by adding Latex to achieve a fit for purpose solution. The last element of this strategy included improving hole cleaning and mud removal efficiency by optimizing spacer design and volumes in addition to the loss circulation additives in the spacer systems.

Throughout the operation, the cement jobs were executed successfully with no losses. Cement jobs were evaluated through running job design simulation Vs execution parameters comparison. The approach resulted in substantial improvement on log responses. Additionally, after implementing the approach, logs were compared to offset wells from the same field to track the improvement done.

The paper reviews enhanced practices implemented to overcome challenges faced during well cementing. Being able to find a solution to this complex problem, delivering a comprehensive cement quality, and improving cementing integrity on these wells resulted in expanding this approach to the rest of the fields. The improvement measures that were developed are now being adopted across all jobs to yield a similar outcome.

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