…Restoring Peak Performance in Nigeria’s AX Field

As global offshore oil and gas operations face increasing challenges in maximizing production efficiency, one engineer has emerged at the forefront of technical innovation in Nigeria’s deepwater sector. Lawani Raymond, an accomplished well stimulation expert at Schlumberger (SLB), has been instrumental in the successful recovery of performance in one of Nigeria’s key offshore injector wells—the AX9 horizontal injector. His leadership and precision planning were pivotal in overcoming the operational hurdles associated with injectivity decline, delivering outstanding results for the field.

The breakthrough was showcased at the Society of Petroleum Engineers’ (SPE) Nigeria Annual International Conference and Exhibition, where the collaborative team highlighted the well stimulation’s significant impact on restoring injectivity, reducing operational risks, and enhancing long-term field output.
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Tackling Declining Injectivity in Offshore Nigeria
Located in a prolific turbidite reservoir offshore Nigeria, the AX field is characterized by high-permeability, unconsolidated sands. Initially, deviated frac-pack injectors were used to maintain reservoir pressure, but these wells frequently experienced injectivity decline due to fines migration and other formation damage mechanisms.

Recognizing the limitations of traditional approaches, Lawani Raymond and the project team shifted focus to horizontal injectors, offering larger flow areas and lower velocities to mitigate sand production risks. However, the AX9 well, despite its horizontal design, showed signs of performance deterioration, with injectivity falling drastically from 40,000 barrels of water per day (kbwpd) to 21 kbwpd over time.

“The challenge was clear,” Raymond explained. “We needed a proactive intervention that could address formation damage while ensuring long-term well integrity.”

Diagnosing Formation Damage: A Technical Approach
The team employed advanced surveillance techniques, including Hall plot analysis, to confirm that injectivity decline was caused by internal formation damage rather than wellbore restrictions. Mineralogical analysis revealed the presence of fines-prone clays such as Smectite, Illite, and Kaolinite, which contributed to plugging and injectivity impairment.

Lawani Raymond’s role was central in designing a stimulation strategy tailored to AX9’s specific reservoir characteristics. His technical insight emphasized early intervention while the well was still operating in matrix mode, ensuring maximum benefit from the stimulation process.

Precision Stimulation: Engineering Execution Excellence
Under Raymond’s leadership, the team developed a matrix acid stimulation plan utilizing a nitrified mud acid system with continuous foam diversion. This innovative approach was selected based on its proven success in similar offshore fields but carefully customized for the AX9 formation.

To ensure seamless execution, Raymond coordinated all aspects of the operation, from pre-loadout checks to equipment mobilization. High-pressure nitrogen units, fluid pumps, IWOCS systems, and other critical components were prepared meticulously, reflecting Schlumberger’s stringent safety and quality assurance standards.

The treatment sequence involved multiple stages, including ammonium chloride pre-flushes, acid pre-flushes, a main stage of 13.5:1.5 mud acid, and post-flushes—all supported by nitrogen foaming to ensure even acid distribution and effective fines removal.

“We left no room for error,” Raymond commented. “Every phase of the operation was planned to minimize risk, ensure safety, and maximize well productivity.”

Record-Breaking Results: Restored Injectivity and Production
The stimulation operation proceeded without a single incident, completing over 624 minutes of pumping time safely and efficiently. Post-treatment evaluations revealed remarkable improvements: the injection rate surged back to 43 kbwpd, with a substantial pressure drop of 21% and the injectivity index (II) soaring from 20 to over 80-100 bpd/psi.

This restoration of injectivity not only improved water injection but also unlocked an estimated 5,000 barrels per day in incremental oil production from the connected producers.

Reflecting on the success, Lawani Raymond emphasized the importance of strategic timing, stating, “Stimulating early, before the well transitions to frac mode, allowed us to preserve the reservoir’s integrity and extend the injector’s life.”

Setting Industry Standards in Offshore Well Management
The AX9 stimulation has since been recognized as a model for efficient injector well management in Nigeria’s offshore sector. Lawani Raymond’s technical leadership and dedication to operational excellence demonstrate the value of tailored, data-driven interventions in extending well life and enhancing production.

By integrating advanced diagnostic techniques, customized stimulation recipes, and strict quality control, Raymond and the team showcased how proactive well management delivers sustainable results even in the most challenging offshore environments.

Looking Forward: Knowledge Transfer and Continuous Improvement
Committed to advancing industry practices, Lawani Raymond continues to share insights from the AX9 project with other operators and engineers. His focus remains on refining stimulation techniques, enhancing surveillance methods, and promoting early intervention strategies across the offshore energy community.

“Every successful project is an opportunity to learn and raise the bar,” Raymond concluded. “Our work on AX9 proves that with the right approach, we can overcome technical challenges, safeguard assets, and drive Nigeria’s offshore sector forward.”
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