First Unconventional Najmah Horizontal Well in Green Jurassic Gas Field Unlocked the Reservoir Potential and Setup Development Strategy Roadmap
Authors: Abdel-Basset M. , Al-Otaibi Y. , Al-Ajmi S. , Al-Mulla S. , Bloushi T. , Al-Mutawa M. , Al-Ajmi M. , Hadi A. 
Published: October 2023

The journey of appraising unconventional reservoirs of North Kuwait Jurassic Gas (NKJG) fields achieved a significant milestone through the successful test in the first horizontal well completed in Najma Limestone (NJ-LS) reservoir in Bahra field. This accomplishment becomes even more remarkable given that none of the previous vertical wells’ tests were successful. This paper will demonstrate the challenges faced in the well placement, completion and stimulation, as well as the implementation of new technologies to achieve Kuwait’s highest ever initial gas production rate. This outstanding success in appraisal well has unlocked the potential of the NJ-LS reservoir and prompted a step-change in its development strategy.

NJ-LS is a tight gas-condensate reservoir with typical porosity ranging from 2 to 9% and very low matrix permeability (~0.01mD) with primary production through natural fractures. To increase the chances of success in encountering fracture corridors, long drain-hole horizontal wells were deemed necessary.

To overcome well planning and placement challenges, detailed seismic attribute mapping and integration of available core and log data were undertaken to place the well in the best sweet spot. Extensive screening of seismic data helped avoid possible seismically mappable hazards and optimize the trajectory to encounter areas with high fracture corridor.

The well was drilled as 6in lateral length of approximately 2900ft and successfully landed as planned. State-of-the-art drilling and real-time geosteering technologies aided in precisely placing the wellbore in the target zone of NJ-LS.

The integrated completion design included eight stages of Multi-Stage Completion, as first-time achievement in NKJG fields. The targeting of shorter stages aimed to accommodate better the reservoir heterogeneity (matrix, fractures, losses, etc) to improve acid stimulation efficiency. Many operational challenges were faced and overcame by multidisciplinary team during the multi-stage stimulation and flow back (e.g high surface pressure ~12,000 psia and presence of H2S).

All eight stages were individually stimulated with high-rate matrix acidizing. Commingle activation, flow back and testing activities were executed in continuous back-to-back operations to fast track well delivery to production. Double degradable balls were used for the first time to open the corresponding FracPORT seat and isolate lower open stages. Two green burners used for the first time in Kuwait, accommodated the high returns during flow back and initial testing.

Continued advancements throughout the full well cycle, from well placement to stimulation, culminated in achieving Kuwait’s highest ever gas production rate on the initial test, with low Water-cut at different choke sizes and high Wellhead pressure (+/- 6500 psia)

Such outstanding results have encouraged the NKJG asset to fast track the extension of this success to other sweet spots as step-change in unconventional reservoirs, supporting the roadmap towards achieving and sustaining the asset’s production target.