The giant Handil field comprises of more than 500 hydrocarbon accumulations, in structurally stacked and compartmentalized fluvio-deltaic sands.

Most of the accumulations consist of a large column of saturated oil underlying a gas-cap, trapped in reservoirs with good rock properties, and have been produced by water injection or strong natural water drive.

In 1995 five reservoirs, representing nearly 1/5 of the field's total OOIP and which had reached their final stage of waterflood development - 58% of the total oil in place had already been produced - were submitted to a further development with lean gas injection to increase the ultimate oil recovery.

To date, after 3 years of gas injection, the recovery factor for these 5 reservoirs has increased by 1.2% of the oil initially in place and the project is considered both a technical and an economical success.

The predominant drive mechanism with lean gas injection have been confirmed by field data. The previous decline of oil productionhas been stopped and the oil rate is now stabilizing. The main monitoring challenge has been the control of gas cycling for most of the producers, particularly during periods of higher injection rates to compensate low injection periods imposed by gas availability.

The very close monitoring of the wells and reservoirs performance, the numerical simulation and material balance studies, have helped to better understand the mechanisms involved and have to led a revised and more efficient policy to maximize oil production.

The experience gained and the analysis of this 3-year old project gives the confidence to pursue the extension of the lean gas injection development to others reservoirs of Handil field.

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