Following the successful completion of the pump enhancement programme, all eleven wells have been brought online with flowing bottom hole pressures optimized to reflect the transitional nature of the reservoir behaviour.
A small reduction in pump efficiency was observed in some wells, which after thorough investigation has been attributed to gas ingress through the pumps, in several instances resulting in a pump tripping on account of gas lock. These gas-related effects, together with a gradual decline in water production rates corresponding to lowered average flowing bottom hole pressures, are highly encouraging manifestations of pressure depletion in the reservoir, and characteristic of a reservoir in transition.
While these effects temporarily limit the growth in total gas rates (due to the lessening component of gas carried with recovered water), the rate of gas desorbing from the coals (which flows up the annulus of the wells and is measured separately) has continued to increase on a weekly basis. The desorbing gas rate has increased by over 100% since all wells were brought online with optimized flowing bottom hole pressure. As foreshadowed in the previous reports, the achievement of critical desorption pressure in the central pilot area has, pleasingly, been confirmed by a consequential doubling of desorbed gas from the central lateral well (G14L).
Moreover, the gas/water ratio in the other lateral wells is continuing to increase, which is again indicative of an increasing contribution of gas desorbing from the coals. Based on observed rates of pressure depletion in nearby observational wells, the outer lateral wells are expected to reach critical desorption around the end of September, and to significantly expand the 'pressure sink' area contributing to the production of desorbed gas, leading to a substantial increase in total gas rate. Plans are well advanced for a measured expansion of the Pilot footprint following confirmation of the anticipated short-term performance.
Water handling projects
Efficient (and potentially value-adding) water handling remains critical to the operation of the Pilot. Since the last report, a mobile irrigation scheme has been successfully commissioned to supplement the two existing pivot irrigation areas. These three irrigation areas, together with the on-site reverse osmosis plant, are well positioned to handle the current water production of 18,000 barrels per day (and more). Cropping operations are on schedule, with a third cut of sorghum on pivot 1, and a first cut of oats on pivot 2 due in the coming weeks.
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