Cyclic waterflooding as one of the methods of enhanced oil recovery is a fairly effective technology to maintain the level of oil production in developed fields. In 2010 Udmurtneft JSC started the using of the dual injection equipment. The equipment allows cyclic injection for only one selected production zone. With an integrated approach to the management of cyclic waterflooding, one of the tasks is to assess the actual efficiency of cyclic injection over past periods, for which it is recommended to use daily production data for impacted production wells. To assess the actual effectiveness of cyclic injection based on daily production data, information is required on the dates of its beginning and end.
The author developed an algorithm to recognize cyclic injection mode of water injection well based on daily reports of its rate. The algorithm is based on the moving average for adaptive selection of the main trend in the injection. On the one hand, it allows identifying the cyclic mode for wells, which completely shut in the corresponding half-cycle (zero injection rate). On the other hand, the algorithm can also be used for wells with dual injection equipment, for which cyclic injection is carried out only within one of the production zones, for the other production zone the injection is carried out in normal mode (the variation of injection rate about its mean). The proposed algorithm makes it possible with 90% reliability to recognize cyclic injection intervals in wells with stop of water injection both in all opened production zones and in a part of them.
References
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