A new tendency in Tatarstan’s oil industry involves reserves growth due to heavy oil, as well as heavy oil production. Development of heavy-oil reservoirs requires knowledge of oil reservoir geology and water-saturated zones (water lenses) which significantly affect wellstream watercut. Reservoir development is complicated by the fact that these water lenses are isolated fr om each other.
The paper studies the problem of water zones presence in heavy oil reservoirs.
This paper analyzes basic aquifer systems confined to heavy oil accumulations in Sheshminskian horizon and discusses water zones distribution. It also presents well test data, well logging data, and core analyses data to confirm water presence in heavy oil reservoirs. Hydro-chemical analysis has been conducted to define the degree of aquifer impact on heavy-oil reservoirs in Sheshminsky horizon.
Appraisal wells drilled in some anticline structures including Polyanskoye, Mikhailovskoye, Melnichnoye, Chumachkinskoye, and others, demonstrate gas shows depending on caprock (Lingula clays) stability. In those areas wh ere Lingul clays are not so stable, i.e. prone to fracturing, reservoirs contain degassed oil. Voids in the reservoirs with no gas shows are most likely filled with water.
This paper discusses areal extent of heavy-oil reservoirs with gas shows, and presents gas elemental composition.
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