The article discusses issues related to various welltesting methods at a field in Western Siberia. Low reservoir permeability, drilling and operating horizontal wells with multi-stage hydraulic fracturing lead to a manyfold increase in the duration of well shutdowns for welltests by recording a pressure build-up curve. Thus, the main well stock cannot be covered only by welltests by recording a pressure build-up curve due to significant losses in production. At the same time, welltests conducted only on wells with a relatively low oil production rate are also less informative. Welltests with the decline analysis do not require well shutdown for evaluating the reservoir parameters. The active installation of pressure sensors at the pump suction of production wells enables carrying out the decline analysis in almost any well. Thus, an increase in the number of these welltests allows to significantly expand the research of the field. In addition, the results of the decline analysis can be used to identify the causes of production changes associated with a formation pressure decrease on the external reservoir boundary, an increase in water cut and a decrease in the productivity index. The authors show how the results of decline analysis can be used for areal analysis and localization of zones with the maximum changes in production. The causes of reservoir pressure decrease in recovery zones of the production well are discussed.
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