Seismogeological criteria for gas deposits forecasting in the north of Western Siberia

Abstract

Seismogeological criteria for forecasting the gas content of the Aptian-Cenomanian sediments of Western Siberia are identified and substantiated in the study based on a comprehensive interpretation of seismic data, well log data, test results and petrophysical studies results. As a reference object we use the Jubilee oil and gas condensate field, which is located in the Nadym-Pur interfluve. The field contain the unique gas deposit in the Cenomanian reservoir horizon PK1, the Albian sand layer PK18 is productive too. Based on the results of the research, seismogeological criteria for the gas-bearing forecast are formulated. If there is a giant gas deposit in Cenomanian reservoir: 1) there is a reflectors formed on gas-water contacts (GWC) in seismic cross sections, amplitude characteristics of the reflector G, which is confined to the top of the Cenomanian complex, decrease; 2) time thickness (ΔT) increases, the interval velocities (Vint) decrease and amplitude-energy characteristics of the seismic record in the Aptian-Cenomanian complex decrease. The Aptian-Albian sheet gas reservoirs are displayed in seismic cross sections a jump in amplitudes of the seismic record, forming the “bright spot” anomalies in the time sections.