Some Results of Tectonic Evolution Study of Northern West Siberia Fields

Summary In the north of West Siberian basin, fields have relatively complex fault pattern. Most hydrocarbon pools of the field are tectonic traps. This makes understanding tectonic evolution of the area very important. Methodology used in this study is based on restoration modeling of seismic sections (paleoreconstructions, accounting for geomechanical properties), structural analysis of sections and maps. As a result, a geologically consistent structural and tectonic model was created and interpretation of faults and horizons was improved. Timing of faults activity and anticline formation usually is not taken into account in oil and gas companies working in this region, but it is very important. It should be used in risk estimations and in basin and reservoir modeling, as timing of the fault activity determined in this work helps to explain dry wells in some intervals. Some important conclusions for regional geology can be made. Four stages of tectonic activity were defined: oblique extension with creation of en-echelon normal faults in Middle Jurassic, growth of anticline and creation of normal faults in Early Neocomian, Middle Albian-Cenomanian and Post-Cenomanian. Strike-slip movements with elements of extension and compression explains growth of normal faults in the same time with growth of the anticline.