Core Analysis Helps Model Bazhenov Formation Deposits

By Elena Zhuk, April 18, 2014

Lithology, the nature of secondary transformation of reservoir rock, tectonic and structural factors are just some of the factors that influence the quality of forecasting of the properties of Bazhenov deposits in the space between wells.

The core samples can help determine the border between Bazhenov and Abalak formations. “Through targeted research of organic matter we identified the value of 4 percent organic carbon content. The Abalak formation begins where organic carbon content is below this value,” says Nemova. Core composition also has much to tell. Transition to Abalak formation is often indicated by glauconite mineral and much higher clay content.

Recognition of inflow intervals, which are often associated with fractures, is particularly challenging when assessing the Bazhenov formation. According to VNIGNI experts, in this case parameters of the pore-filled storage volume provide extra data on top of fracture values. “The fracture zones, especially large ones, are not always associated with high, or, for that matter, any inflows,” says Nemova.

The presentation cited examples of seismic and geological structure modeling of natural Bazhenov reservoirs, various types of seismic forecast. However, examples of the structure and properties of the Bazhenov formation have been taken from different fields, so results may differ and even contradict one another because of the high lithologic heterogeneity. Therefore, it would be methodologically incorrect to use the results outlined in the examples for interpretation of seismic data on other fields. High volatility and low level of knowledge about the Bazhenov formation deposits force producers to run tailored core research at each field, to set up individual evaluation program and select interpretation methods for seismic and logging data according to the type of fracture and the information available.

Speaker’s Bio

Varvara Nemova heads the research group for shale formations productivity at the All-Russian Research Geological Oil Institute (VNIGNI). She graduated from the Moscow State University and holds a Ph.D. in Geology and Mineralogy. 

She is the author/co-author of a number of scientific articles and she has participated in many international scientific and practical conferences on unconventional oil resources. Nemova co-authored production reports on generation and monitoring models of natural reservoirs in West Siberia on the basis of detailed core analysis and seismic data interpretation. 

Nemova manages projects that comprehensively study Bazhenov suite resources including reservoir models generation based on seismic exploration data, using results of complex lithological, petrophysical and geochemical core studies. 

She conducts experimental work on optimization of complex laboratory core studies of the Bazhenov suite for the purpose of increasing reliability and information value of the results.