Delineating the Multi-Stacked Domanik Play in the Volga-Urals Basin, Russia

Abstract

This paper shows the importance of an integrated, multidisciplinary approach to exploiting the unconventional Domanik Play in the Volga-Urals Basin in Russia. A combination of understanding the reservoir and applying different completion techniques is necessary to verify the best way to drill, complete, and produce the basin. In 2012, DirectNeft drilled the first well specifically targeting the Domanik interval in the Volga Ural Basin. This discovery well tested oil from multiple horizons within the 350+ m (1150’) thick "Domanikoid" section. In the broad Upper Frasnian interval, Well A was the first successful hydraulic fracture treatment in the Domanik. The subsequent Well B, seven miles to the northwest, penetrated a largely identical Domanik section and was also fractured and tested in multiple horizons, including the Upper Frasnian. Well tests, logs and core analysis have identified two primary and two secondary productive intervals within the Domanik. These two wells provided the first sets of modern logs in the area, which are critical to better understand the reservoirs. In addition, the coring of key intervals and extensive analysis of those cores have proven invaluable in understanding the nature of the reservoirs. Existing well control and seismic data clearly indicate the thick section of Domanik rocks extends throughout the area. The presence and viability of oil saturated Domanik low permeability reservoirs has been confirmed by the two wells. Oil flows have been recovered from perforated intervals of the Tournaisian, Zavolzhian, Famennian and Upper Frasnian. Based on these exploration findings, subsequent operations expanded the project by drilling four horizontal wells in 2017-2018, three of which have been completed. Objectives are multi-fold and included further delineation of the four productive intervals by refining the understanding of geologic, petrophysical and geomechanical models that influence the completion and stimulation operations, ultimately impacting production. Early results from the completed wells have shown a rapid improvement in production results, showing that the multidisciplinary workflow is successful. Future tests incorporate significant increase of entry points to further prove the success of the play. This paper describes the methodology and modifications implemented based on improved understanding of the reservoir, including the use of multi-stage completion techniques. Also discussed are operational issues related to implementing state-of-the-art completion techniques including sliding sleeves, coil-tubing operations, jet cutting operations and plug and perf operations.