West-Siberia, Russia. Drilling in unconventional reservoir

Goal 

• Drilling the first horizontal wells in the Bazhen – Abalak formations 
• Steering the well into the sweet spot  
• Minimizing drilling risks and NPT 

Challenges 

• Inefficient Shale swelling inhibition by the drilling mud. 
• Chemical instability of shales 
• Regular log interpretation methodologies cannot be applied 
• Zones with abnormally high pore pressure 
• Target reservoir is the unconventional Bazhen formation   

Technical solutions 

Introduction of an extended logging set (determined intervals based on nuclear-magnetic logging and intervals with HC content based on dielectric dispersion multifrequency method) for identification of fluid and reservoir properties 

Application of high-resolution core thermal profiling  

Integrated approach of Geosteering, Petrophysics and Geomechanics during drilling in real-time based on LWD data 

Results 

• Successful drilling of the first horizontal wells in the Bazhen - Abalak formations of the oilfield.  
• As a result of avoiding unstable Abalak formations, no NPT due WB instability was detected 
• The company goals on production were reached by maximizing sweet spot coverage thought trajectory correction in real-time. 
• Low permeability formation was studied, and its data used by the company for the future developments  
• The HF ports were located based on extended logs interpretation and for maximizing targeting the areas with high HC saturation.