Aberdeen, UK

Technical Talk:  Vassilios Kelessidis (SPE Distinguished Lecturer) 

Aberdeen Formation Evaluation Society

Technical talk:  Vassilios Kelessidis (SPE Distinguished Lecturer)  ‘Drilling Optimization Revisited: How Close Are we to Drilling Optimization While Drilling (DOWD)’

Link to youtube recording: contact AFES

Link to slides: contact AFES

Drilling engineers and companies strive towards drilling optimization since the era of drilling, with
continuous improvements over the years. Drilling engineers generate big data during drilling campaigns
but significant information is hidden.
Big Data Analytics and the much-improved Artificial Intelligence and Machine Learning techniques provide
excellent opportunities for enhancements of drilling optimization. Now data could be exploited very
intelligently and ‘on the fly’. However, all this must be done cautiously and always in combination with
appropriately developed physical models to maximize benefits.
For drilling optimization, physical modeling is needed using data to calibrate and tune the models rather
than using only data driven models without physics.
We focus on rock-bit interaction as the most significant area for drilling optimization. Physical modeling
exploits monitored data and generates responses of the bit. The drilling simulator is tuned to match actual
drilling data. Sonic while drilling data provide estimates of rock strength on the fly. An optimization scheme
can estimate drilling parameters on the fly for drilling the next segment and communicates them to the
driller, giving him the capability to ‘ride’ the bit and guide it safely to target.
Take away Idea: Big data analytics and right modelling can help put the driller on the bit.

Vassilios C. Kelessidis is currently a consultant of drilling and petroleum engineering. He has worked in
Schlumberger for more than 9 years and has served later the academia for 18 years: His last position was
Professor & Department Chair at Khalifa University (UAE) (January 2017-December 2018), and Adjunct
Professor at Texas A&M at Qatar (TAMUQ). Previously he was at TAMUQ (2012-2016) and at Technical
University of Crete, Greece (2000-2016).
He works on drilling engineering, drilling optimization, rock-bit interaction, evolving the drilling predictive
simulator, and on cuttings transport, multiphase flows, drilling hydraulics, drilling fluid development and
He has published more than 115 journal and conference papers with 1640+ citations. He is co-author in
SPE Fundamentals of Drilling Engineering, Ch5 – Drilling Hydraulics. He is Associate Editor in SPE Drilling &
Completion since 2016.
He has PhD (University of Houston, 1985), M.Sc. (Oregon State University, 1982) and Diploma (Aristotle
University of Thessaloniki, Greece, 1980), all in Chemical Engineering.

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