RMERC Rock Mechanics seminar Oct 2

Our  Graduate Gathering on  Friday, Oct 2 2015 at 3:30 pm, will be in  in the RMERC Conference Room.

 Our Speaker this week is   Mortadha Alsaba         Mortadha Alsaba   

 He is preparing for his final defense next week!    Please come to listen and offer support and constructive comments.

TITLE:                    INVESTIGATION OF LOST CIRCULATION MATERIALS IMPACT ON FRACTURE GRADIENT

ADVISOR:            Dr. Runar Nygaard

ABSTRACT: Lost circulation is a challenging problem to be prevented or mitigated during drilling. Lost circulation treatments are widely applied to mitigate losses using a corrective approach or to prevent losses using preventive approaches, also known as “wellbore strengthening”. The disagreement among the different wellbore strengthening theories and the lack of understanding the strengthening mechanism resulted in the absence of a standardized method to evaluate the effectiveness of LCM for wellbore strengthening application. An extensive experimental investigation was conducted using a new design high pressure LCM tester to investigate the effects of different parameters on the sealing efficiency of LCM treatments. In addition, hydraulic fracturing experiments, which simulates downhole conditions, were carried out to evaluate the impact of LCM addition on enhancing both; breakdown and re-opening pressure. The results showed that the sealing efficiency is highly dependent on the fracture width and the particle size distribution (PSD) of LCM treatments. A PSD selection criterion for LCM treatments was developed based on a statistical analysis of the experimental results. The addition of different LCM blends enhanced the breakdown and re-opening pressure up to 18% and 210%, respectively. The measured fracture widths under microscope were in the range of the D10 and D25 values of the used LCMs, which suggests the importance of PSD for wellbore strengthening application. Only one analytical model estimated realistic fracture widths when compared to the actual fractures, measured under the microscope.