The College of Engineering at the University of Baghdad held a public defense session for the master’s thesis presented by the student Mueyed Khalaf Bandar in the Petroleum Engineering Department. The thesis, titled “Safe Mud Weight Window Prediction for Deep Wells in Southern Iraq Fields”, was discussed on Sunday, December 15, 2024, in the Petroleum Engineering Department’s discussion hall, under the supervision of Assist. Prof. Dr. Nagham Jasim Fayadh.
The examination committee consisted of the following esteemed professors:
- Assist. Prof. Dr. Samira Mohammed Hamdallah – University of Baghdad / Petroleum Engineering – Chair
- Assist. Prof. Dr. Kazem Jawad Abdul-Kazem – University of Thi Qar / Petroleum and Gas Engineering – Member
- Lecturer Dr. Qahtan Adnan Abdul-Aziz – University of Baghdad / Petroleum Engineering – Member
- Assist. Prof. Dr. Nagham Jasim Fayadh – University of Baghdad / Petroleum Engineering – Member and Supervisor
Objective of the Research:
The study addresses borehole instability, a common issue encountered during drilling operations, particularly in deep wells with high productivity, such as those in the Halfaya Oilfield. In this research, a geomechanical model was developed using well log data (density log, sonic log, and gamma-ray log) to calculate pore pressure, determine the value and orientation of far-field stresses, and assess rock mechanical properties. The results were calibrated to analyze borehole wall failure using three failure criteria: Mohr-Coulomb, Mogi-Coulomb, and Modified-Lade. Subsequently, the study predicted the safe mud weight window and identified the optimal drilling trajectory for new wells using Techlog and Landmark Compass software.
Key Findings:
The results revealed that formations such as Ahmadi, Nahr Umr, Shuaiba, and Zubair are unstable. The study suggests drilling these formations with mud weights of 12.5-14, 13-14, 13.5-15, and 14-15 respectively, and at an inclination angle of less than 35° towards the minimum horizontal stress direction to avoid borehole instability.
Additionally, the findings showed that the Mogi-Coulomb failure criterion is more accurate than the Mohr-Coulomb and Modified-Lade criteria, as it accounts for intermediate stress. This was confirmed by matching the results with actual failures observed through caliper and drill bit size logs.
After a thorough scientific discussion by the respected committee members, the student successfully defended his thesis and was awarded a Master’s degree in Petroleum Engineering
