Ready to plug in: Tools for better understanding of wellbore stability

21 Dec 2020
Dr Chris Leonardi
Dr Chris Leonardi

Understanding the stress in the earth surrounding coal seam gas wells is vital when it comes to making decisions about drilling, completion, stimulation, and production in the gas industry.

This is especially true in locations where the in-situ stress and pressure conditions have been altered by past or adjacent production.

As one component of his Advance Queensland fellowship, Dr Chris Leonardi and his team at UQ-CNG are developing new analytical and computational tools to better predict near-wellbore stress under a range of conditions.

He says this will be a highly useful tool for companies in the decision-making process.

“The development of an analytical model to understand stress in the well is really important to inform future work for gas companies.

“It’s been a challenging year for us with COVID-19, but I am happy to report we have been able to document our research findings in a journal manuscript which is currently under review and hopefully will be published early in the new year.

“Our postdoctoral research fellows, Ruizhi Zhong and Travis Mitchell, have also developed a tool for predicting both underbalanced and overbalanced wellbore failures during drilling in depleted coals.  

“This gives us a much better picture of what is happening to the structure of the surrounding coal underground following the extraction of gas. This work is also being prepared for publication and the integration of the Python script into industry workflows (e.g. Techlog and RokDoc software) is being investigated. Good news with the Python scripts now available for member companies to trial.  

“The whole team is looking forward to advancing this work in the new year, looking more closely at the effect of adjacent sandstone and changes to the strength of coal caused by the activation of dominant cleat networks.”