Geomechanics Study: Key to Successful Development of Unconventional Resources

Abstract

With the rising energy demand, operators in Middle East are now focusing on developing Unconventional resources. To optimize hydraulic fracture stimulation, most of these deep gas wells are required to be drilled laterally and in the direction of the minimum horizontal stress. However, this poses an increased risk of stuck pipe due to hole instability and differential sticking, which makes drilling these wells challenging. Over the last couple of years one of the operators in Middle East had 1500 days of lost time due to stuck pipe which translates to around $100 million worth of red money. One of the stuck pipe mitigation strategy is to perform both Pre-Drill and Real Time Geomechanics analysis. This paper presents the results of 1D Mechanical Earth Models case studies across multiple formations and wells which helped the client in reduce NPT, providing a roadmap to optimized drilling of gas wells and understanding the formation risks for wellbore collapse before drilling.

The workflow used for building the 1D-Geomechanical model required for optimizing the drilling plan and optimizing the direction for enhancing gas production is demonstrated in this work. The 1D model integrates petrophysical logs, acoustic data, drilling history, frac data and pore pressure data for identification of the current stress state.

The resulting 1D-Geomechanical model gives a new understanding of the in-situ stresses along with optimized wellbore stability mud weight predictions for effectively reducing the risk of kicks, mud losses and the risk of borehole shear failures. Integrating Petrophysics data, offset well drilling data and pore pressure fracture gradient data helps in calculating the in-situ stress which is calibrated with drilling events giving a clear idea of the associated risks, the best direction to drill wells and identify stress field around the wellbore.

1D Geomechanics model is key to successfully drilling gas wells along minimum horizontal stress direction and along the weak bedding planes. Additionally, having a better understanding of the fracture gradient in the carbonate formations enables optimal reservoir development and production.

This paper will provide a unique workflow that combines well engineering, project management, fracture analysis and geomechanics modeling and cover multiple scenarios including reducing stuck pipe issues in unconventional wells, identifying weak bedding planes, real time monitoring of mud weight to mitigate wellbore stability issues and drilling in unconventional formations.