The research of Seyyed Shahab Tabatabaee Moradi, an associate professor at Sahand University of Technology (Tabriz, Iran), has been published in the Journal of Mining Institute.
Hole cleaning quality - that is, the removal of rock cuttings and their transport to the surface - is important not only for drilling efficiency but also for the entire subsequent field development. Ultimately, it determines the achievement of projected hydrocarbon production rates and incident-free operations. There are known cases when poor cleaning reduced borehole stability, leading to gas kicks to the surface.
The scientist facilitated the decision-making process for hole cleaning parameters using uncertainty analysis with the Monte Carlo method, developed by American physicists in the 1940s. The scientists named it as an allusion to the casino, though their work was far more serious - they were working on the US atomic project at Los Alamos laboratories.
Seyyed Moradi in his research "A probabilistic study on hole cleaning optimization" describes the application of the Monte Carlo method to the well cleaning process in an actual shale formation. The input data for the probabilistic study, including drilling fluid flow rate, its physical properties, density, and average cuttings diameter, were obtained from drilling experience. The formation had been drilled by several wells with different operational parameters and fluid properties, based on available geological and technical conditions.
As a result of the analysis, the drilling control team obtained a distribution of the model's output data characterizing cleaning quality, with specific probability for each value. For example, it was established that the drilling fluid's transport ratio exceeds the threshold value with 90% reliability. This indicates efficient cuttings transport during the cleaning process.
Having such probabilistic data for all key parameters, more reliable decision can be made for further hole cleaning optimization, which subsequently positively affects the well's profitability.
