An Accurate Yet Simple Method to Estimate Caving Volume for Real-Time Drilling Operations

Abstract Accurately calculating caving volume during real-time drilling operations has become increasingly critical for efficient drilling. Such precision can mitigate issues like pack-off and stuck pipe problems resulting from improper hole cleaning. This study introduces a novel and thorough methodology for calculating caving volume at every drilling depth in a real-time drilling operation with a layer-by-layer realistic method through wellbore stability calculation. A caving volume calculation model has been developed targeting real-time wellbore stability analysis and utilizing correlations uniquely tailored to each lithology and field. When real-time data is not present, the model could employ predetermined correlations. However, when real-time data becomes available, it is directly incorporated. The choice of failure criteria is based on lithology; for instance, Mogi-Coulomb is applied to carbonates, while Mohr-Coulomb to sandstones and shales. During each depth, wellbore stability analysis is conducted up to three radii away from the wellbore wall and breakout angles are determined. Combined with certain well parameters, these angles are used in the precise caving volume calculation. When implementing the model using well dataset, impacts of both shale and carbonate lithologies on caving volume were examined with case studies. Moreover, findings show that the caving volume in the shales is substantially greater than carbonates, emphasizing the crucial role of lithology and directional orientation on wellbore shear failures. Real-time calculation of the caving volume with actual cases are discussed in the papers. By incorporating lithology-specific considerations and expanding the analysis radius beyond what previous methodologies offered, the developed model presents a novel approach to caving volume calculations. This enhancement offers considerable potential to adjust hydraulics analysis and improve predictions of pack off and stuck pipe occurrences.