A New Robust Approach for Hole Cleaning to Improve Rate of Penetration

Abstract

Abstract Hole cleaning evaluation and prediction presents a challenge in drilling industry. The optimization of hole cleaning can reduce the down time during drilling operations. Good hole cleaning means high rate of penetration and less drilling problems. In this paper, a robust hole cleaning model is presented. It is based on monitoring and controlling simultaneously the carrying capacity index (CCI) and the cuttings concentration in the annulus (CCA) to ensure perfect hole cleaning. The cost of drilling can increase tremendously if not enough attention is paid to ensure proper hole cleaning. The knowledge of the size of cuttings, size of annulus, flow pattern, and down hole fluid properties cannot be determined with high level of accuracy using hole cleaning indicators such as transport ratio, hole cleaning ratio or transport index. Cutting concentration in annulus (CCA) alone cannot reveal the drilling mud properties, while the application of CCI alone will not help in optimizing ROP to the desired limit. The drilling parameters and mud rheological properties in certain hole sections were collected and analyzed first to determine the effect of mud properties and drilling parameters on hole cleaning and ROP performance. The data selected are from the same hole size, formation type and mud type. The relationship between mud rheological properties and CCI was then evaluated to determine how strong they are. This step helps determine the significance of mud rheological properties on estimating CCI. CCI and CCA were then simultaneously monitored and controlled to ensure proper hole cleaning leading to optimization of the Drilling operations and reduction in the drilling time. The data analysis demonstrated a strong link between rheological parameters and CCI. The approach was then validated by trial testing it in the field. The results showed that efficient hole cleaning level was achieved, which facilitated improvement of rate of penetration. It was used to drill in challenging hole sections and improved the well drilling performance by more than 55%, mitigated stuck pipe incidents, and eliminated wiper trips, reaming trips, and pumping of sweeps. The new approach or hole cleaning model showed the importance of combining CCI and CCA to optimize the drilling operations and reduce the time. This is the first time to combine the two techniques for hole cleaning optimization. The new hole cleaning model will help the drilling engineers drill a clean, stable hole in short time, and hence reduce the total cost of the drilling operations.