# A Novel Efficient Borehole Cleaning Model for Optimizing Drilling Performance in Real Time
## 2 The Influence of Factors on Borehole Cleaning
### The Main Models to Evaluate the borehole Cleaning Efficiency  
The efficiency of the borehole cleaning evaluation instruments and procedures is diminished if the findings are not received promptly. Addressing any borehole cleaning difficulties as soon as possible is essential to avoid a buildup of cuttings and the possibility of situations in which pipes have been trapped. The drilling crew is able to promptly  
Figure 2: Parameters and their effect on borehole cleaning. evaluate borehole cleaning using real-time models and take corrective action, including modifying drilling fluid properties, adjusting surface parameters, or performing dedicated circulations to move cuttings to the surface. However, conventional rig sensors may not be capable of running some models on real time. Under such circumstances, incorporating sophisticated sensors and models may be necessary [10; 17]. Hence, cuttings transport models based on experimental, mechanical, or field-applied approaches have been developed. As an example, the cutting carrying index (CCI) is an indicator that provides knowledge of the size of cuttings, size of the annulus, flow pattern, and downhole fluid properties that cannot be determined with a high degree of accuracy. [PERSON] developed a simple empirical index to help predict borehole cleaning [13]. When the cuttings are effectively lifted to the surface, the product of the three key variables that have a significant impact on the transport ratio is approximately 400,000. The presence of sharp-edged and well-defined cuttings is a reliable indication of good borehole cleaning [13]. If the edges are rounded, tumbling occurs in the annulus, which means that cuttings are not transported to the surface quickly. A borehole cleaning index or ratio of 1 or greater is considered indicative of good borehole cleaning conditions. When the CCI value is 0.5 or less, the cuttings are more rounded and smaller due to inefficient borehole cleaning, which leads to a longer residence time in the annulus. This CCI is applicable for vertical borehole sections with inclinations ranging from 0 to 25 degrees [13]. For deviated and horizontal borehole sections, CCI must be modified. Another model that allows us to indicate the amount of cuttings beds removed by determining their critical height is called the borehole cleaning ratio (HCR) [27]. An HCR value greater than 1 indicates that the drilling fluid is removing cuttings effectively and maintaining a clean wellbore. On the other hand, an HCR value of less than 1 indicates that the cuttings are settling in the wellbore and not being effectively removed [27]. More importantly, every model performs by considering the influence of different parameters on the obtained results. Table 1 shows various models to indicate the cutting transport or borehole cleaning conditions. As seen from Table 1, each model has specific set of variables that are crucial in assessing different aspects of drilling operations. For instance, the HCR is commonly used to evaluate the risk of a pipe becoming stuck during drilling operations by calculating the ratio between the free height of the drilling fluid in the annulus and the critical height of the cuttings bed [27]. Similarly, the CCI is based on other variables such as mud weight, consistency factor, and annular velocity, and is used to evaluate the ability of the drilling fluid to transport cuttings out of the wellbore. The TR model, on the other hand, is used to assess the efficiency of cuttings removal based on annular velocity and slip velocity [13]. Additionally, the \(\beta^{1}\) model is utilized to evaluate the borehole cleaning attributes for the optimal cuttings lifting ability and cuttings lifting coefficient based on the drilling fluid flow rate, annular area, and cutting diameter [17]. However, among these models, the TI model stands out due to its incorporation of various variables such as mud weight, rheology factor,  
Figure 3: Influence of rotation on cuttings bed; (**a**) low RPM; (**b**) medium RPM; (**c**) at 120 RPM.