The cutting properties effects on the hole cleaning index (HCI) and annular pressure drop in the worst inclinations after releasing wait on bit (WOB) in an experimental flow loop

Due to importance of hole cleaning on reducing the operational time and cost, especially on directional drilling, it’s decided to attend this subject for a series of activities where the WOB must be released. In this research it’s preferred to focus on the effect of cutting properties such as size, shape, lithology and the concentration of them as an indicator for the latest rate of penetration (ROP). In these situations, the cutting generation is stopped but the mud also contains them from the previous operation. The critical inclination for cutting transport is detected with water. The pressure drop in each test is recorded. The results illustrated that for the meshes between 10-20, there is a saddle point for cutting size in the hole cleaning. With decreasing the size of the cuttings, the hole cleaning index (HCI), Bed length and end point of the bed are increased smoothly from mesh 20 to 30 and then rapidly increased for the other meshes after 30. The bigger specific gravities with little sizes can have the better HCI rather than the lowest SG but bigger sizes. The SG is not a good parameter for predicting HCI. For near densities, the effects of size and shape are more important than lithology. ( Micronized sand and lime). The cuttings with near distance in mesh number such as mesh 10-12, bigger sphericity index (SI), have a little worse HCI rather than larger distances such as mesh 12-20. The combination of different meshes, Lower SI, may have the better result than each of them for example mesh 10-30 rather than mesh 10-12 and mesh 12-20. Mesh size 10-30 has the biggest pressure drop and the mesh size of 12-20 has the lowest one. At the first periods of the time the mesh size of 10-12 has the bigger pressure drop than mesh size of 20-30 but by passing the time, its pressure drop decreased. By increasing the amount of cuttings the pressure drop decreased. By decreasing the density of the cuttings, in the first periods of the time, the pressure drop increased (for sand and silica).