Transportation of Cuttings in Inclined Wells

Abstract

One of the most important functions performed by drilling fluid is the removal of cutting from the bottom of the hole to the surface. This function must be performed efficiently if not, the cuttings produced during drilling process will accumulate in the annulus. This problem in directional drilling is featured by gravitational forces. Problems resulting from inefficient cutting transport include pipe stuck, wear of bit, reduction in penetration rate, high torque and drag with many other problems encountered. In high angle deviated wells, the cutting goes through a complex path to the surface where some of the cuttings gravitate to the low side of the well. Reduction in any problem associated with improper cutting transport require good understanding in cutting transport mechanisms. This research focuses on calculating the minimum annular velocity of drilling fluid and minimum pump flow rate which is required to achieve hole- cleaning and lifting of the cutting to the surface, taking into consideration the main parameters that affect the coring capacity of the drilling fluid, for this purpose, data of a deviated well (X) located in Kurdistan region of Iraq is collected to determine slip velocity, annular velocity, critical flow rate and carrying capacity index taking in consideration the mud used and the angle of the deviation using the drilling formula spread sheet V1.6.