Fiber Sweeps for Hole Cleaning

Abstract

Cuttings transport in highly deviated wellbores is more challenging and critical than in vertical wells. In inclined wells, the fluid velocity has a reduced vertical component that may not be sufficient to transport all the cuttings to the surface. When cuttings returns do not appear to be sufficient for the drilling rate, hole cleaning sweeps are applied to clean the borehole or reduce cuttings bed thickness. Fiber-containing sweeps have been very effective in cleaning highly deviated and extended reach wells. In addition, substantial torque and drag reduction has been reported when fiber-containing drilling fluids are used in the field. Although field observations are encouraging, currently very little is known about flow behavior, hydraulics and cuttings transport efficiency of fiber sweeps.There is a great need for understanding how fiber particles enhance the cleaning capabilities of fiber-containing sweeps. The interaction between fiber particles and drilling fluid is still not fully understood, although the improvement in cuttings and solids transport is attributed to the formation of a fiber mat/network that enhances the carrying capacity of drilling fluids.This article presents results of experimental investigations conducted to study hole-cleaning performance of a fiber sweep. Flow loop experiments have been carried out to evaluate and compare sweep efficiencies of the fiber sweep (0.47% Xanthan Gum and 0.04% synthetic fiber) and the base fluid (0.47% Xanthan Gum). Equilibrium bed heights were measured at different sweep flow rates in horizontal and inclined configurations. Results from this study indicate that a fiber-containing sweep has better hole cleaning capabilities than the base fluid, even though these two sweep fluids have very similar rheological properties. Moreover, adding fiber slightly reduces friction pressure loss under turbulent flow conditions.

Experimental Study of Hole Cleaning Performance of Underbalanced Drilling at Downhole Conditions

“…The effectiveness of using fiber sweep for hole cleaning and reduction of cutting bed thickness in horizontal and highly deviated sections was recently considered [1,2,10]. Valluri et al [10] investigated the effect of rheology of the sweep fluid on sweep efficiency under LPAT and EPET conditions.…”

“…It was reported that, in the absence of drill pipe rotation, high viscosity and high density sweeps were found to be ineffective in a horizontal configuration and temperature affects the sweep efficiency by changing the rheological properties of drilling fluid. Ahmed and Takach [1] conducted hole cleaning performance of a fiber sweep and discovered that the Xanthum gum mixed with synthetic fiber has better hole cleaning capacity than when mixed with base fluid in horizontal well configuration. Similarly, Cheung et al [2] conducted experiments with drillpipe rotation speeds (0 -90 rpm) and different fiber concentrations.…”

“…Thus, in order to achieve drilling cost reduction, improvement in drilling technologies for the development of vertical, directional and horizontal wells is imperative. Poor hole cleaning which often occurs in the highly deviated sections and horizontal sections of the complex structural wells [1] could be attributed to decrease in cutting carrying capacity of the drilling fluid. Hole cleaning is one of the major factors affecting cost, time and quality of vertical, directional and horizontal well [4].…”

Analysis of Hole Cleaning for a Vertical Well

“…Equilibrium bed heights were measured at different sweep flow rates in horizontal and inclined configurations. [12] described and modeled a simple and more reliable artificial neural network (ANN) for various borehole conditions using some critical parameters associated with foam velocity, foam quality, hole geometry, subsurface condition (pressure and temperature) and pipe rotation. The average absolute percent relative error (AAPE) between the experimental cuttings concentration and ANN model is less than 6%, and using MLR, AAPE is less than 9%.…”