Hole-Cleaning Performance of Gasified Drilling Fluids in Horizontal Well Sections

Abstract

This study aims to investigate the hole-cleaning process during the flow of a drilling fluid consisting of a gas and a liquid phase through a horizontal annulus. Experiments have been conducted using the Middle East Technical University (METU) multiphase flow loop under a wide range of air-and water-flow rates while introducing cuttings into the annulus for different amounts. Data have been collected for steady-state conditions (i.e., liquid, gas, and cuttings injection rates are stabilized). Collected data include flow rates of liquid and gas phases, frictional pressure drop inside the test section, local pressures at different locations in the flow loop, and high-speed digital images for identification of solid, liquid, and gas distribution inside the wellbore. Digital imageprocessing techniques are applied on the recorded images for volumetric phase distribution inside the test section, which are in dynamic condition. The effects of liquid and gas phases are investigated on cuttings-transport behavior under different flow conditions. Observations showed that the major contribution for carrying the cuttings along the wellbore is the liquid phase. However, as the gas-flow rate is increased, the flow area left for the liquid phase dramatically decreases, which leads to an increase in the local velocity of the liquid phase causing the cuttings to be dragged and moved, or a significant erosion on the cuttings bed. Therefore, increase in the flow rate of gas phase causes an improvement in the cuttings transport although the liquid-phase flow rate is kept constant. On the basis of the experimental observations, a mechanistic model that estimates the total cuttings concentration and frictional pressure loss inside the wellbore is introduced for gasified fluids flowing through a horizontal annulus. The model estimations are in good agreement with the measurements obtained from the experiments. By using the model, minimum liquid-and gas-flow rates can be identified for having an acceptable cuttings concentration inside the wellbore as well as a preferably low frictional pressure drop. Thus, the information obtained from this study is applicable to any underbalanced drilling operation conducted with gas/liquid mixtures, for optimization of flow rates for liquid and gas phases to transport the cuttings in the horizontal sections in an effective way with a reasonably low frictional pressure loss.

Numerical Simulation of Effective Hole Cleaning by Using an Innovative Elliptical Drillpipe in Horizontal Wellbore

“…As seen in Figure 5a, the annular cutting concentration decreases with the increase of rotational speed, due to the centrifugal force and shear force produced by rotating the drillpipe. This is the same as laboratory results of Ozbayoglu et al, 2012 [30]. At the rotational speeds of 50, 100, and 150 rpm, the cuttings' concentration in the annulus, composed of an elliptical drillpipe, had reduced by 7.7, 11.4, and 14.2% on average when compared with the circular drillpipe.…”

Optimization of Flow Rate and Pipe Rotation Speed Considering Effective Cuttings Transport Using Data-Driven Models

“…Ozbayoglu et al [7] developed a new cuttings-transport mechanistic model that includes the effects of drill-pipe rotation and eccentricity. The model can estimate the volumetric distribution phases in three-phase flow and the pressure losses in the horizontal sections.…”

Automated Image Analysis and Contiguity Estimation for Liquid Phase Sintered Tungsten Heavy Alloys

“…In one study, an adaptive window indicator is adapted for choosing an appropriate threshold level for the segmentation of porous materials [26]. The authors worked on extracting physical characteristic features in multiphase flow using segmentation and image processing techniques [27][28][29][30][31][32]. In a similar study , physical characteristics like size, circularity and compactness are extracted for different pressure, temperature conditions of multiphase environments with image analysis techniques [33] in order to estimate foam stability properties.…”