Critical Conditions for Effective Sand-Sized Solids Transport in Horizontal and High-Angle Wells

Abstract

fax 01-972-952-9435. AbstractEffective removal of small sand-sized solids is critical for successful drilling and completion operations in sand reservoirs. Recent experience in extended reach drilling also indicates that inefficient transport of smaller cuttings is a main factor for excessive drag and torque. This study was undertaken to determine two critical conditions for efficient transport of small solids. The two conditions are represented by the Critical Re-Suspension Velocity (CRV), the minimum fluid velocity necessary to initiate solids bed erosion, and the Critical Deposition Velocity (CDV), the minimum fluid velocity required to prevent bed formation.Experiments were conducted in a field-scale flow loop (8×4.5 in., 100-ft long) to determine CRV and CDV, for 0.45 mm and 1.4 mm sands in different fluids over a range of bed heights and hole inclinations. The results show that, depending on sand size and fluid properties, CDV is approximately two to three times larger than CRV. Water is more effective than low concentration polymer solutions for bed erosion. However, polymer solutions are more helpful than water in preventing bed formation. This indicates the need for different drilling fluids for cleanout and drilling operations.A mechanistic model was developed to predict CRV for a solids bed. Both experimental and theoretical results indicate the importance of inter-particle forces that are incorporated into the model. The model accounts for drill pipe eccentricity in any direction in an annulus, which is consistent with experimental observations. The model predictions are in good agreement with experimental results. Existing CDV correlations developed for larger cuttings were verified by experimental data for sands. The differences are around 25%. Results in this study will be useful not only in drilling and completion through sand reservoirs, but also in extended reach drilling and sand control.

Improving the Cuttings Transport Performance of Water-based Mud Through the Use of Polypropylene Beads

“…This outstanding performance has shown that if polypropylene beads were to be commingled with drilling fluid in any drilling operations, it would enhance the cuttings transport and invariably improve the effectiveness of the wellbore cleaning by the transporting fluid. The improvement recorded by the drilling mud with polypropylene beads has been influenced by two major forces that act on slipping cuttings of imperfect sphere in a turbulent flow, namely the gravitational and drag forces (Clark & Bickham 1994;Duan et al 2007;Skalle 2011).…”

Review of Hole Cleaning in Complex Structural Wells

“…Therefore, mud rheology [20][21][22][23][24], particle size [20,21,23,25,26], and drillpipe rotation [6,24,27] continued to be studied.…”

“…In addition, Duan et al [26] still conducted experiments to determine the critical resuspension velocity (CRV) and the Saasen et al [12] Drillpipe rotation Pipe rotation leads to more efficient cuttings transport for gel structure cuttings bed.…”

“…Duan et al [26] developed a mechanistic to predict CRV for a solid bed. The model accounts for drillpipe eccentricity in any direction in an annulus, and is consistent with experimental observations.…”

Cuttings Transport Behavior and Simulation Analysis Affected by Hole Cleaning Tool

“…Therefore, it is very important for horizontal and ERW wells to enhance cuttings transport efficiency. Many researchers have developed a series of helical hole cleaning tools to improve hole cleaning condition and obtained good results [4][5][6]. These tools have helical blades on their surface, and outer diameters of these blades are close to drill pipe sub.…”