Schlumberger - Mud Removal.pdf - Mud Removal Objectives of...

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Mud Removal
Copyright © 2001 2013, Schlumberger. All rights reserved Objectives of Primary Cementation Provide complete isolation of zones (Hydraulic Bond) To support the casing (Shear Bond) Protect casing string 2
Copyright © 2001 2013, Schlumberger. All rights reserved Mud Removal & Cement Isolation The Most and First important aspect of cement job A 3-step process before cementing 1. Hole cleaning + Conditioning the drilling fluid 2. Displace the drilling fluid from the annulus & Replace the mud by cement slurry 3. Cement is setting, properties and Isolation should not be affected by contamination (mud..) Avoid mud channelling 3
Copyright © 2001 2013, Schlumberger. All rights reserved Efficient Cement Placement Check for efficient mud removal to prevent mud channeling and to ensure zonal isolation Optimize casing centralization fluid properties :mud spacer slurry(ies) pumping rate Select Displacement Regime Turbulent Flow Efficient Laminar Flow Select Preflushes & Spacers Ensure Flat interfaces between fluids Avoid static mud Wall cleaning 4
Bulk mud removal
Copyright © 2001 2013, Schlumberger. All rights reserved The Flow of Fluids Shear Stress τ Shear Rate γ = Apparent Viscosity r V 1 F A A A A V 2 1 Poise = 100 centiPoise = 0.2089 lbf.sec/100ft 2 - 1 Pa.s = 2.089 lbf.sec/100ft 2 Oilfield units dv dr v v r   2 1 2 100ft sec f lb rate shear stress shear · 6