Ch6 - Drilling Fluids

Ch. 6 Drilling Fluids

DRILLING FLUIDS

1. Functions and Properties of Drilling Fluids

2. Field Tests on Drilling Fluids

3. Water Based Mud

4. Oil Based Muds

5. Solids Control

6. Programming a Drilling Fluid

Types of Fluid

Air

Composition of WBM

Composition of OBM

FUNCTIONS AND PROPERTIES OF DRLLING FLUIDS

• Remove Cuttings :• Plastic Viscosity/Yield Point• Gel Strength• Density

• Control Formation Pressures

• Density

• Maintain Wellbore Stability

• Density

• Inhibition

FUNCTIONS AND PROPERTIES OF DRLLING FLUIDS

• Cool and Lubricate the Bit :• Fluid Content

• Transport HHP :• Viscosity• Yield Point• Density

FIELD TESTS ON DRILLING FLUIDS

• Density

• Viscosity

• Filtration

• Sand Content

• Liquid and Solid Content

• Ph

• Alkalinity

• Chloride Content

• Activity

• CEC

Mud Balance

Mud Balance

Marsh Funnel

Marsh Funnel

Fann Viscometer

PV and YP

Typical Viscosities

Typical Yield Point

Filtration Device

Solids Content Device

OIL BASED MUDS

• Water in oil Emulsion• Wettability Control• Balanced Control• Viscosity Control• Filtration Control

Structure of Oil Based Mud

SOLIDS CONTROL• Introduction :

– Screening – Settling – Dilution

• Solids Control Equipment :– Vibrating Screens– Hydrocyclones– Decanting Centrifuges– Mud Cleaner

• Systems

Solids Size Distribution

Hydrocyclone (Lightweight Mud)

Hydrocyclone (Heavyweight Mud)

Solids Distribution

Centrifuge

Solids Control System(Lightweight Mud)

Solids Control System (Heavyweight Mud)

DRILLING FLUID MECHANICS

1. Introduction

2. Flow Patterns and Reynolds Number

3. Rheological Models

4. Frictional Pressure Drop in Pipes and Annuli

5. Frictional Pressure Drop Across a Bit

6. Optimising the Hydraulics of a Circulating System

Introduction

• Primary Function of Drilling Fluid

– Remove Cuttings

• Optimum Use of Circulating Fluid

• Optimise ROP

• Circulating Pressure Losses :

– Increasing Flow Rate

– Decreasing Flow Area

– Increasing System Length

– Increasing Density and Viscosity of Mud

Circulation System

Optimising HHP at Bit

Value of HHP

Flow Patterns and Reynolds Number

• Laminar Flow • Turbulent Flow• Transition :

– Newtonian Fluids– Non Newtonian Fluids– Reynolds Number (2100)

FlowPatterns

Rheological Models

• Newtonian

• Non Newtonian :– Bingham Plastic– Power Law

Rheological Models

Newtonian Fluids

Non-Newtonian Fluids

Pseudo-plastic Fluids

Bingham Plastic Fluids

Power Law Fluids

Frictional Pressure Drop in Pipes/Annuli

• Laminar Flow :– Assumptions– General Equation– Newtonian Fluids– Bingham Plastic Fluids– Power Law Fluids

• Turbulent Flow :– Newtonian Fluids– Laminar/Turbulent Transition– Bingham Plastic Fluids– Power Law Fluids

Variables Involved in Calculating Pressure Drop

Model for Frictional Pressure Loss

Turbulent Flow

Friction Factors

Friction Factors

Frictional Pressure Drop Across a Bit

• Nozzle Sizing

Bit Nozzle