BAKER HUGHES - Drilling Fluids Reference Manual

Baker Hughes Drilling Fluids
Prevent Lost Returns
Lost returns can be prevented when drilling abnormally low pressure gradient formations by using
low-density oil-base fluid with less than 8.0 lb m /gal (0.96 g/cm 3 ) density.
High Density Fluids
Oil based fluids have a higher tolerance to active and inert solids. Because of this inherit characteristic
in combination with surface wetting agents, high density and drill solids tolerant fluids are obtainable
with excellent rheological properties.
Oil-based fluid chemistry
Fundamental Chemical Concepts
Matter is composed of small, indivisible particles called atoms. Atoms contain a small positively
charged core, or nucleus, surrounded by negatively charged electrons. There are over 100 different
types of atoms, and each type represents an element. Examples would be oxygen, hydrogen, carbon,
sodium, chlorine, etc.
Atoms are attached to one another to varying degrees. When the attraction is strong enough, atoms
form aggregates. Aggregates bound together strongly enough to behave as units are called molecules.
Examples are water, sugar, salt, and hydrocarbons (see ).
Figure 5-1
Structures of Primary Hydrocarbon Classes and Isomerized Olefin (Synthetic Base)
Atoms in molecules have electrons in what are called chemical bonds. When atoms in a molecule
have extreme differences in affinity for the electron, we call the bonds ionic. The electrons in ionic
bonds are transferred from one atom to the other. An example would be sodium chloride or common
table salt. In this example, the sodium (represented by the symbol Na) loses an electron and becomes
positively charged (represented by Na + ). A charged atom is called an ion. Positively charged ions are
called cations. The chlorine (represented by the symbol Cl) gains an electron and becomes negatively
Baker Hughes Drilling Fluids
Reference Manual
Revised 2006 5-7