BAKER HUGHES - Drilling Fluids Reference Manual

Oil / Synthetic Fluids
Chapter 5
Oil-base fluids, like other drilling fluids, must be properly applied to derive all the benefits
associated with them. There are obvious advantages to using these systems; otherwise they
would have ceased to exist in the industry. Likewise, there are disadvantages which limit oil
fluids. In situations where oil-base fluids can not be used, synthetic fluids utilizing non-toxic,
non-sheening olefin isomers are used. These synthetic-base systems are environmentallysafer
alternatives to traditional oil-base systems.
Introduction
The advantages listed below frequently outweigh the disadvantages; oil- and synthetic-base fluids
continue to be used in difficult drilling environments and in special applications. The fluids are most
commonly prepared as emulsions of brine water in an appropriate oil- or synthetic-base fluid.
In the past, the commonly used oils for drilling fluids were No. 2 diesel, and low-aromatic-content,
low-toxicity mineral oils. Crude oil has been used; however, due to safety, health and environmental
issues, its use is now rare. Baker Hughes Drilling Fluids (BHDF) CARBO-DRILL ® systems use
diesel or mineral oil as the base fluid.
The development of systems that use synthetic fluids as a replacement for diesel and mineral oil have
eliminated many of the environmental, health and safety issues traditionally associated with oil-base
drilling fluids. These synthetic-base fluids have found application in many offshore areas where the
discharge of fluid and cuttings from traditional oil muds are restricted. The SYN-TEQ ® system,
prepared from various environmentally friendly base fluids, is an effective and environmentally
acceptable substitute for the CARBO-DRILL system.
A brief summary of the ADVANTAGES and the DISADVANTAGES of oil-base (non-aqueous)
drilling fluids follows. Unless specifically indicated otherwise, the information contained in this
chapter applies to both oil and synthetic base fluids.
Advantages of Oil-Base Fluids
1. Shale Stability and Inhibition
Properly conditioned oil-base fluid should have a minimal effect on any shale formation. With correct
internal phase salinities, oil fluids provide gauge holes through water sensitive shales combined with
long-term borehole stability. This is a true statement as long as tectonic stresses are not a factor.
2. Temperature Stability
Oil-base fluids have application in wells with high bottom-hole temperatures. Oil-base fluids have
shown stability in wells with logged bottom-hole temperatures in excess of 550°F (288°C).
Baker Hughes Drilling Fluids
Reference Manual
Revised.2006 5-1