subject: Different Types Of Drilling Fluids/chemicals [print this page] During Horizontal Directional Drilling (HDD), there is the need to maintain control over the hole. Drilling Fluids are essentially a mixture of water, mud, clay and other chemicals that are used to provide lubrication and stability to the bored hole. Besides, there are several other functions of Drilling Fluids such as removal of cuttings and power transmission to bit nozzles. Drill Fluids are circulated continuously down through the drill pipe to drill boreholes into the earth.
Types Of Drilling Fluids
Drilling Fluids can be classified into following categories: Water Based Drilling Fluids, Air Based Drilling Fluids and Oil Based Drilling Fluids. Liquid Drilling Fluids are commonly referred to as drilling mud. The above mentioned Drilling Fluids are further classified into sub-categories. Some of the major types of Drilling Fluids are as follows:
Water Based Drilling Fluids
Water Based Drilling Fluids comprise of four phases namely, water, active colloidal solids, insert solids and chemicals. In these Drilling Fluids, water is the continuous phase. The continuous phase serves three main functions that are:
.Provides viscosity for further modification into rheological properties
.Suspends reactive colloidal solids such as betonite and insert solids
.Acts as solution medium for all chemicals
Water Based Drilling Fluids are subdivided into various categories on the basis of purpose, additives or clay states.
Oil Based Drilling Fluids
In the Oil Based Drilling Fluids, as the names suggests, any suitable liquid forms the continuous phase. Refined Oils and Lease Crude Oil are commonly used in Oil Based Drilling Fluids. The main components in the Oil Based Drilling Fluids are oil, water, asphalt, calcium hydroxide, surfactants, emulsifiers, weighing chemicals and other chemical additives. Oil Based Drilling Fluids are basically used to enhance and stabilize rheological properties and plastering characteristics.
Air Based or Aerated Drilling Fluids
Air Based or Aerated Drilling Fluids comprise of air-liquid mixture, mist, gas and foam. The continuous phase is formed by air. In this type of Drilling Fluid, water is also added with the compressed air to increase viscosity and provide more cooling to the drill. This helps to deliver the excavated substance to the surface.
The aforementioned types of Drilling Fluids must be carefully selected according to the conditions so as to reduce cost. Certain aspects such as viscosity control, fluid loss control and corrosion control must be kept in mind while selecting Drilling Fluids.
