Formation fluid refers to the naturally occurring liquids and gases contained in geologic formations. Fluids introduced during the drilling process are called drilling fluids. Fluids in an oil or gas reservoir are called reservoir fluids. The fluids flowing from the wellhead of an oil or gas well are called production fluids.
Formation Fluid is the naturally-occurring fluids and gases in the pores of a formation rock. The fluid may be oil, gas and/ or water that are contained in geologic formations. When the formation fluid is used during oil well drilling, it is referred to as drilling fluid. When the fluids are found in an oil or gas reservoir they are referred to as reservoir fluids.
Formation fluid is created by organic material, mostly plankton and algae, proteins and the life floating in the sea. When the organic material is buried with accumulating sediment at the seabed it is transformed into liquid hydrocarbons and gases, i.e. fluids, under sufficiently high temperature and pressure. It takes millions of years in transforming this organic material into fluids. This naturally forming fluid gets trapped in the pores of the rock and is known as formation fluid. This formation fluid forms oil and gas reservoir with various saturation of oil, gas and water.