Drilling Fluids Introduction
Drilling Fluids Introduction
Drilling Fluids Introduction
Management
INTRODUCTION
DRILLING FLUIDS
Drilling Fluids are the Colloidal systems, containing
solids, liquids and gases as per the requirements,
basically to transport the drill cuttings from the
bottom of the well to the surface, with out damaging
the well bore and well formations.
Drilling Fluids are as important for drilling an oil and
gas well as the blood for the human body. The cost
for maintaining a good drilling fluid may be 5 to 10
percent to that of the cost of the well, but it’s bad
maintenance may cause the damage to thousand
times or even more
Schematic diagram showing circuit of drilling fluid
through a well in rotary drilling.
IMPORTANT GEOLOGICAL CONCEPTS FOR
DRILLING AN OIL/GAS WELL
Sedimentary Rocks :
These rocks are formed by the erosion of any type of
rock by water and wind flow and followed by the
cementations by the over burden pressure of further
sedimentary depositions. These are the most soft rocks to
drill among all the three types of rocks. Oil/Gas is mainly
found in these rocks only.
Metamorphic Rocks :
These rocks are formed by the temperature and
pressure application on Sedimentary rocks. These rocks are
having drilling hardness between sedimentary and Igneous
rocks. Very little oil/gas is found in these rocks.
IMPORTANT SEDIMENTARY ROCKS
• Soft Clays
• Clay Stone
• Shale
• Sand Stone
• Silt Stone
• Lime Stone
• Basement
IMPORTANT PROPERTIES OF ROCKS
• Formations to be drilled
Which formations are likely to be encountered during
drilling of any well, have the direct relation with the
properties of drilling fluids. So the knowledge of different
formations with their specific characteristics, may help in
planning a more suitable drilling fluid to drill them smoothly.
DRILLING FLUID MANAGEMENT
• Pressure & Temperature Conditions
The temperature and pressure profile of the well is
also an important factor to design the drilling fluids as
their stability and working efficiency are temperature
dependent.
• Casing Policy
Suitable casing policy should be decided in order to isolate different
formation based on pressure profile and different type of formation
of producing zones. Provisions of one or two casings may be kept
to cover any un-expected situations / complications in the well.
Parameters of the different casings should be well defined.
DRILLING FLUID MANAGEMENT
• Geo-Technical Order
For every well GTO should be prepared
covering following parameters
• Name, location, type and purpose of the
well to be drilled
• Formations expected to be encountered.
• Temperature and pressure profile
• Zones of interest
• Expected hole problems
Geo-Technical Order