Drilling Fluid.ppt

Types of Drilling Fluids
➢ Air ➢ Water ➢ Water based mud ➢ Oil based mud ➢ Synthetic based mud
Types of Drilling Fluids
➢ Air Drills faster than any other drilling fluid Can only be used in harder rock with
Functions of drilling fluid
➢ Number two is to prevent blowouts ➢ Blowouts can be catastrophic with
loss of life, equipment and environmental damage ➢ The most common additive for density is barite
1470 1819 1680
BaSO4 FeO.Fe2Co2 TiO2Fe2O
Functions of drilling fluid
➢ Hematite and Ilmenite are not used very often in drilling fluids
➢ Only for very high density drilling fluids ➢ Bottomhole cleaning is primarily performed
Functions of drilling fluids
➢ Remove cuttings from the hole ➢ Clean bottom of the hole (below bit) ➢ Prevent flow of formation fluids ➢ Control torque (reduce friction) ➢ Retard corrosion ➢ Deposit a thin filter cake
Functions of drilling fluid
➢ H2S and CO2 are acid gases - When mixed with water based mud, they lower the pH and promote corrosion - H2S is deadly in small quantities and should be treated immediately - H2S can cause hydrogen embrittlement in high strength carbon steel - CO2 can cause severe viscosity problems
Types of Drilling Fluids
➢ Most salt muds are sodium chloride, potassium, potassium chloride or calcium chloride
➢ Bentonite will not yield or hydrate very well in salt water
you can not drill
Functions of drilling fluids
➢ Symptoms of poor hole cleaning -Excessive torque and drag -Tight hole and bridges on trips -Fill on bottom
Functions of drilling fluid
➢ Formations that will be cased, cemented, perforated and fracture stimulated may not present a problem with formation damage
Types of Drilling Fluids
➢ Water based muds can be broken down into fresh water or brine systems
➢ Fresh water muds are by far the most common drilling fluids in the world
lower production rates No control of formation pressure
Types of Drilling Fluids
➢ Water Water drills better than drilling fluids
with solids Low density, no solids, low viscosity Not all formations can be drilled with
➢ If bentonite is used, it is premixed in fresh water to a high viscosity and then blended into the salt water system
Types of Drilling Fluids
➢ Oil based muds can be formulated to weigh as little as 7.5 ppg with mostly oil
water
Types of Drilling Fluids
➢ Water based muds Clay for viscosity Barite for density Chemicals and polymers to get
desired properties Drill solids as a contaminant
➢ It does become critical in extended reach directional wells and horizontal wells
➢ A good bentonite content and low drill solids content will yield lower friction coefficients
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Functions of drilling fluid
➢ Retard corrosion - Corrosion is reduced by maintaining a pH above 8.5-9.0 - A common additive to increase the pH is caustic (NaOH) - Potassium hydroxide can also be used (KOH) - Corrosion inhibitors or oxygen scavengers can be used to improve corrosion resistance
Drilling Fluid
The drilling fluid is a large and important part of drilling operation
Historical perspective
➢ 1901-The Sprindletop well introduced rotary drilling methods and drilling fluid
Functions of drilling fluids
➢ Drilling fluids cannot do everything
➢ Must decide on priorities ➢ Number one function is to
clean hole ➢ If you do not clean the hole,
Functions of drilling fluids
➢ Transmit MWD information ➢ Prevent change in hole size ➢ Aid in cement placement ➢ Prevent lost circulation ➢ Minimize formation damage ➢ Assist in formation evaluation
➢ Oil based muds are used to drill - Highly reactive shale formations - Extended reach drilling for low friction coefficient - Deep, high pressure, high temperature H2S wells
➢ They can be anything from water and drill solids to complex muds
Types of Drilling Fluids
➢ Salt water muds are specialty muds used to obtain a specifc objective
by the hydraulics and not the mud ➢ Mud additives generally reduce
bottomhole cleaning
Functions of drilling fluid
➢ In most instances, hole lubrication is not a requirement
➢ All drilling fluids are damaging to some extent, if not, it is called lost circulation
➢ The question is whether the damage can be reversed or limited to near the well bore
➢ Oil and synthetic muds will usually yield the lowest friction coefficients but not always