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2.
According to the type of well to choose the drilling fluid
system
Area exploration well and forecast well
Choose the well fluid system which doesn t influence the
geological logging and is beneficial to find the production
layer. It means the fluorometric degree and density of the
well fluid should be low and avoid mixing oil.. Try to use
the non-dispersed polymer to maintain a low density and
solid phase.
Producing well
The requirement for drilling fluid is to protect the
hydrocarbon reservoir and improve the drilling speed. The
non-dispersed polymer is normally used in upper part, the
completion fluid is used to oil layer to protect it when
drilling processing reaching the target formation.
Adjustment well
The character of adjustment well is the high formation
pressure. The density of drilling fluid is higher than 2.0
generally and even to 2.7. Usually choose the dispersed
drilling fluid system, oil base drilling fluid if necessary.
Ultradeep well
Requirement for drilling fluid: heat resistance is good;
the high temperature has few impacts on nature; under high
pressure difference, mud cake has good coercibility. Use the
treating chemical and drilling fluid with good heat
resistance. Besides the oil based drilling fluid, dispersed
triple sulphur drilling fluid system is the best water based
drilling fluid to be used for ultradeep well. In recent
years, it has developed into polymer sulphur well fluid
system.
Direction well and horizontal well
High friction of drill string, easily drill pipe sticking,
the unsteady drill wall is heavier than vertical well. Take
more effective measure to caving protection, sticking
protection and cutting carring. Use of cationic polymer
drilling fluid and potassium lime deflocculate drilling
fluid.
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