Once the field has been appraised, a field
development plan is drawn. Number of wells to be drilled depends of the field
plan. Thus, a proper knowledge of reservoir conditions is important.
Generally radial flow is assumed for
liquids in the reservoir. For gases the flow is generally turbulent. The flow
is restricted by skin effect. Skin effect is the hindrance in the flow caused
by inflow of solids by mud or perforation against liner or casing.
Coning occurs in the vertical plane when
water is pulled up towards the well bore. Cusping occurs in horizontal plane
when water is pulled up towards the well bore.
The tendency for coning and cusping
increases if-
a.
The flowrate in the well
increases.
b.
The distance between stabilized
OWC and the perforation reduces.
c.
The vertical permeability
increases
d.
The density differences the oil
and water reduces.
To reduce the
tendency the well should be produced at low rate and perforation should be far
away from the OWC is possible. Gas reservoir also has gas coning or cusping.
For horizontal well it is very important
consider the vertical permeability also. If vertical permeability is less than
production will be lower than normal well.
Artificial Lift
The objective of any artificial lift system
is to add energy to the produced fluid. The planning of artificial lift has to
be pre planned.
The following types artificial lift are –
1.
Beam Pump
2.
Progressive cavity pump
3.
Electrical submersible pump
4.
Hydraulic submersible pump
5.
Jet pump
6.
Continuous flow gas lift
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