We have considered producing Stoltenberg field with horizontal wells. The following data are given
- Viscosity , reservoir oil : 5 cP
- Length of the completed interval : 450 m
- Horizontal permeability : 0.226 m2
- Formation factor : 1.05 m3/Sm3
- Well radius: 0.2 m
- Reservoir pressure: 220 bar
- Density , reservoir oil : 766 kg/m3
- Expected skin factor : 4.5
- Productivity index 9.58 10-9 Sm3/s/Pa
We assume inner diameter : 0.15 m, for the liner through the producing interval. a) Estimate the flow speed along the completed interval, if we produce 3000
Sm3 / d and assume constant inflow density. b ) Estimate the pressure drop along the completed interval c) Estimate how much the inflow density may vary due to pressure drop along the completed interval d ) Will the inflow density be significantly affected by the pressure drop along the completed interval

The well considered in task 6.1 may be drilled so that the length of the completed interval is increased to 1500 m. Correspondingly increased total output may then be achieved a) Estimate how much inflow density will vary due to pressure losses along the completed interval b) Design orifice-based control for constant inflow density c) Estimate the effective inflow performance: how the outlet pressure from the liner (= inlet pressure to the tubing) varies with the total production rate d) It is likely that the productivity index is twice as large as assumed above.
Examine how this will affect the inflow density and the effective inflow performance

A well is drilled through two zones with the following properties
Zone 2
Zone 1
Length
300 m
100m
Spec. PI
1 m3/d/bar/m
5 m3/d/bar/m
Reservoir Pressure
230 bar
235 bar
The zones contain similar oil :
Oil density at reservoir conditions: 710 kg/m3
Formation factor : 1.5 m3/Sm3
The well is considered completed with pipe with inner diameter of 150 millimeters. We will assume a friction factor 0.02 for flow in this pipe. a) Estimate the well pressure and production from each zone if the well is completed conventionally, and produces totally 5000 Sm3 / d b ) Estimate the well pressure and production from each zone if the total production decreased to 500 Sm3 / d
Reservoir considerations indicate total production 5000 Sm3 / d, with inflow control to achieve equal inflow flow density in both zones c ) Estimate the pressure at sand face and in wellbore pipe and with such a flow control d ) Suggest design of orifice-based controls units and the locations of these e ) Estimate the well pressure and production from each zone (with ICD ) if the total production decreased to 500 Sm3 / d

The reservoir described in Problem 6.2 produces oil, the following data given :
Zone 2
Length
300 m
Spec. PI
1 m3/d/bar/m
Reservoir Pressure
230 bar
Zone 1 100m 5 m3/d/bar/m 235 bar
Zone 1 is equipped with orifice based inflow control, equal orifice size .
Distance between control units 12 m
Number of orifices in each control unit 3
Orifice diameter 3.8 millimeters
Zone 2 has no inflow control
With total production: 5000 Sm3 / d = 7500m3 / d, the inflow density in Zone 1 and Zone 2 becomes approximately constant : q
L
= 18.75 m3 / d/m
The upper part of the reservoir contains gas
Gas density at reservoir conditions: 200 kg/m3
Viscosity, reservoir gas : 0.015 cP a) How much will flow density increase by gas breakthrough in Zone 1 b ) How much will flow density increase by gas breakthrough in Zone 2