Several parameters were considered in selecting the optimal artificial
lift application for X field, an initial elimination process was carried out
based on six main parameters. These parameters are namely;
a) Wellbore Accessibility for rig less
b) Field Development Plan for water/gas injection
c) Average Run-life of the artificial lift.
d) Well Depth – deep wells (10,000 – 12,000 ft).
e) Well Trajectory.
f) Existing/ Simplicity of Surface Facilities.a) Wellbore Accessibility
for Rigless Interventions: It will be mandatory that the artificial lift well completion must
have accessibility for gather reservoir data via slickline or coil tubing. With
the accessibility, reservoir monitoring program (RMP) activities listed below
can be carried out easily; 1. Reservoir Pressure Monitoring: static pressure & flowing gradient
survey2. Production Monitoring: production logging, fluid breakthrough
monitoring b) Field Development Plan
(WAG):X field development
plan is comprised of several pressure maintenance methods and recovery systems
such as peripheral water injection, Miscible Water-Alternating-Gas Injection
(MWAG) and CO2 injection. These systems will affect the type of
artificial lift application that will be deployed since the gas production is
expected to increase with time due to potential gas break through. c) Average Run-life:In order to maintain
and extend X field production plateau over a long period of time at reduced
cost, the run life of the artificial lift method to be deployed will be very
crucial in the elimination process.d) Well Depth:Considering that the
depth of X field reservoirs (Zone-I, Zone-II & Zone-III) being evaluated
could reach up to 10,000 to 12,000 FT deep, the artificial lift application
should not be limited by well depth.e) Well Trajectory: The type of wellbore
trajectory can be a constraint on some artificial lift applications. Most of
the wells in X field are deviated and horizontal.f) Simplicity of Surface
The artificial lift
applications that will utilize the already existing infrastructures (such as
gas source & electric power) in X field are going to be given priority. The
simplicity of any additional or surface facility modification to apply
Artificial Lift method is important.Based on the six main important parameters in
the table-5 above, the Artificial Lift screening for X field will focus on
three applications namely Gas Lift, Auto Gas Lift and Electric Submersible
Pumps (ESP) due to it can handling high rate for
deep producers. However,
Auto Gas Lift will include in the Capstone design project II. Gas Lift: This is a method of artificial lift
whereby relatively high-pressure gas (from surface) is injected into a fluid
column to reduce the density of the fluid from the point of gas injection
(through a gas lift valve in the well) to the surface. The injected gas
supplements the formation gas and lightens the flowing pressure traverse (fluid
gradient) above the point of injection, lowering the flowing bottom hole
pressure (FBHP) to create a “drawdown “at the producing formation. This allows
the lower reservoir pressure to lift the fluids to the surface.
Electric Submersible Pumps (ESP): This application introduces energy
(pressure or head) to the well system by accelerating the produced fluids in
centrifugal electrical pumps, hence lowering the flowing bottom hole pressure
(FBHP) and creating a drawdown at the producing formation. ESP consist of a
downhole pump (a series of centrifugal pumps), an electrical motor which
transforms the electrical power into kinetic energy to turn the pump, a
protector to prevent produced fluids from entering the electrical motor, and an
electric power cable that connects the motor to the surface control panel.Further artificial lift screening was carried out on
the target zones (zone – I, zone – II & zone – III) in X field based on
attributes related to surface and subsurface parameters. These
attributes were categorized as follows: 1.
Reservoir and Fluid Properties:Ø Which
include: Pressure support, Production rates, Temperature, Well Dynamics, Water
cut, GOR, Bubble Point Pressure2.
Well Properties:Ø Including:
Completion Design, Casing size, Well Depth, Well Inclination / Dogleg Severity,
Barriers, Reservoir Access.3.
Flow Assurance:Ø Including:
Asphaltene & Paraffin, Scale, Gas &Water Breakthrough, Corrosive Fluid,
and Treatment (Acidizing).4.
Surface Facilities:Ø Including:
Gas Sources, Electrical Power, Well location, Facility Footprint5.
System Reliability:Considering: Run Life, Logistics, Process Stability,
Training/ Support, Technology Prospects.
attributes will be rated based on the score card for each artificial lift
system (ESP& GL) in each zone. The
score card is shown below;