ADCO - Bab Far North Field CO2 Injection Pilot Project

Date: 5th May 2015

Syed Ajmal HaiderSr. Process Engineer

Project Objectives Background Concept Project Overview/Scope Process Design Basis Process Description Operating and Control Philosophy Startup Philosophy WAG Change Over Philosophy Venting, Relief and Depressurizing

Philosophy

Presentation Outlines Pigging Philosophy Interfaces With NEB Tie-ins at RDS-8

Project Objective Collecting the necessary technical data to assess CO2

injection effectiveness for enhanced oil recovery from TH ’B’ which will be used to carry out feasibility study of a full scale CO2 EOR development in BAB.

To reduce the CO2 emission in the environment.

1. Mechanism to Reduce the CO2 Emission to Environment

Carbon dioxide (CO2) capture and sequestration (CCS) is a set of technologies that can greatly reduce CO2 emissions from power plants and large industrial sources. CCS is a three-step process that includes: Capture of CO2 from power plants or industrial processesTransport of the captured and compressed CO2 (usually in pipelines).Underground injection and geologic sequestration (also referred to as storage) of the CO2 into deep underground rock formations.

Background Concept

2. Oil Recovery Methods

Recovery is the heart of oil production from underground reservoirs. The amount of oil produced worldwide is only one third of the total oil available according to the Department of Energy U.S.A. Using EOR techniques, we will be able to produce more oil as the demand increases while we have a shortage in the supply.

1. Oil Recovery Methods

Enhanced Oil Recovery (EOR) – CO2 Injection

EOR processes attempt to recover oil beyond secondary methods (30 - 50 %) up to 80%

Tertiary recovery or EOR targets immobile oil (that oil which cannot be produced due to capillary and viscous forces).

Enhanced Oil Recovery (EOR) - CO2 Injection method provides additional benefit of Carbon Capture and sequestration (CCS) to reduce CO2 emissions as well

1. CO2 Injection Facility

Maximum Capacity of CO2 Pipeline is 41.5 MMSCFD Maximum CO2 injection capacity of each of the Injection Well

is 10. 375 MMSCFD Maximum water injection capacity of each of the Injection

Well is 6000 BWPD

Project Design Basis

1.1. Pipeline Design Capacity

CO2 Pilot injection Facility provided for following two flanks North Flank East Flank

1.2. Fluid Composition

Components Units Value

CO2 Mole % More than 98 %

H2 Mole % Less than 0.25

CO Mole % Less than 0.18

CH4 / HC Mole % Less than 0.10

N2 Mole % Less than 0.05

H2O lb/MMSCF 40 (Nor) / 80 (Max)

H2S ppmv Less than 400

Process System Description

1. CO2 Supply and Injection System Dense phase CO2 supplied from MASDAR to Rumaitha at 210-235

barg. CO2 supplied to Bab either from suction (210-235 barg) or from

discharge (265 barg) of the Rumaitha booster pumps and enters the CO2 pipeline via pig launching facility

Online moisture analyser with high alarm and CO2 leakage detectors provided on CO2 pipeline to BAB

BVS-1 /BVS-2 provided at ~24 km and ~48 km for sectionalizing of CO2 pipeline.

CO2 injection heaters are provided at each flank to keep CO2 injection temperature above 38°C during winter.

Process description of the major facilities provided as follows:

2. Hydrocarbon Gas For Start-up/CO2 Displacement Hydrocarbon lift gas used for initial pressurization of 70 Km CO2

pipeline Hydrocarbon gas is available at high pressure of 408 barg which is

let-down to the requirement when passes through pressure reduction station at BAB Launcher area in Rumaitha

A dedicated Start-up Electrical heater provided to heat up the hydrocarbon lift gas to maintain 80 °C to protect CO2 pipeline against low temperature exposure during start-up operation ( to avoid pipeline fracture/cracking).

Hydrocarbon lift gas also used for displacement of CO2 from the pipeline in case of CO2 pipeline maintenance required.

3. Water Injection System Both CO2 injection pilot flanks will be switched alternatively to water

injection cycle every 6 months. Injection water taken from existing water injection cluster (Cluster 30 and 31).

WIC-31 shall supply injection water to North Flank and WIC-30 shall supply injection water to East Flank

Water Injection Pressure downstream of well head choke will be approximately 138 barg.

During CO2 injection cycle, the brackish water in injection pipeline will be drained in a pit and pipeline will be flushed twice with sweet water to preserve the water pipeline.

Inhibited water will be filled in water pipeline dosed with Combo chemical (Oxygen scavenger/biocide).

4. Oil Producer System There is one dedicated oil producer well at each injection flank to

produce and to monitor the performance of CO2 injection effectiveness

Two separate flow lines from both oil producer well connected to RDS8 and buried underground.

Both flowlines are provided with a provision of mobile pigging facility ( Pig Launcher and Pig Receiver) for cleaning and inspection purpose.

A dedicated MPFM and Manifold provided

5. Chemical Injection Systems Provided Mobile Methanol Injection System – Common for both flanks at CO2

Injection wells Oxygen Scavenger / Biocide Injection system – one at each flanks for

Water Injection Pipeline Asphaltene / Corrosion inhibitor Injection system – one at each

Producer well Antiscalant (scale inhibitor) Injection System – one at each Producer

well

6. Utility Systems Two CO2 Vent Stacks for BVS-1 and BVS-2 each Nitrogen Package (Purging & Pressurization) Mobile Flare Package - Common for both BVSs

CO2 Pipeline Route

Operating and Control Philosophy

1. CO2 Pipeline– Operating Philosophy

The intention is to operate CO2 Pipeline facility in a safe and efficient manner.

The CO2 Pipeline will be remotely operated facility by ADCO operations in BAB CDS / RDS-8 Control Room.

Functionally, the CO2 pipeline network & Well injection system is similar to the gas injection network.

The main process parameters to be monitored are pressure, temperature and moisture content in the CO2 pipeline.

1.1. General

Phase Behaviour of Pure CO2 The triple point is 5 Bara, -56.7 °C. The critical point is 72 bar a, 31.1 °C.

Phase Behaviour of CO2

Phase Behaviour of CO2 Cryogenic nature of CO2 due to its highly negative Joule-Thompson coefficient Requires careful consideration in the design of CO2 pipeline related to

depressurization from high pressure to low pressure and also during start-up of CO2 pipeline whereby high differential pressure across the valve exist.

During both operations (depressurization and start-up which are independent activities), low temperature is experienced by pipeline due to Joule-Thompson effect.

Furthermore, while depressurizing, the triple point of CO2 could be reached, resulting in the formation of solid CO2 (dry ice).

Disposal of the CO2 stream into the atmosphere, especially when it contains H2S is a health issue with the potential for personnel injury and CO2 emission limits.

The CO2 pipeline depressurising (blow down) should consider the associated health issues as the Bab Far North Injection gas stream contains up to 400 ppm H2S.

1.2. Mode Of OperationCO2 pipeline is designed to handle the following conditions/ scenarios

SCENARIO DESCRIPTION

SCENARIO-1Max. Operating capacity as 41.5 MMSCFD. It occurs when all Rumaitha injectors are down & flow diverted to BAB CO2 pilot Injection project

SCENARIO-2Operating capacity as 32 MMSCFD. It occurs when some of Rumaitha injectors are down and flow diverted to BAB CO2 pilot injection project

SCENARIO-3Operating capacity as 16 MMSCFD. This scenario is normal case and it occurs when both BAB CO2 flanks and Rumaitha injectors are working.

SCENARIO-4Operating capacity as 8 MMSCFD. This scenario occurs when only one of the BAB injector is working and all the Rumaitha injectors are working on CO2 injection mode.

1.3. WAG Change Over The WAG or Water-Alternate- CO2 technique is a combination of

two traditional improved hydrocarbon recovery techniques; water flooding and CO2 injection.

Main advantages of the WAG process include higher CO2 utilization, reduced CO2 production and greater ultimate recovery of oil

The WAG injection well will have water and gas injection alternatively with changeover occurring every 6 months.

The changeover from one to the other will be manual operation and will take place close to the wellhead.

Methanol injection is required during change over from CO2 injection to water injection for 1 hour or as the need arises to avoid hydrate formation.

During CO2 Injection cycle in either North Flank/East Flank, water inside pipeline/piping shall be preserved by draining the brackish water to drain pit to avoid corrosion.

Once draining operation is completed then the pipeline/piping will be flushed with sweet water using sweet water tanker pump.

Oxygen Scavenger/Biocide is to be injected at the discharge side of sweet water tanker pump

Sweet water will be supplied by tanker and is to be brought to the each flank before start of water preservation operation.

A dedicated Oxygen Scavenger/Biocide injection package at the each flank is provided to inject the chemical during water preservation operation.

The inhibited water will be filled in water pipeline after dosing with Combo chemical (Oxygen scavenger/biocide) to avoid corrosion.

1.4. Water Preservation System

The CO2 flow to CO2 Pipeline is controlled by FCV at the discharge of Booster pumps at Rumaitha during all modes of operation.

The Gas lift Pressure from Rumaitha is reduced via Pressure Reduction Station during start-up and required gas lift temperature is maintained by start-up electrical Heater.

At each flank, The dense phase CO2 temperature is maintained by respective CO2 injection heaters and CO2 injection rate is regulated by choke valves at each injection well

During water injection cycle, Water flow from the cluster 30/31 will be controlled by respective control valves at water injection piping of the injector well.

2. CO2 Pipeline – Control Philosophy

Start up Philosophy1. CO2 Pipeline Start up Philosophy:The following systems/activities are need to be completed before commencement of start-up operations:Fire Protection System is commissioned and started.CO2 Injection pipeline is completely air free and purged with N2.Adequate pressure is available in Water injection header/pipeline

The start-up of CO2 pipeline is based on the following scenarios: Initial Start-up : Start-up for the first time after the mechanical completion and pre-commissioning/commissioning checks)Pipeline Start-up in Pressurized Condition after a short shutdownStart-up after shutdown of pipeline on ESDStart-up after a major work-over or maintenance

Start up Philosophy

1.1. Initial Start-up

The sequence of activity will be as follows: Start-up electric heater and associated piping is under positive pressure at say 20 barg with nitrogen.Open the bypass around the battery limit valve of the HC source gas (HC gas @ 408 barg at B/L) and line-up Start-up Electrical Heater.Heat the HC lift gas to 80 °C and start pressurizing the piping/pipeline section up to manual isolation valve to 90 barg.After pressurization of piping section up to manual isolation valve start pressurization of CO2 pipeline by opening of pressurization globe valve to 90 barg and open pipeline shutdown valve (SDV). The HC gas starts filling the pipeline up to 90 barg. The nitrogen will be vented at the well end by opening the vent valves. The pressure starts building up in the pipeline.

1.1. Initial Start-up Continue till the pressure reaches about 90 bar inside the CO2

pipeline, close the HC gas battery limit isolation valve and stop the HC gas supply. Close the isolation valves on HC gas supply line, downstream of HIPPS.

The pipeline is now ready for introduction of CO2. The HC gas will be displaced and pushed into the reservoir by CO2. Start the CO2 booster pumps in recycle mode. Open the battery limit isolation valve slowly for CO2 supply. The pipeline hydrocarbon gas will start getting displaced pushed by

incoming CO2. As the pressure in the pipeline reaches a value of about 200 bar (as

read from the pressure indicators at well head end), open the choke valve manually and route the HC gas into the well.

1.2. Pipeline Start-up in Pressurized Condition after a short shutdown

During short duration shutdown initiated by operator intervention, the pipeline will be boxed-up under normal operating pressure. As the CO2 is available at the requisite pressure and the pipeline is pressurized, the operation can be started by opening the battery limit valve. It should be ensured that all the block valves downstream of the line are in open position. Finally open the choke valve to line up the CO2 injection.

1.3. Start-up after shutdown of pipeline on ESDScenario-1: In case pipeline is shutdown due to any ESD activation, and the shutdown is for a short duration and the pipeline is isolated with the CO2 boxed-up in the pipeline. The philosophy for start-up in this condition will then be similar to the one described under scenario 1.2 above.

1.3. Start-up after shutdown of pipeline on ESD

Scenario-2: If a prolonged shutdown is envisaged and it is required to evacuate the CO2 from the pipeline through HC displacement, the CO2 pipeline will be pressurized with nitrogen to 1 - 2 barg and start-up of CO2 pipeline will be initiated following same procedure described under scenario 1.1 above.

1.4. Start-up after a major work-over or maintenance

This Scenario occurs when the pipeline start-up follows after maintenance on a section of CO2 pipeline. This Scenario considers pipeline sectionalizing for carrying out some major work over or maintenance on a section of CO2 pipeline post CO2 displacement with HC gas while maintaining the other pipeline sections in pressurized condition with HC gas. The HC gas from CO2 pipeline section requiring maintenance is vented and flared using Mobile Flare Package.

WAG Change Over Philosophy The WAG injection well will be injected water and gas alternatively with

switchovers occurring every 6 months. The changeover from one to the other will be a manual operation and will take place close to the wellhead with the help of positive isolation as shown in below schematic.

When switching from CO2 injection to water injection, the well tubing need to be depressurized from 200 barg pressure at 38 C or well settle out pressure to 138 barg pressure at 32.7 C which is the required water injection pressure. The well tubing will be depressurized using vent line as shown in Schematic. Prior to depressurization of well tubing, the line which is marked with green and orange colours need to be pressurized with nitrogen up to 90 barg to provide a back pressure for CO2 in order to prevent solid CO2 formation as well as avoid exposing the piping to low temperature.

WAG Change Over Schematic

1.1- Switching from CO2 Injection to Water Injection Isolate the CO2 supply from the CO2 Pipeline by closing wellhead

injector battery limit double isolation valves and SDVs. Isolate the CO2 supply from Flowline to the wellhead by closing

isolation valves downstream of CO2 injector choke and closing Wing valve on wellhead.

Maintain CO2 under pressure in the CO2 pipeline in boxed up condition during water injection cycle.

Check and ensure that water supply is isolated on water line at wellhead injector battery limit isolation valve.

Depressurize and purge the Flowline section marked in green in the Schematic shown in section 5.0.

1.1- Switching from CO2 Injection to Water Injection Pressurize Flow line section portion marked in green in the

Schematic shown in section 5.0 with nitrogen up to 90 bar. Open Wing valve, Master valve and SSSV. Depressurize the well tubing using vent line marked in Orange color

in the Schematic and closely monitor temperature and pressure. When the pressure reaches to 138 bar stop depressurization by closing Wing valve and Master valve.

Depressurize and purge with nitrogen the Flow line section portion marked in green in the Schematic to ensure entire CO2 is vented.

Switch the swing elbow and removal spool piece removal spool from CO2 supply to water supply line. Install blind flanges on both ends of the CO2 Flow line at the location where the swing elbow and spool piece spool is removed.

Override PTs High/low pressure signals to operate the injection Wing valve and Master Valve.

Make sure that mobile methanol injection package is ready to inject methanol.

Check that the injection water is available at the double isolation near injector wellhead. Vent any gas pocket in the water injection wellhead piping upstream of battery isolation valves.

Start Mobile Methanol injection package for injecting methanol to water piping.

Slowly bring water flow up to the required value.

1.1- Switching from CO2 Injection to Water Injection

1.2- Switching from Water Injection to CO2 Injection Isolate the water supply to the injector wellhead by closing the wing

valve and the isolation valve at wellhead. Close the isolation valve located near to the wellhead to that isolates

well piping from the water injection Flowline. Drain the entrapped water inventory between wellhead Wing Valve and

isolation valve located near to the wellhead through low point drain valve.

Ensure that the double block and bleed (DBB) valve on water side near to wellhead fence area are in closed position. Drain the wellhead water piping.

Remove the drop out spool piece and swing elbow spool out connection from the water supply line. Install blind flanges on both ends of the water supply line from where spool piece and swing elbow spool is removed.

Ensure that choke valve on CO2 injector flow line and isolation valves downstream of choke on CO2 flow line are in CLOSED Position.

Ensure pressure transmitters are in “Override PTs” mode on the flow line.

Connect swing elbow and spool piece from water line to CO2 injector flow line. While connecting the swing elbow and spool piece, keep bleed valve open which is located on the CO2 injection line to release any trap-in pressure in between the double block valve. Install the same removable spool piece from water line to CO2 injector flowline.

1.2- Switching from Water Injection to CO2 Injection

After switching of the swing elbow removable spool piece from water supply to CO2 supply, the CO2 flow line shall be checked for any leaks by nitrogen pressurization.

After leak checking, pressurize the line by nitrogen to 90 barg. High/Low pressure override signals should be changed to

“NORMAL”. Open the choke valve on CO2 injector flowline and allow dense

phase CO2 to displace water in well string. Slowly increase flow rate until desired value is reached.

During CO2 injection cycle dormant water pipeline/piping are to be preserved with sweet water injected with Oxygen Scavenger/Biocide.

1.2- Switching from Water Injection to CO2 Injection

Pigging Philosophy1. In-Service Cleaning On the completion of construction phase of the project, pipeline may

accumulate with water, corrosion products (rust scale) and other deposits which must be cleaned out to maintain efficiency of operation. Therefore, pigging of CO2 pipeline with cleaning type pig will be done initially.

However, during normal operation, dehydrated CO2 (near bone dry condition) will flow through pipeline and water accumulation is not anticipated. Therefore, in service pigging is not required for this case.

Pigging Philosophy2. Intelligent Pigging The recommended inspection pigging frequency based on industry

experience is one run during the line commissioning, then after the first year of operation as a baseline and thereafter every 3 to 5 years, depending on initial results and subsequent integrity assessments.

The following mediums will be utilized for intelligent pigging: Water HC lift gas CO2

Pigging Philosophy2.1 First Intelligent PiggingThe intelligent pigging will be carried out initially with water to collect base-line data after completion of hydro-testing and pipeline cleaning before CO2 introduction in pipeline at minimum operating pressure which will be confirmed by pipeline inspection vendors. All necessary arrangements will be ensured to dry and preserve the CO2 pipeline completely when water is used as a motive fluid for intelligent pigging.

2.2 Subsequent Intelligent PiggingDuring subsequent intelligent pigging after 3 – 5 year time for integrity assessments, same service fluid (CO2) will be used as a motive fluid for the pigging operation at the CO2 pipeline operating pressure and pigging inventory will be routed to CO2 injection wells.

Pigging Philosophy

During any major maintenance activity of CO2 pipeline, the CO2 will be displaced into the injection well at CO2 pipeline operating pressure using HC Lift Gas and a separation pig will be used between CO2 and HC gas. Separation pig is useful to correctly determine the interface and also to reduce the length of interface layer. However CO2 displacement with separation pig can be avoided if the environmental impact study accepts and approves the safe venting of CO2 pipeline section under maintenance.

3. Separation Pigging For CO2 Displacement

Pigging Philosophy

The CO2 from the pipeline will be displaced using HC Lift Gas and a Separation Pig will be used between CO2 and HC gas. The CO2 will be displaced into the injection well. As the pig approaches the receiver station at North Flank, the MOV located on bypass line will be kept open and MOV located on the receiver inlet will be throttled to facilitate flow of gas through the pig receiver. This operation is continued for about 10 – 15 seconds after the pig is received in the receiver. This is to ensure complete displacement upto MOV located at the inlet of pig receiver. At this point the displacement process is complete and all the relevant valves on pipeline need to be closed.

3. Separation Pigging For CO2 Displacement

Isolation and Maintenance PhilosophyThe Process units/ systems which will have isolation requirements as a part of this Project are as follows:

I. Flow lines / CO2 Pipeline

II. Package items Electrical heaters Chemical Injection Skid MPFM

III. Tie-ins Tie-in of CO2 pipe line to Injection Well Tie-in of CO2 pipe line with Rumaitha NEB

Isolation and Maintenance Philosophy Tie-in of Hydrocarbon Gas Lift line with Rumaitha NEB Tie-in of oil producer flow lines with RDS Utilities – Nitrogen Water injection pipeline Vent & Blowdown tie-ins

IV. Pig Traps

Vent, Relief and Depressuring Philosophy The normal relieving strategy in case of depressurization, relief or venting

scenario applied to hydrocarbon releases of collecting gases in a flare knock out drum and venting via a flare stack cannot be applied for CO2 venting.

Cold CO2 is heavier than air, and so if large quantities of CO2 were released via a vent stack with inclement benign weather conditions, the CO2 would settle down back to on grade level and potentially present a significant asphyxiation suffocation risk.

Also when Dense Phase CO2 is letdown from high pressure to atmosphere, Joule Thompson cooling effect drops the CO2 temperature to around -78° C and so a mixture of solid CO2 (dry ice) and gas is produced.

High Pressure vent will consider controlled pressure reduction of CO2 in order to minimise significant temperature drops upon release to atmosphere.

Scenarios For Depressurisation, Venting & Relief For Bab CO2 Pipeline Blocked Conditions External Fire General Thermal Relief General Maintenance Venting

Areas Requiring Venting And DepressurizationVenting and Depressurization is applicable for the following areas/sections of Bab CO2 Injection Pilot Project:Pig Launcher at RumaithaBlock Valve Station-1 (BVS 1)Block Valve Station-2 (BVS 2)Pig Receiver at Bab North FlankCO2 Injectors

Interface with NEB Following are the interfaces with NEB Rumaitha facilitiesInterface with CO2 pipeline: CO2 is supplied to Bab either from suction (210-235 barg) or from discharge (265 barg) of the booster pumps (part of NEB facilities).Interface with HC lift gas: Hydrocarbon lift gas will be supplied from NEB facilities. Hydrocarbon lift gas will be used for start-up pressurization and for CO2 displacement. BAB operating team is to co-ordinate with NEB operating team for line-up of HC lift gas to BAB facilities to perform above activities.PLC Interface: The BAB RTU/PLC shall be interfaced with Rumaitha Cluster–N PLC by serial interface RS-485 Modbus for the alarm signal exchange for monitoring and operator intervention which shall be fibre optic based.There is no ESD interface between BAB RTU/PLC and Rumaitha Cluster–N PLC.

Interface with NEB The following status indications have been imported from the Rumaitha Cluster 14(N) to the BAB CO2 injection facility.Flow indication from the discharge of CO2 Booster Pump (FI-3114-01);Total CO2 flow indication from Masdar (FI-3114-02A/02B);CO2 Booster Pump On/Off status indication (XI-3114-01/02/03);ESD 1, complete Rumaitha Cluster 14(N) shutdown status signal;ESD 2, Rumaitha Cluster 14(N) production and injection shutdown status signal.

Interface with NEB The following status indications have been exported from the BAB CO2 injection facility to the Rumaitha Cluster 14(N).Start-up Electric Heater On/Off indication (XI-3901-02);Pressure control valve (PCV-3901-01) pressure indication (PI-3901-01);HC Lift Gas HIPPS valve (SDV-3901-03/04) Open/Close indication (SZIL-3901-03/04 and SZIH-3901-03/04);CO2 HIPPS valve (SDV-3901-05/06) Open/Close indication (SZIL-3901-05/06 and SZIH-3901-05/06).ESD 1, complete BAB CO2 injection Cluster shutdown status signal;

Interface with NEB The following status indications from the Masdar facility have been provided in the BAB CO2 injection facility and Tabulated below in Table 13.1

Sr No. Tag No SIGNAL DESCRIPTION

1 1501-XA-XXX2 CCF (Carbon Capture Facility) ESD Alarm (CCF Emergency Shutdown)

21501-XA-XXX1

Confirmed CO2 Detection Alarm (CO2 Release Warning)

3 1501-XA-XXX3 CCF trip Alarm (CCF Trips)

4(1501-FI-4151 AA/BA)

MMscf / TonsCO2 Daily Average Flowrate Indication

5 1501-AI-4150 AA / AB /AC /AD/AE / AF

Gas Composition - H2S /CO2/H2/CO/CH4/N2 respectively.

6 1501-AI-4149 A Gas Composition - O2

7 (1501-XA-XXXX) Moisture Composition - H2O

8 1501-PI-4162 PIT (Pipeline Inlet Pressure) 9 1501-PAL-4162 PIT (Pipeline Low Pressure Alarm)

10 - ESI 1 Trip Alarm11 - ESI 2 Trip Alarm

2” Blow Down line from Manifold to Existing Header (TP 17) 2” Drain line from MPFM to Existing Header (TP 18) 2” Vent Gas Line from MPFM to Existing Header (TP 19A/B) 10”Producer line connecting to 24” Existing Production Header (TP

20A/B) 2” Chemical Inj. line from Existing Header to Manifold’s Production &

Test Headers (TP 21) 2” Nitrogen line from Existing Header to Manifold’s Production, Test

& Blow Down Headers (TP 102)

Tie ins at RDS-8

Thank You