open hole outflow for co2 injection wells...co 2 - maximum open outflow literature survey some...

OPEN HOLE OUTFLOW FOR CO2

INJECTION WELLS

A Steady State Prediction Tool

Jos van 't Westende, Filip Neele

Snyder Volunteer Fire Department (www.cbs7.com)

WELL OUTFLOW - BACKGROUND

CCS Directive requires operator to provide financial security to cover costs of monitoring, of potential

leakage and corrective measures after handover to authorities

ROAD project, Rotterdam (cancelled 2017): leakage mechanism with largest potential volume emitted

to atmosphere

Probability is (extremely) low

Highest risk during well interventions

Definition of financial security

Need good estimate of potential open-hole outflow rates, during injection period

TNO developed portable tool, with user-defined outflow scenarios

18/06/2019 CO2 - Maximum open Outflow 2

CO2 - MAXIMUM OPEN OUTFLOW

LITERATURE SURVEY

Some guidelines

Thermo-hydraulic model of the well should be available (and calibrated) (DNV-F107, 2017)

Internals of well bore (i.e. injection pipe, valves) may not be considered (BOEM, 2017)

Scenarios may be simplified, if ‘more’ conservative (Nilsen, 2014)

Sonic limitations may be omitted (SPE-174705, 2016)

Computation from bottomhole to topside is most accurate (LSU, 2016)

Use of commercial software (e.g. OLGA or PROSPER)

With & without reservoir effects (e.g. draw down) (Velthuis & Belfroid, 2011)

CO2 - Maximum open Outflow 18/06/2019 3


TNO SOFTWARE TOOL (V0) – PHYSICS, ASSUMPTIONS & APPROACH

CO2 depressurisation causes phase changes

Model uses pressure & enthalpy to cope with

phase change

Model is based on 1-D mass, momentum &

energy balance

Model considers:

JT-effect

Heat transfer

Expansion

CO2 - Maximum open Outflow

Phase change

Flow friction

Gravity

Well inclination

Phase line Isotemperature lines (K)

18/06/2019 4


TNO SOFTWARE TOOL (V0) – PHYSICS & ASSUMPTIONS

Assumptions

Steady flow

Open pipe (no restrictions (e.g. valves))

No drawdown or temperature effects at near-wellbore region

No contaminants (pure CO2)

Liquid/solid is not considered

Inputs

Well trajectory (depth, step out, diameter)

Well & reservoir properties (heat transfer, Pres, Tres)

Multiple 2-phase models



TNO SOFTWARE TOOL (V0) – PHYSICS & ASSUMPTIONS

Approach

Compute fluid property tables as function of pressure & enthalpy using Refprop v9.1 of NIST

Phase diagram, temperature, density, viscosity, speed of sound, (d/dP)h, (d/dh)P

Numerically compute from bottomhole to topside (pressure & enthalpy)

Goal seek algorithm:

Topside pressure decreases with increasing flow

Maximise flow while keeping:

Topside pressure above topside pressure setpoint, and

Flow velocity below speed of sound



TNO SOFTWARE TOOL (V0) - GUI

Input fields, grouped

Well properties

Reservoir properties

Rock properties

Well trajectory

Outputs

Maximum flow rate

Outflow temperature

CITHP

Seek algorithm progress

P, T & velocity profile

CO2 - Maximum open Outflow 18/06/2019 7 CITHP: closed-in tophole pressure

0 50 100 150 200 250 3000

20

40

60

80

100

120

140

160

180

Pres

[bara]

Wm

ax [

kg/s

]

ID = 3"

ID = 4"

ID = 120mm

ID = 150mm


TNO SOFTWARE TOOL (V0) – EXAMPLES (1/3)

Examples on diameter effect with various

Pres using the Hasan & Kabir model

Closed symbols: two-phase flow near

wellhead

Open symbols: only single phase flow

more accurate

Trock,bottom = 70 °C

Tres = 100 °C

Ptop = 1 bar

TVD = 2000 m

Roughness = 50 m

Perfect reservoir CO2 - Maximum open Outflow 18/06/2019 8

TVD 2000 m



Examples on diameter effect with various

Pres using the Hasan & Kabir model

Closed symbols: two-phase flow near

wellhead

Open symbols: only single phase flow

more accurate


Tres = 100 °C

Ptop = 1 bar

TVD = 3000 m

Roughness = 50 m

Perfect reservoir CO2 - Maximum open Outflow 18/06/2019 9

TVD 3000 m



Examples on effect of non-zero flow

resistance in reservoir with various Pres

using the Hasan & Kabir model

Pres2 – PBH

2 = A Q

Values of A representative of good (A=1)

to medium (A=10) quality well / reservoir


Tres = 100 °C

Ptop = 1 bar

TVD = 3000 m

Roughness = 50 m

ID = 120mm


FLOW RATES, VOLUMES

EXAMPLE FOR ‘PERFECT’ RESERVOIR

Reservoir

pressure

Flow rate

ID 3”

(kg/s)

Volume

ID 3”

(kt)

Flow rate

ID 120 mm

(kg/s)

Volume

ID 120 mm

(kt)

20 bar 2 20 5 40

50 bar 4 30 10 80

100 bar 6 50 18 140

200 bar 12 90 40 320

300 bar 20 160 65 510

CO2 - Maximum open Outflow

Reservoir depth 3000 m (example 1/2)

Duration of flow / response time: 3 months

Rounded to nearest 10 kt

18/06/2019 11

CONCLUSIONS

Open hole outflow: likely to be leakage scenario with largest leaked volume

Highest risk during well interventions

Outflow tool provides outflow rates for scenarios that can be defined by user

Results benchmarked on OLGA computations

Provide basis for storage permits

Outflow rates

Increase with increasing reservoir pressure

For response time of 3 months: volumes up to ~0.5 Mt for ‘full’ reservoir (worst case)

Must keep in mind very low probability of occurence

No free outflow events from CO2 wells observed



POSSIBLE NEXT STEPS TOWARDS V1

Portability improve sharing of prediction tool

Reservoir drawdown & temperature effects

Effect of impurities can affect outflow rate & temperature

GUI improve workability (ease of use (parameter study) & relevant outputs)

User guide improve workability


THANK YOU FOR YOUR

ATTENTION

Take a look: TNO.NL/TNO-INSIGHTS


TNO SOFTWARE TOOL (V0) – COMPARISON WITH OLGA

60 cases, varying:

Inclination (90, 75, 60, 45 & 30deg from vert)

Pipe diameter (100 & 150 mm)

Pdownhole (20, 100, 300 bara)

Heat transfer (0 & 10 W/m2K)

Trock,top = 10 °C


Tres = 123 °C

Ptop = 1 bar

TVD = 3000 m

Roughness = 50 m



TNO SOFTWARE TOOL (V0) – COMPARISON WITH OLGA

Pres = 20 & 100 bara : single phase only

small variations

Beggs&Brill give lowest estimate of Max outflow

Relative variations between models seem not

case depend.

Hasan & Kabir model deviate at most 3% from

OLGA results


open hole outflow for co2 injection wells...co 2 - maximum open outflow literature survey some...

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