Online Field-Wide Gas-lift Optimisation

1

e-petroleumservices.com

Online Field-Wide Gas-lift Optimisation

Dr Alasdair S BrownTechnical ManagerEPS Americas Inc

2


Presentation Structure

• Introduction• Single Well vs Field Wide• Online vs Offline• Case Studies

– Latin America– Middle East

• Conclusions• Questions

3


Single Well

• Single Well Gas Lift Optimisation– Valve Spacing– Injection Depth– Valve Performance– GL Injection

Pressure

– Qgaslift

– CHP

4


Single Well

• Conditions change– GL is inherently flexible– Design in flexibility

• Single well optimum– Well performance curve– Different for each well– Not necessary optimal

for system

5


Gas Lift Optimisation

Gas Lift Compressor

Well

Well

Well

Well

Equal Gradients Method

Common Pressure

6


Field Wide Optimisation

• Field Wide Gas Lift Optimisation– Distribution of Gas to competing wells– Pressure losses in gas lift distribution system– Pressure losses in production system– “Closing the Loop”

• Total system modellingTotal system modelling– including produced gas reinjection– Compressor performance

– Offline/Online

7


Why Online?

• Large Number of Wells• Complex optimisation problem• Reduce cycle time

– Optimisation-to-implementation– Engineer’s time concentrated on value adding tasks

• Goals– Automate Process– Automate Repetitive Tasks– Optimise

8


Sustainable Production Optimisation

Time

Incr

ease

d V

alu

e O

ver

‘Do

No

thin

g’

Simple Manual Optimisation

Complex Manual Optimisation (Offline GLO)

Complex Automated Optimisation (Online GLO)

9


Automation & Optimisation• Off-line

– Data input manually into system model– Results from system model implemented manually

• Open loop– Data input automatically into model from SCADA– Results from model implemented manually

• Closed loop– Data input automatically into model from SCADA– Results from model implemented automatically via

set point controllers– Operator review may be required to ensure that

implemented results are “sensible”

10


Off-line Optimisation

Optimiser

Field

OPERATOR • Advice• Approval• Implementation

Manual Data Input Data Output

11


Open Loop Optimisation

Optimiser

FieldOPERATOR • Advice• Approval• Implementation

Automatic Data Input Data Output

12


Closed Loop Optimisation

Optimiser

Field

OPERATOR •Advice•Approval•Implementation

Automatic Data Input

Data O

utp

ut

SetpointControllers

13


Case 1: PdVSA On-Line

– SCADA data automatically loaded to give current block valve and compressor status and to constrain the optimisation to stay close to existing operating conditions

– Price/cost and equipment constraint data loaded from Corporate databases

– Gas injection well set-points sent directly to SCADA controllers (after production operator review as a block)

– Recommended pressure control valve set-points and compressor operating conditions sent to production operators in open-loop advisory messages

– Results stored in central database for access by other applications.

14


PdVSA Systems Overview

PROCESS CONTROL

CENTRAL CONTROL

OPTIMISATION

CIS

RTU, PLC..

SCADA

ASMS, WTO, NN, OM&S, IS

CENTINELA, SIAL, SICOT..

15


Integration Schematic

16


DataReconciliation

DGO

Well ModelRecalibration

LegacyData

Systems

Pri

m.Changes

NeuralNets

Well

Test

System Geometry

ASMS

OM&S

Decoupled

CDMS

One iGES Server per BU

iGES-basedapplications

OracleIntermediate

DataBase

MiddlewareTransaction Services

SCADA ServerSCU 2

Real Time History

SCADA ServerSCU 7

Real Time History

PIHistorian

Crude/WaterTreatment

&Water Injection

Dynamic LeakDetectionPI Decoupled

from PRAP

Databaseservers

CDB

MasterRecollectors

PI API

SCADA ServerSCU 1

Real TimeHistoryAverageData

Real Time

SCADA ServerSCU 6

Real TimeHistoryAverageData

OPC

ABB Simcon

KBC UpRight EPS

Valmet

Stoner

ODBC

COM

System Architecture

17


Process Control

Central Control

Optimisation

Corporate Systems

PdVSA Online GLO

GLO

18


Process Control

Central Control

Optimisation

Corporate Systems

The Online GLO Application

RTU/PLC

Optimiser

Database

SCADA

Input Output

Input Output

19


Online GLO Daily Operation

GLO

GLO is executed...

Gas lift rates andrecommendations downloadto SCADA

Gas Lift Well

MiniPlantas

Compressors

The results are evaluated...

Approval atSupervisory level

The SCADA Operatoraccepts the gas lift ratesand carries out adjustments

22


La Salina Online

Tuned Well ModelsGenerate Operating PtWellhead PerformanceCurveWells in FlowgroupsFlowgroup Performance

SurfacesHP Gas Lift NetworkLP Gas GatheringNetworkComplete Network

23


Field Implementation Results

25


POIS• POIS = Production Operation Information System• Northern fields of Kuwait• Performed by consortium including EPS, Aspentech, Daelim• EPS role was to provide the optimization software, software integration

and detailed engineering models for five fields in North Kuwait. • The fields included 197 wells (411 well strings)

– 33 water injectors, – 91 gas lifted producers and – 30 produced with ESPs.

• The wells and fields are connected through a complex network allowing wells to be switched between high, medium and low pressure as well as ‘wet’ and ‘dry’ separator trains

• Total production 600 Mstb/day

26


Design Brief

• Hydraulic model of GL Distribution System• Compressor Station behaviour and Performance

– Power turbines, compression, gearboxes, intercoolers, gas recycling

– Surge and stonewall constraints

• Multiphase Flow• Scalable to >1000 wells• Optimise non-hierarchical networks• Online Integration with

– Production Management System– DCS/SCADA System

27


Objectives

• Data acquisition via SCADA to MIS (Aspentech)

• GL optimisation for new GL wells– GL being installed following water injection

• Automatic acquisition of WT data • Automatic well model recalibration• Automatic online GL optimisation calculation• Manual setting of optimised setpoints

(initially)

28


PAS Concept

PAS

NewWellTest

WellFloWell Model

Compare with

trend

Engineerintervention

Rerun orretune

POIS

Fail

Pass

Manual Model Retune

Automatic Model Retune

Rerun Welltest

Data Transfer

Past data

29


GLO Concept

GLO

ReO System Model

POIS

Network model

Wells Wells Wells Wells Wells

InitiateGLO run

GetUpdated

well models

Generatewell

performanceRun GLO

Convert tochoke

settings

New SettingsNew gas allocation

30


Implementation

• Well modelling of all 411 wells (WellFlo)• Construction and tuning of network Model

(ReO)• Automatic tuning of Well models• Automatic GL optimisation• Integration with Aspentech MIS• Model maintenance and development

31


Important Issues Identified

• Data Quality– Well data– production data– Surface network data

• Business processes– building use of POIS model into std. procedures– model maintenance– model enhancement

• Compressor optimisation• Multistage separation optimisation

32


Network Config Modelling

Individual fields (viz., RA, SA, RQ, AD & BH) modelled as separate sub-sheets

Each GC has 7 headers that can take inflow from any or all wells

All fields interconnected through 3 Gathering Centres: GC-15, GC-23, and GC-25

33



Multiple GC & MF options for all the wells made network very flexible to accommodate any future flow path definition

Optimiser easily handled this huge network - over 40,000 objects!

34


SCADA & POIS

Well Head PressureFrom 217 Wells

GC SCADA GC DCS

GC RTDB(POIS)

All DCS DATATRANSFERRED

RADIO LINK

PMDBALTAMEER

(POIS)

FINDER WELL INFORMATION

Business Process ExplorerGUI

WellFlo Reo&

WellFlo

Maintain Well Models(Administration of)

PAS

Hydrocarbon AccountingMaterial Balance

GLO

User

35


Top Level Network

36


Raudhatain-[RA]-GC15&GC25

Abdali-[AD]

Ratqa-[RQ]

Bahra-[BH]

Sabriyah-[SA]-GC23

C-GC15 C-GC25 C-GC23

Abdali:

16 Wells

to 2 GC

via 13 6in linesRatqa:

20 Wells

to 2 GC

via 36in & 10in lines

Raudhatain:

195 Wells

to 3 GC

thru’ 7 MF each

Sabriyah:

142 Wells

to 1 GC thru’ 7 MF

Bahra:

5 Wells

to 1 GC thru’ 7 MF

378 producers with choice of producing into any of 3 GCs through any of 21 MFs


37


RA Field Network

38


Lift-Gas System

5x7 Possible inputs from RQ & AD fields

9 Sub-sheets holding 20-25 wells each

7x3 MF interconnecting all 194 wells across the field

7x3 MF outlets to production terminals

Lift gas to SA field


39


NP & GLwells (FG)

Multi-header choice for lift-gas

at present & for future

Multi-MF choice for production

at present and for future


40


GL Well Performance Surface Data

41


Conclusions

• KOC currently producing to quota– Current capacity higher than quota

• (how much higher is unknown)

– However additional production can be allocated to NK– Cost reduction is additional benefit

• Reduction in admin overhead• Reduction in flaring• Potential reduction in new well requirement• Network reconfiguration

• Work practices need to change to extract full value from the system

42


POIS project

• Client - Kuwait Oil Company• Year of Contract Award – 2000• Projected Value Generated:

– $100 million - $175 million per annum (projected)

43


Questions?

Documents

Online Field-Wide Gas-lift Optimisation