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Master

ANNULAR PRESSURE MANAGEMENT IN SPDC

ASSESSED INTERNSHIP PROJECT

DECEMBER 2012

ANDREW OFOEDU

UIG/T/DET

INTERN, PRODUCTION TECHNOLOGY DISCIPLINE.

1



Master

OUTLINE

Objectives and Deliverables

Relevance to business

Overview

Methodology

Findings

Challenges

Key Stakeholders

Learning

Conclusion/Broader Implications

Recommendation

DECEMBER 20122



Master

PROJECT OBJECTIVES

Document the identified issues for

annular pressure management and

line of action to mitigate future

occurrence.

Deliver an optimized procedure for

annular pressure management and

sustainability plan to asset owners.

Demonstrate a good understanding of

annulus pressure management for day to

day operations of SPDC wells.

To determine the existing issues of

annular pressure management and clear

procedures for improvement.

To check why EC- eWIMS interface is not

functioning and to fix it so as to increase

SPDC APM compliance from 3% to 90%.

DECEMBER 2012

DELIVERABLES

3



Master

RELEVANCE TO BUSINESS

Prevention of HSE incidents – achieving goal zero.

Avoiding production loss and costly remedial activities.

Upholding company reputation- continued license to operate.

DECEMBER 2012 4



Master

APM OVERVIEW APM is one of the key components of Well Integrity Management System.

Wells are made up of pressure vessels within other pressure vessels, there is therefore need to maintain these vessels within the operational limits.

Types of Annular Pressures

Thermal Pressure (TP)

● Caused by expansion / contraction of fluids in annuli due to changes in temperature.

DECEMBER 2012 5

Applied Pressure (AP)

Pressure applied on an annulus for various purposes e.g. Gaslift, Compensating for bullheadingSustained Casing Pressure (SCP)

● Pressure from réservoir, adjacent annulus etc.

● Must be investigated whenever pressure cannot be proven to be either AP or

TP.

●



Master

HOW AND WHY MONITOR ANNULAR PRESSURE?

Annulus pressure is compared to the Maximum Allowable Annulus Surface Pressure(MAASP) and the Maximum Allowable Well Operating Pressure(MAWOP).

Pressure ≥ MAWOP and MAASP Indicates Integrity Issue.

Pressure is monitored to avoid Well Failures and Loss of Containment.

DECEMBER 2012 6

CollapseBursts



Master

PROJECT METHODOLOGY

DECEMBER 2012 7

TASK 1

APPROACH

APPROACH

APPROACH

APPROACH

TASK 2

TASK 3

TASK 4

TASK 5

APPROACH



Master

SUMMARY OF KEY ISSUES OF APM IN SPDC

DECEMBER 2012 8

Issues Number of Wells

Frequency (%)

Contributors Sample

wellsWellhead Seals Failure

6 Oil wells 3 Tubing hanger seal leaks

OPUK- 26S

Tubing- Annulus Leak/Communication

I64 Gas wells

18 Oil wells91

Valve LeaksCorrosion holes in TubingCasing CorrosionThread leaks

FORC-121T

UGHE-25T

Cement Integrity Failure 12 Gas wells 6

Gas migration due to poor cement bond.

AFAM 24

Total 200 100

A total of 200 Wells investigated.

About 99% of Tubing-Annulus leaks occurs at Installed Valves in SPM.

About 90% of T-A leaks occur in gas wells.



Master

THE DATA MANAGEMENT APPROACH

DECEMBER 2012 9

Integrity management

Planning and scheduling

EXISTING APPROACH

EC Interface not functional PROPOSED APPROACH

Manual Update

Annulus Pressure

Integrity management

Planning and scheduling

Annulus pressure

Auto

mati

c U

pdate



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REASONS FOR NON-FUNCTIONALITY OF EC-EWIMS LINK

DECEMBER 2012 10Footer: Title may be placed here or disclaimer if required. May sit up to two lines in depth.

Unified Well Identifier(UWI) of most wells are absent in EC.

EC Connection details were not made available to the programmers that set up the link.

There was no access to EC production database.

Updated Pressure in EC were not entered in the right cell where eWIMS can capture the data correctly.



Master

APM COMPLIANCE MONITORING

DECEMBER 2012 11

Targ

etMONTH AVERAGE

COMPLIANCE(%)

July 2.8

August 3.8

September 4.8

October 6.1

November 5.0

Factors Contributing to VariationsSome wells are connected to the PI Interface.

Update of Operating Envelopes- MAASP & MAWOP in EDM

Manual update of annular pressures of some wells.



Master

CASE STUDY : FORC- 121T HIGH CHP

DECEMBER 2012 12

Annulus Pressure Build Up Analysis

High annular pressure of about 255 barg (3700 psig)

B annulus pressure exceeded MAASP

Continuous build up after bleed down

Equalization with THP.

Wellhead photo

Annulus Annulus pressure (psi)

MAASP (psi)

A 3700 4928

B 2100 386

Recorded Data



Master

FORC-121T : Casing and Cement Schematic

4640’, 13-3/8” Casing shoeTOC – 5000 ftah

TOC ~9150 ftah (from CBL)

10570ftah, 9-5/8” csg

13080ftah, 7” Casing Shoe

AB

Casing outlet

Casing outlet

H3.500 Reservoir perf (12708 – 12738 ftah)

Wellhead seals (potential leak paths)

1 ‘ DCKValve + Dumb kill valve failure suspected.

Tubing

DECEMBER 2012 13

HC Reservoirs btw 5250 – 6970 ftah with reservoir pressure range of1977 – 2500 psi



Master

DECEMBER 2012 14

Gas Rate of about 2.3MMScfFBHP of about 2600psig

PROSPER MODEL OF FORC-121T

Current Gas Rate of about 3.0 MMScfdMatched



Master

MODEL FOR ANNULUS PRESSURE BUILD UP ESTIMATION

DECEMBER 2012 15

AREAS OF INTEREST

Fluid Influx into the Annulus – Leaks

Change in Annulus Volume – Buckling

Effect of Flow rateP Annulus

Pressure3500.6 psi(approx)

A Coefficient of thermal expansion

0.467°F-1

V’ Annulus Volume 2080.6 ft³

V Volume of Fluid in Annulus

2080.6 ft³

K Coefficient of Isothermal compressibility

2.78 E-4 psi-1

ΔT Average change in Temperature

1.8°C

ΔV Change in Fluid Volume

80 ft³

ΔV’ Change in Annulus Volume

Negligible

P = I/K(AΔT-ΔV’/V’+ΔV/V)



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THE PLANNED MITIGATION STRATEGY

DECEMBER 2012 16

Continuous Pressure Build up

Down hole Restriction

Build up Continues



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OTHER MITIGATION STRATEGIES TO BE CONSIDERED

DECEMBER 2012 17

Vacuum Insulated Tubing.

Corrosion Resistant alloys

Shrinking Spacers – MMA.

Foamed Spacers- Nitrogen

Self plugging- gas condensate sealant

VIT MMA Spacers

Foamed Spacers



Master

SUMMARY OF FINDINGS

DECEMBER 2012 18

High annulus pressure in FOCY121T is due to failure of the installed valve at the SPM of the tubing.

EC-eWIMS Interface was not functional due to the fact that the UWI were not entered in EC and there was no connection details made available.

Annulus pressure build up in SPDC occurs most frequently in gas wells.

Most of the recorded cases of build up occur due to the valves installed in the tubing.

The estimated annulus pressure is about 3500.6 psi from the Model and close to measured value of 3700 psi.

Pressure build up in FORCY- 121T is facilitated by increase in production rate.



Master

CHALLENGES AND RESOLUTION

19

CHALLENGES ENCOUNTERED RESOLUTION

Delay in Data Gathering/ Limited Data

Sought data from many sources and followed up in a timely manner.

Time constraint and management Drew a work plan with expected time of completion of each task.Weekly reviews with supervisor.Engage in PT/WIMS/Programmer weekly meetings.

First experience in Petroleum Engineering.

Attended training sessions e.g. Well Integrity courses and field visits to facilitate learning. Personal studies via SOU and IPIMS.

Tight Schedule of Key Stakeholders Booked appointments and followed it up timely.

Limited access to annulus due to stiff valve and swampy location of FORC-121T.

Worked with the available data pending when there is access.Mindful of the hazards and safety rules.



Master

KEY STAKEHOLDERS

20

Mode of Communication

One-on-one meetings

Live meetings

Telephone calls

Emails

Microsoft Office Communicator (MOC)

Well Integrity Focal Point- Gabon, SNEPCO and SPDC.

Asset Production Technologists.

WRFM Leads.

Programmers- Global eWIMS and EC Custodians.

Production Operations Team.

Well Intervention Engineers

DECEMBER 2012



Master

LEARNING

Developed research skills.

Better understanding of the need for integration and team work .

Improved networking/ persuasive ability.

Improved HSSE awareness.

Better understanding of approach to tasks ahead so as to meet set targets.

Learnt to be courageous and resilient when faced with unfamiliar problems.

Better understanding of engineering as related to business.

Improved practical knowledge of well Integrity management.

Better understanding of the use of Production Technology tools e.g. IPM PROSPER. 21



Master

CONCLUSION/BROADER IMPLICATIONS

Efficient monitoring of pressure will ensure the safety of assets, people and environment.

Avoiding pressure build up that may cause catastrophic failures.

Reducing environmental degradation.

Reducing unscheduled shutdown and loss of containment.

Enhance compliance with statutory requirements.

Enhance company’s reputation.

Contributing to the Team’s KPI.

22DECEMBER 2012



Master

RECOMMENDATIONS

Gas wells should be completed with corrosion resistant alloys to avoid leaks.

There should be less accessories/ jewelleries Installed at the Tubing

to avoid creating leak paths e.g. DCK valve installed at the tubing of

FORC -121T is unnecessary.

There should be regular monitoring of annular pressure especially

during well start up to ensure timely Intervention and avoid sudden

failure.

There should be regular update of pressure data , this will ensure

timely intervention.

Further research should be carried out especially in the area of build

up prediction as this will serve as a check on the measured pressure.DECEMBER 2012 23

THANK YOU



Master

BACK UP SLIDES

April 18, 2023 25Footer: Title may be placed here or disclaimer if required. May sit up to two lines in depth.



Master

Risk Assessment of FOCY121T




Master

FOCY121T :WELL STATUS DIAGRAM


Tension(lbs) 20,000 LBS

Stab in force 5'

size of Drift.

Derrick Floor Elevation

Datum-Top C.H.H. 39.64

Datum-Top Tree 27.91

Spud in Date 9/27/1986

Init. Completion date 9/30/1989

Recompletion Date/S 6/16/1992

casing Data

7" casing 13080'

No. of Joints L/S 390 JTS

No. of Joints S/S 6 JTS

Fluid in Hole 13,000

S PDC WARRI PCW

FORCADOS YOKRI-121COMPLETION STATUS AS AT 15-06-92

AUTHOR PCW-PTC Date: 26-02-2002LAST REVIEW Date: SEPT. 1992ELECTRONIC VERSION Odigie, T.CHECKED Sign: Mafe, A. A.

SIZE GRADE LBS/ft TYPE No.J TS

3-1/2" 12.75 HCS

2-7/8" 6.5 HCS

ITEM TYPE SIZE PSI REMARKS

GATE VALVE 'FCC' 4-1/16" x 4-1/16" FL 5000 PSI INSTALLED

XMAS TREE 45 Y SSB 7-1/16" x 4-1/8" x 4-1/82 API 5000 PSI WP INSTALLED

ADAPTOR FLANGE

TUBING HANGER SRT 4-1/2" API 5000 PSI WP INSTALLED

TUBING HEAD SRT 11" x 7-1/16" 5000 PSI x 5000 PSI 4-1/2 RAMS

RISER SPOOL ADAPTOR/WF 13-5/8" x 11" 3000 PSI x 5000 PSI INSTALLED

C.H. HOUSING WF 13-5/8" x 13-5/8" CSG 3000 PSI WP INSTALLED

SEAL BUSHING 'X'

Leak at DCK + Dumb kill Valve



Master

April 18, 2023 44

SPDC Well Integrity Data Management Approach

FULL MEANINGS

TESTING AND

MAINTAINANCE RESULTS

AUTOMATIC UPDATE

MAINTENANCE

SCHEDULING

LOGIC LOOP

TAs

FSR - Facility Status Report

WFM – Well Failure Model

eWIMS- electronic Well Integrity

Management System.

EDM Open Wells – Electronic Data

Management

PI/EC – Production Information/Energy

Components

DCS- Distribution Control System

PRG- Pressure gauge

DCSPRG

RRECORDED CASING HEAD/

ANNULAR PRESSURES

Man

ual U

pd

ate

Au

tom

ati

c U

pd

ate

Automatic Update



Master

Annulus Investigation Process Flowchart


Record casing pressure (P)

|P - Pb| < 100 psi AND P < MAWOP

Pressure bleeds to ambient AND P builds to MAWOP in

longer than 1 month AND does not bled liquid HC

No

Yes

No

Yes

Perform risk evaluation

Risk acceptableIncrease monitoring frequency

No

Yes

Perform well remediation or risk reduction measures

Establish baseline pressure (Pb)

Perform pressure bleed down and analyze. Determine if there is

communication to the inside annulus.

2Leak during

start-up

1Start-up

complete

Communication with the inside annulus

No

Yes



Master

Poor Data Management


Urgent Intervention Required

Overdue

Soon to be Overdue

Up to date



Master

COST ANALYSIS

DECEMBER 2012 31

S/N JOB AMOUNT PER UNIT($)

QTY AMOUNT($)

1 Barge per day 15000.00 14 217000.00

2 Rescue Boat per day 6500.00 14 91000.00

3 Slick Line Unit 3000.00 14 42000.00

4 Wellhead Support 2000.00 4 8000.00

5 31/2 inch SCSSV+Lock Mandrels+plug(2pcs)

53000.00 1 53000.00

6 Logistics/Security/Escort

1200.00 15 18000.00

7 Fuel 1200.00 14 16800.00

8 Work over 6500000.00 1 6500000.00

8 Total 6582400.00 6945800.00

TOTAL ESTIMATED COST = $6945800.00



Master

PROJECT PLAN

April 18, 2023 32

ASSESSED INTERNSHIP PROJECT TOR

PROJECT TITLE

ANNULAR PRESSURE MANAGEMENT

IN SPDC INTERN:Ofoedu Andrew

SUPERVISOR:Cosmas NwankwoMENTOR:Nwadike Nkili

DURATION:Aug 1 - Nov

ACTIVITY AUG. 1-3 AUG. 4 AUG 5-7 AUG 8-

12 AUG.

13AUG.

14AUG. 15-

20AUG.

21AUG 21-

31 SEPT 1-30

OCT 2-4

OCT 5-12

OCT 13-14 NOV/DEC

Literature Review

SPE/OnePetro, SOU, IPIMS Webite Search for Related Information

EP Well Integrity Management Manual(WIMM)

Internship Terms of Reference (TOR)

Training & Data Gathering

Understand Well Integrity Management System and Its Relevance

Training on The Determination of Annular Pressure Data(MAASP,MinAP,MAWOP)

Training on the Use of eWIMS and Interface with other Data Management Tools(EDM,FSR, EC)

Obtain MAASP Data from Selected Wells

Visit to Fields & Review of Annular Pressure From Wells of Interest

Sellect Wells For Detailed Assessment

Process Improvement in Standard Operating Procedures(SOP)

Mid Term Review

eWIMS- EC Link Testing

MAASP UPDATE IN EDM and eWIMS

Prepare Outline/Draft of Report

Preparation of Report/ Presentation

Review Report and Include Modifications

Project Presentation

internship project presentation

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applied pressure ap

casing pressure scp

pressure mawop

monitor annular pressure

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