OIL & GAS Well Integrity and QRA of the shut-in wells or .... Identify the well attributes and well...

DNV GL © 2014 26 October 2015 SAFER, SMARTER, GREENER DNV GL © 2014

26 October 2015 Tobias V. Alvarenga

OIL & GAS

Well Integrity and QRA of the shut-in wells or wells producing with degraded barrier

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– how to optimize your decisions

DNV GL © 2014 26 October 2015

Outline

Introduction Late Life

Wells

Well Integrity and

QRA Methodology

Case Study

Remarks

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Introduction

DNV GL © 2014 26 October 2015 4

Macondo – A Game Changer

“Leaders – CEOs, COOs, presidents and senior VPs – of drilling contractors, operators and service companies are taking an active interest in the Well Control Institute”

-Moe Plaisance

New EU Offshore Safety Directive introduced to bring “North Sea” best practices into force across Europe


Well Integrity

NORSOK STANDARD D-010 ”Well Integrity in drilling and well operations” (2013)

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Well Integrity is the application of technical, operational and organizational solutions to reduce risk of uncontrolled release of formation fluids throughout the life cycle of a well


Challenges – Late Life Well Integrity

1. Difficult to assess the well integrity status – Loss/lack of instrumentation

– Different operating conditions

– Lack of information

2. Risks and uncertainties related to the well integrity during a workover / well intervention operations

3. Limited economic return on investment for a workover / well intervention operation

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Well Integrity and QRA Methodology


Step 1 – Assess the Well Integrity Status

Identify Well Barriers – current status of the well

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Identify Leak-paths and Failure Scenarios

Node: 12

Date: 7/3/2013

Function: To maintain the required back pressure during the operation of RGH system

IDFUNCTION FAILURE MODE

FAILURE

MECHANISM

SYSTEM FAILURE

EFFECT

FAILURE DETECTION /

SAFEGUARD

Cons

eque

nce

Like

lihoo

d

Criti

calit

y

COMMENTSACTION

ITEMS

1PT201, 202

To provide input

to M1 and M2

PCV valves and

required back

pressure during

RGH operation

(300psi)

incorrect reading diaphragm seal rupture

Needs to be a logic to

manage different sets of

readings from PT201 and 202

System:

Sub System:


Step 2 – Conduct a Risk Assessment

Consequence Analysis

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Reliability models

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Dispersion and consequence modelling


Step 3 – Decision Making and Economic Evaluation

Better basis for decision making

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Case Study


Well Integrity and QRA Working Flow

1. Assess and Group the wells according to their well type, operational status and architecture;

2. Creating well barrier schematics for each group of wells;

3. Identify the well attributes and well barrier elements which influence the level of risk;

4. Workshop on well groupings and well barrier schematics;

5. Perform a Fault Tree Analysis for Likelihood Assessment, quantify the likelihood a leak/release

6. Performing Consequence Analysis for all the wells, assess the consequence related to a leak/release

7. Evaluate the economic consequence related to the leak/release scenario

8. Present the findings and conclusions from the QRA in risk matrix

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Prioritizing Well Intervention Operations

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Overview:

Wellhead platform with 9 wells in operation

Workover and well intervention operations are performed with a jack-up rig

Well Integrity issues related to leakage in tubing and casing hangers in several of the wells

Focus on potential hydrocarbon release and blowout

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Current Available Assessment:


Results and Conclusions

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As a result of the study, the wells were grouped into:

Close-in and plan workover operation

Continue production and plan workover operation

No intervention or workvoer required (additional risk mitigation measures)


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Remarks


“What would come next?”

How long current “acceptable” risk last for?

– Some damage mechanisms are time driven

– Some well characteristics can change overtime

– Are all wells monitored?

– How would risks evolve in the next 10 years?

– Zero leakage or “zero” environment harm?

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Risk

Time

Acceptable Risk Level

Residual Risk

Workover too late Taking too much Risk

Long term Workover Plan


Risk

Time


Residual Risk

Anticipated Workover Excessive Costs



Risk

Time


Residual Risk

Cost Efficient Workover



Managing Well Integrity

A well integrity assessment provides a systematic review and evaluation of the status of the well Need to address not just…

– The technical barriers – The operational barriers But also…

– The organisational barriers Nevertheless, by quantifying risks you

have a better basis for comparing and prioritizing your decisions

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SAFER, SMARTER, GREENER

www.dnvgl.com

Thank you for your attention!

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Tobias V. Alvarenga [email protected] +55 21 3722 7260

OIL & GAS Well Integrity and QRA of the shut-in wells or .... Identify the well attributes and well...

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