brent abandonment campaign

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Brent Abandonment Campaign P&A Technology - Section Milling Experience In Conjunction with Schlumberger

PAF Seminar - Stavanger 19th October 2016, 14:20-14:40

Martin Dow Wells Engineer - Brent Abandonment Design

1 October 2016

Brent Charlie and Cormorant Alpha – Stavanger 1978


Agenda

Introduction to Brent Field P&A Scope and Field Isolation Strategy

Overview of Field Isolation Strategy and Section Milling Requirements

Section Milling Performance to Date

Key Performance Focuses

Section Milling – What’s Next/Alternatives

Close-Out Summary

Q&A

October 2016 2


Brent P&A Overview – Project Scale Field Abandonment Philosophy

Introduction

1 October 2016 3


Brent P&A Campaign Scale and Challenges

October 2016 4

154 well slots -141 wells to abandon with 240 sidetracks to consider

4 Platforms (Brent Delta awaiting topside removal)

Currently executing operations on Brent Bravo - Alpha P&A start-up Q3 2016 and Charlie Q1 2017

Completed P&A on 73 wells

Variation of well architecture, well design, current integrity and usage

Previous abandonments of sidetracks and motherbore

Condition of 40yr old wellbore components

Historical data quality

No one fits all solution, each well requires tailored approach


Revised Brent P&A Philosophy - Section Milling Requirements

October 2016 5

Recent revised Field isolation strategy post OGUK guideline revision

Challenge made possible through in-depth monitoring study of

annuli pressures and zones with flow potential

Saving ~6,000ft total of shallow section milled windows

Potential for 2 milled windows per well

Up to 200ft window required depending on existing annular

isolation

Routinely mill 100ft windows with up to 150ft milled in a single trip

10 wells with dual section milling/dual casing isolations required

Currently executing first PWC operation/trial to reduce exposure

over dual isolation wells

Continual drive to improve milling performance through equipment

optimisations, personnel competency, swarf handling, procedures etc.

FormationTop

D C B A A B C D

Sea

Bottom

Utsira Shale 4Utsira Sst 3


Utsira Shale 1

As-is

Top Reservoir

Kimmeridge Clay

Shetland

Maureen Fmn

Lista Fmn

Utsira Shale 2

Utsira Sst 4

Shetland Plug 800ft

Horda Plug 800ft

Utsira Plug 800ft

Balder Fmn

Horda Fmn(Shale)

Horda FmnFrigg Sst

Lark Fmn Skade Sst

Utsira Sst 1

FormationTop

D C C D

Sea

Bottom



Utsira Shale 1

Balder Abandonment / Final Status

ISW

Utsira Sst 4

Utsira Shale 2

Utsira Sst 1

Lark Fmn Skade Sst

Horda FmnFrigg Sst

Horda Fmn(Shale) Horda Plug 800ft

Balder Fmn

ISW / Milling FluidLista Fmn

Maureen Fmn

Shetland

Shetland Plug 800ft

Top Reservoir

Kimmeridge Clay

ISW


Beginning of Campaign vs Now Where Have we Made Improvements

Section Milling to Date

2 October 2016 6


Bridge Plug on Mill 1.5days

Enhanced Knife Design

0.5days

Operator Competence

and Procedures

0.5days

Improved Swarf

Handling 0.5day

Optimised Fluid

Strategy 1day

Combined Mill and

Underreamer 1.5days

Combined Cement Plugs

2days

Section Milling Performance / Barrier Execution to Date

October 2016 7

Time to mill window and set abandonment cement plugs dramatically reduced from beginning of Brent P&A

campaign

From casing cut to tag of cement plugs 12days 2011 to <4.5days 2016

How Were These Improvements Realised?

*Based on deep milled window (reservoir isolation barriers)


Evolution & Optimisation of Remediation BHA Knife Technology – Insert Shape, Material, Cutting Characteristics Fluids & Swarf Handling Operator Competence & Consistency

Performance Improvements

3 October 2016 8


Separate Section Mill and

Underreamer

1 Trip Saved

Combined Section Mill/Underreamer

1 Trip Saved

Bridge Plug Run on SM/UR Assembly

Evolution & Optimisation of Remediation BHA

October 2016 9

Trip saving technology cut 3 round trips to a single trip remediation system

Have driven continuous performance with Schlumberger throughout campaign,

successfully introducing world first technologies into the P&A environment

Optimised BHA design for best milling parameters

Using collars in place of HWDP to increase stability and string inertia

Slick as possible BHA to mitigate swarf pack-offs

Inherent risk to milling performance where poor or no annulus seal exists

Mill life severely degraded, poor swarf characteristics, hole cleaning etc.

No solution to excessive casing movement – SM not prime option


Knife Technology – Insert Shape, Material, Cutting Characteristics

October 2016 10

Improved consistency in manufacturing and brazing process

Optimised fluid properties for enhanced swarf recovery

Titanium coating applied to knives

Completed trials of new knives with revised cutting structure

Achieved ROP of 4.5ft/hr vs existing target of 3ft/hr

Knives only 20-35% worn over 150ft window – Original window was planned to be 200ft with confidence this

could be achieved in a single trip

Improved consistency of swarf characteristics throughout window – Small Chips vs Long Coils

22ft Milled – Delaminated Cutting Structure 36ft Milled – Deviated Wear Profile 96ft Milled – Even Wear Profile 150ft Milled – 20-35% Worn


Fluids & Swarf Handling

October 2016 11

Basic generic milling fluids system – viscous/weighted sea water based milling fluid

Optimised for easy bulk building, maintenance, environmental impact and cost

No inhibitor added to mitigate formation/shale collapse

Field specific offset data and learnings important to fluid design

For swarf recovery alone viscous water enough - trade off with formation stability

High performance fluid system considered, but cost vs reward not advantageous

Milling performance/ROP restricted by surface swarf handling capacity

Also important to consider deck space footprint, deck loading, flowline position,

campaign length, additional POB, compatibility with existing drilling package/fluid

systems and position of secondary recovery magnets.


Operator Competence & Consistency

October 2016 12

Fishing & Remedial crew consistency has been critical to maintaining

milling performance throughout campaign

Drill crew personnel stability also key to sustaining performance and

driving continual improvements

Swarf Unit operator in constant communication with drill floor relaying

trends in swarf return and signs of pack-offs, fluid spillages, mill

performance etc.

Further Optimisation Opportunities:

Crew multiskilling to reduce exposure to high service company

demand and POB restraints

Surface pack-off monitoring system


What’s Next for Section Milling & Alternative Methods Summary Q&A

Section Milling Alternatives and Close-Out

4 October 2016 13


What’s Next for Section Milling and Alternatives

October 2016 14

Further trials planned using alternative knife design/insert material

Additional trials with DSM assemblies in collaboration with various service companies

Alternative Methods

Focus now on improving and verifying alternative, more efficient and cost effective isolation

methods to lessen reliance on section milling:

Through tubing cementing

Perf & test/verify – How much is enough? Challenging need for remediation.

Perf & wash cement – How to ensure right first time approach…

Dual string logging

Thermite plugs


Close - Out Summary

October 2016 15

Trip saving technology dramatically reduced barrier execution time,

target times increasingly more aggressive

Refreshed, performance focused approach to Brent P&A campaign

Personnel competency drives bottom-line performance. Standard

operation carried out multiple times every month keeps focus and enables

continuous improvement

New contractual incentives designed to drive technology improvements

Enhanced focus on alternative techniques and verification of isolation


Questions and Answers

October 2016 16

More Info : [email protected]

brent abandonment campaign

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