Decision Risk Management Review of Through-Tubing Drilling Uptake on UKCS

Decision Risk Management Review of Through-Tubing Drilling Uptake on UKCS C. Cranfield (DTI), L. Wickens (AEAT), G. Maitland (LEA)

Background Objectives Workshops Format Results Conclusions Recommendations Follow-up Outline

OGITF in Sept. 1999 reported CTD and TTRD potentially important currently available not widely used on UKCS could significantly raise recovery However, in early-2000 Lack of CTD and TTRD activity Why? DTI initiated a review to find out Background

Onshore (UB) Offshore No. of recent UK CTD wells, to mid-2000 • Widely used on-land; Alaska, Oman • Few UKCS CTD wells • More TTRD wells in 2000

Review situations in which TTD is viable on UKCS Understand decision-making factors Disseminate best-practices Raise awareness Hopefully stimulate TTD activity Specialists: L. Wickens, AEA and G. Maitland, LEA Objectives

Met with five operating companies February - July 2000 Two majors with previous UKCS TTD experience Three intermediates Structured for open debate Drilling objectives network Mind map Ranking exercise CTD vs. TTRD Specific field situations Format of Workshops

Improve NPV Accelerate production Reduce costs Increase reserves Drilling objectives network

Improve NPV Accelerate production Reduce costs Increase reserves Drill new wells Less downtime Conventional sidetrack Faster drilling Drilling objectives network

Improve NPV Accelerate production Reduce costs Increase reserves Drill new wells Less downtime Conventional sidetrack TTD Faster drilling CTD TTRD Less formation damage Underbalanced Drilling objectives network

WHY IMPACT Lower day-rate Prolong field life <1mmstb targets Depleted reservoirs 3rd party satellites SNS Good pre-planning Unswept reserves Dedicated crews ECONOMICS Multiple wells WHEN Cost uncertainty Bigger cranes Needs to be cheaper Manpower resources CTD Sufficient confidence ALTERNATIVES Enough wells Conv. sidetrack Casing drilling TTRD Hybrid rigs WHERE WHAT’S NEEDED SNS Lighter coil Idle rig Enabling technologies Concurrent ops Common alignment Buy-in from management Mind map

Drilling performance / Capex Pressure transitions, UB Pressure transitions, OB Technical maturity HSE Well productivity Lead time (topsides, wells) Upfront Capex Lithology selection Ranking Results - CTD vs. TTRD • Attributes from mind map were ranked and weighted • Neither option strongly favoured • Depends on opportunities • TTRD wells planned for 2000 and 2001 • Companies will monitor next 2-3 years

Company 1 Company 3 Company 4 -80% -60% -40% -20% 0% 20% 40% 60% 80% CTD Favoured TTRD Favoured Balance of Forces

Past TTD experiences • Lack of success • Stuck-pipe / hole collapse • Swelling shales • Cost over-runs • Lack of continuity between jobs • Equipment not fit-for-purpose • Obstacles • Insufficient crane capabilities • Effect of low SNS pressures on cuttings transport • Lack of well candidates • Lack of SNS specialist vessel • CTD problems provided learning opportunity

Light-weight coil Composite re-usable Titanium high-strength Reliable BHA’s Precise and reliable window-cutting Whip-stock Software Could accelerate uptake of CTD and TTRD on UKCS Current developments

Companies and service / technology providers: Joint-industry campaigns Collaborate on CTD technology, logistics, equipment Peer reviews, sharing of information Risk-reward arrangements Funding for R&D, specialist training DTI: Address negative perceptions of regulatory approval process Advocate collaboration in SNS, to develop specialist vessel Quantify benefits of UBD on UKCS Recommendations

Need for Specialist Vessel • UBD is required to drill low-pressure SNS formations • SNS platforms do not have • Drilling rig • Pumping / fluid handling capacity • Accommodation / space • Solution would be mobile unit • Operate alongside platform • Move between operators • Mobile unit also valuable for CNS / NNS • Targeting small reservoirs, that deplete rapidly • Providing concurrent drilling for platforms with own rigs

CTD and TTRD considered potentially important, low cost Need to overcome associated difficulties Lack of continuous, integrated programmes Crane capacity, rig space Risk to mother-bore Up-front costs Lack of confidence Step-out distances, equipment, expertise Perceptions Aim to reduce CTD side-track from > £ 2.2 mm to < £ 1.0 mm Encouraging 2H 2000 results Under-balanced CTD of particular interest in SNS Conclusions

Workshops effective in sharing information ITF projects ongoing DTI Continual promotion and support of improved recovery PILOT initiative on undeveloped discoveries Participation in ITF coiled tubing UBD JIP Suggestions on regulatory approval process to: colin.cranfield@dti.gsi.gov.uk 01224 254066 Follow-up

Decision Risk Management Review of Through-Tubing Drilling Uptake on UKCS