ADCO and NDC launched its Well Delivery Limit (WDL) initiative in May 2000 to deliver the step change in performance required to meet its business objectives of increasing production capacity and containing technical costs. In partnership with Shell's Drilling The Limit* philosophy, WDL's performance management system challenges the true value of ADCO's well delivery operations, as opposed to simply doing the same things in a faster and cheaper way. Two years into the initiative, WDL has been implemented on all ADCO rigs with great success and new ways of working have been created by breaking down the barriers between departments in addition to those between ADCO and its Contractors.

From an operational perspective, ADCO has reduced well construction time by more than 30% and reduced cost by 8%. In addition to this, substantial improvements in well quality and HSE performance have been achieved, demonstrating the positive impact that WDL has made on ADCO's entire business.

The successes to date have essentially been in the form of time and cost savings, but even more can be gained by applying of the process to the entire well lifecycle. In other words, now that ADCO have learned how to "drill the well right", focus has shifted to the higher-level objective of "drilling the right well right". This next step has already been implemented on new development projects where existing practices have been challenged to ensure that the overall field development objectives are met in an optimal manner.


ADCO currently operates twelve rigs for drilling exploration and development wells and three rigs for maintenance and reentry operations. Nearly 700,000 feet of new wells were drilled during the year 2000, and over 1 million feet drilled in 2001. ADCO's varied assets require a widespread approach to reduce unit technical cost, increase production and reduce operating expenditure. This has been successfully achieved by implementing the WDL process.

This paper reviews the experience gained from 2 years' worth of implementing the WDL process, by describing the results achieved and explaining the factors that were key to its success.

The Well Delivery Limit Process

Based on Shell's Drilling The Limit* process, ADCO introduced the Well Delivery Limit (WDL) to focus all stakeholders on delivering high value wells with significantly reduced unit costs andwithout compromising Safety, the Environment or well Quality. The planning and execution steps of the WDL process are presented in Figure 1.

The WDL process can be summarised as assuming the perfect well can be drilled and planning to do it, as opposed to marginally improving current practices. WDL is an integrated and comprehensive system that includes:

  1. New ways of setting targets

  2. A detailed, systematic and multi-disciplinary approach to well planning and construction.

  3. A structured approach for capturing and managing knowledge from all parties, at all hierarchical levels.

  4. A culture of openness, no blame and co-operation.

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