First Oil Requirements Drive Simultaneous Drilling and Subsea Construction Operations on UK Central North Sea Development

Abstract

Abstract Accelerated production targets in the field development plan of this United Kingdom Continental Shelf (UKCS) project drove the requirement for design and drilling of four production and two injection wells with concurrent subsea construction and planned production start up. The paper's objective is to demonstrate that the use of a jack up with subsea template and high pressure riser is a worthwhile subsea well development method. The individual technical solutions brought together during the well construction process are described with reasons for their selection. The Performance Improvement Process that was developed and used to allow continuous improvement and facilitate change both on and offshore is reviewed. The paper focusses on well construction and will not consider the specific detail of the project's subsea infrastructure and production units. The project brought together the following technical elements to deliver a successful campaign: Mobile Offshore Drilling Unit operations with modifications to allow tree running from deck, high pressure riser design and analysis, subsea wellhead operations, modifications to existing subsea trees, use of Riserless Mud Recovery system during batch drilling operations, template design and reservoir steering technologies. Results are that activities improved from well to well with little impact on subsea construction and this can be demonstrated by performance data. The conclusions are that jack up operational efficiency was achieved on the subsea development and delivered cost effective well construction during simultaneous operations. A change in operational mindset can be achieved to allow subsea activities and equipment to be run from a jack up unit. Rigorous application of a Performance Improvement Process can enable change and help to manage project complexity. The activities described in the paper can be applied to marginal developments where accelerated production is a driver or rig market constraints are a factor during rig type selection.