Integrated Approach Enabled Successful Delivery of the Longest Well on Odoptu-More Field for Russian National Oil Company

Abstract

This paper provides the results of the application of integrated approach to drill the longest extended reach well which has ever been drilled in Odoptu-more field (North Dome) in Sakhalin. Although many extended reach drilling (ERD) wells have been already drilled by the operator in Odoptu-more field, extreme reach wells always require new solutions. Reaching remote reservoirs by applying standard well design of Odoptu-more field was not possible due to high standpipe pressure (SPP) and equivalent circulating density (ECD) in 8 ½-in production section. Engineering study resulted in partial upsize of a well design and change 9 5/8-in casing to liner followed by remaining challenges: 9 5/8-in liner could not be delivered to required depth due to string buckling. Several key technical solutions were implemented in the project thus allowing to deliver the longest well accident-free. Those solutions included well design modification allowing to drill 8 ½-in production section to reach remote reservoirs and 9 5/8-in liner delivery to the required depth using "mud over air" flotation technique for the first time in the project. Having applied integrated approach, the project team broke a new record in drilling the longest well at Odoptu-more field with total measured depth 8699m, ERD ratio 4.89 and Directional Difficulty Index (DDI) of 7.6 (Alistair W. Oag 2000). Drilling extreme reach ERD well unlocked opportunities for the operator to reach and put into the production more distant offshore oil-bearing reservoirs from the land rig without changing existing pad facilities.