Abstract
Since Brazil produced first oil from the Campos Basin (offshore) in 1977, several companies have tried to reduce costs and speed up their offshore interventions. This requirement is even more necessary as the fields mature with limited oil production.
The operator's objective has always been to avoid interventions or increase the time between them for the duration of the wells’ life. When required, the normal way to perform these interventions has been by using heavy workover rigs, but during the last five years, this process has changed since Brazil started to perform these activities using Light Well Intervention Vessels (LWIV). These vessels allow a different approach to traditional methods of thru-tubing interventions while still meeting the requirements of local regulations.
This paper describes recent thru-tubing techniques used in a mature field during a large P&A campaign. It shows the high potential synergy integrating a LWIV with Coiled Tubing (CT), Slickline (SL), Wireline (WL), and cementing technologies for use in Brazilian activities.
CT equipment rigged up as the primary and selective intervention on a LWIV offers more flexibility between service lines, reducing time with safety and quality. This integrated solution applies since the most recent Electric (e-CT) technologies added to conventional tools, such as inflatable packers, slickline plugs, tubing punches, logging devices, and others, creates new procedures and capabilities to speed up the well intervention operation. Some jobs previously performed in over 45 days, can now be carried out in less than 13 days.
Comparing this new offshore P&A thru-tubing technique with traditional heavy well workover interventions results in a significant reduction in Abandonment Expenditure (ABEX) when operations are performed through the production tubing, allowing the completion tubing to be left in the well.
The method described in this paper, backed up with a detailed case study, illustrates the significant parts of the process, from cement placement preparation and slurry specifications to pumping through the CT into the wellbore and the cost reduction gained. Conclusions and recommendations offer more technical references for further similar applications.
