First Heavy Workover on Intelligent Completion in Santos Basin Pre-Salt
Authors: Pereira R. H. , Cisneiros C. , Schnitzler E. , Sales I. M. , Armani N. J. , Almeida R. L. , Roman R. , Rosa R. S. , Ascaneo W. M. 
Published: March 2024

The intelligent completion installed in several Brazilian Pre-salt wells present some challenges to workover. Most wells are equipped with integral intelligent completion and all of them presented severe fluid losses after acid stimulation. This paper will describe the main challenges and new methods used to perform a workover in such a scenario, including several through tubing operations performed such as nippleless plug set between production zones, feedthrough packer release and the mechanical cutting of the production string.

The usual methods to remove the intelligent completion string require to control fluid losses to the reservoir or to install a mechanical barrier to isolate the reservoir. The team evaluated that both options had high risk of not delivering the expected results. The proposal was to remove the completion string in a single trip, sustaining losses. The reservoir would be in communication with the riser while pulling the completion string, so well safety concerns were considered. Several wireline and electrical line operations were conducted to isolate lower zone, cut the production string, unset de packer, and deal safely with fluid losses.

To use Managed Pressure Drilling (MPD) techniques in workovers, several tools had to be modified. Traditional tubing hanger running tools with control lines wouldn’t be compatible with sealing in the rotary control device and the emergency mechanical retrieving tool didn’t provide through tubing access, so a purely mechanical tool had to be developed with both features.

Several through tubing operations must be performed before releasing the tubing hanger and packer and have been detailed in multiple risk analysis and workover on paper. The well barrier configuration for the string removal has been extensively discussed. The conservative solution of using two additional barriers inside the tubing was adopted for this first job. Contingencies in case of failure to unset the packer were detailed. Additionally, it was necessary to present contingencies in the advent of getting stuck. The technique has been successfully applied to one workover in 2023. Only the upper zone had to be recompleted after the workover, so it became a less challenging candidate for this trial. The well presented total fluid losses due to acid stimulation, thus the tubing was removed using Floating Mud Cap technique. All the main operations were successful, and the intervention goal was safely achieved below the expected budget.

This paper presents the first use of MPD techniques for heavy workover combined with modern electric line tools in high complexity and high productivity wells. This technique proved to be suitable for this scenario. It simplifies several challenges of common workovers, but also adds new risks that must be carefully evaluated. It’s a game changer in workover techniques in high water depths, such as the Brazilian Presalt, and the whole industry might benefit from it.