Case History of the World's First Installation of Continuous Chemical Treatment in a Horizontal Openhole Gravel Pack to Inhibit Scaling While Maintaining Production Levels

Abstract

Offshore deepwater fields usually require a semisubmersible rig to drill and complete their wells. Additionally, if any intervention is required in the well, a costly workover rig will need to be moved to the site. Hence, solving problems remotely using a method requiring less intervention can provide substantial savings in the overall cost of the well. Such an opportunity emerged when working on a project in the offshore oilfields of Brazil, where use of water injection as a reservoir energy maintenance method is common. However, the mixture of water injection wells and oil producing wells can lead to the formation of barium sulfate on downhole equipment, which can precipitate under pressure change during production. Barium sulfate's insolubility makes its removal difficult; usually requiring the use of special tools for mechanically cleaning the gravel pack screens’ interior. This type of intervention method requires an offshore rig. It demands a considerable amount of time and resources to complete the cleanup procedure, especially in the case of long openhole horizontal gravel packs. However, by pumping inhibitors directly to the gravel pack screens’ interior, production suspension is avoided, along with any intervention-related time and cost. This paper will describe the world's first installation of a horizontal openhole gravel pack system specifically designed to allow continuous pumping of scale inhibitors. The chemicals were injected through a single flowline down to the interior of the sand-control screens at two distinct parts of the well pay zone, without interrupting oil production in offshore Brazil. This pay zone management system incorporates a hydraulic wet connector, an openhole zonal isolation packer, and two chemical injection mandrels with flow regulator valves. The mandrel valves evenly distribute the barium sulfate inhibitor, preventing its deposit inside the screen. Potential applications of this system in offshore Brazil are being considered on the basis of this successful first installation. Results of this project, as well as other compelling data, suggest that operators may benefit from its incorporation in their field development plan, maximizing their return on investment.