De-Risking Downhole Disconnection Tools for Open Hole Intelligent Completion in Deepwater Wells

Abstract

Abstract This paper presents how Petrobras, in collaboration with suppliers and other operators, proceeded with a qualification and deployment plan for one of the new technologies recently introduced in its pre-salt wells. It covers the new downhole disconnection tools for control lines used in intelligent completion systems deployed in open hole, also known as WDT – Wet Disconnect Tool. Downhole disconnection systems allow connecting and disconnecting the tubing and control lines, hydraulic and electric, between the upper and lower completion. This equipment is frequently used when the ICVs are deployed in open hole, as applied in the latest pre-salt projects in Brazil. However, a successful performance of these tools may be severely impacted by downhole conditions and the intrinsic challenges in deepwater wells. High mechanical loads, pressure and temperature variations, aggressive wellbore fluids and the presence of debris are just some of the concerns. Therefore, the operator has set a robust qualification plan to de-risk the introduction of this technology in its offshore fields. In strong collaboration with the suppliers, the possible weak points and risks were identified and addressed in the qualification plan. This development was also guided by reliability targets for the final systems, based on reliability tests at component, sub-system and system levels. One of the main concerns was to establish a successful connection in the well between the two parts of the tool. Despite all the efforts to clean the wells before completion deployment, the presence of debris is always a risk, and some debris tolerance need to be considered. A representative mixture of debris was defined for the connection and disconnection tests, mimicking wells conditions as much as possible. The overall development and qualification of the tools was successfully finished, after several changes in the original designs. In the end, the tools showed good debris tolerance and positive expectations in terms of the performance in downhole conditions. The trial wells, where the tools were deployed already connected (single trip), faced no issues related to the new tool. Dual trip installations are expected to happen shortly. The innovative use of downhole disconnect tools in deepwater wells opens several opportunities for projects that benefit from the use of intelligent completion. Improving these tools robustness and reliability helps building the necessary confidence for this kind of application. Future opportunities of incorporating downhole fiber optics sensing in the lower completion and electrically actuated valves also benefit from this experience.