Intelligent completions and electrical submersible pumps (ESPs) are realizing greater oilfield acceptance because of their capabilities to improve recoveries, especially in multi-zone wells where production can be controlled and optimized without intervention. Previously, when ESPs had to be removed for routine maintenance, the whole completion had to be pulled, which would require significant time, risk, and cost. Now, an electrical disconnect tool exists that enables ESPs to be changed out without requiring the lower intelligent completion to be removed. This paper discusses the equipment and methodology recently used in a trial test offshore Brazil to reliably disconnect an ESP in the upper completion from the lower intelligent completion that had two interval-control valves (ICVs) and two dual-sensor pressure/temperature gauges. The trial test required the disconnect sub to be disconnected from the receptacle, then reconnected again, followed by an ICV and gauge function test to prove the reliability of the wet mate connector in the electro-hydraulic disconnect tool. This paper highlights the successful case history of the new disconnect tool installed in January 2013 in the Carapeba field, offshore Brazil. The paper will discuss the technical aspects of the concept, the well-planning details, completion procedures, installation lessons learned, and tool design improvements that will be adopted for use in future wells. This installation will initiate the use of electrical disconnect tools for upcoming intelligent completions involving ESPs, sub-surface safety valves, or long horizontal sections that may require the lower completion to be installed on drill pipe.

On January 15th, 2013, the first installation and operation (disconnect and reconnect) of a 3-½-in. electro-hydraulic disconnect tool (EHDT) was successfully completed with an intelligent completion. The completion was installed in the Carapeba oil field in Campos Basin, allowing the operators to manage simultaneous production of two distinct and isolated zones by remotely monitoring and controlling flow to each individual zone. (Fig. 1) This tool allows the secure and reliable disconnect and reconnect of the upper completion from the lower while maintaining electrical and hydraulic control line integrity. (Fig. 2) Thus, it becomes possible to change any part of the upper completion such a non-functioning safety valves, electrical submersible pump (ESP), or other component without recovering the lower completion. In addition to the time saved on well interventions, this operational flexibility provides a significant increase in operational safety, since it allows the complete isolation of the reservoir simply by closing the interval control valves (ICVs). Remotely-controlled ICVs can also be used to prevent fluid loss and possible formation damage during well interventions. This development aims to overcome the challenges of well interventions with wellbore equipment fixed at both ends (e.g. tubing hanger and production packer), as currently constructed in the pre-salt. The completion design for the Pre-Salt development in Santos Basin requires a 4-½-in. electro-hydraulic disconnect tool to simplify and increase the efficiency of critical interventions in wells with intelligent completions. It is essential to emphasize that the learning acquired in this intermediate stage with the 3-½-in. tool on the Carapeba field, will be essential to guide the continued development and qualification of the 4-½-in. tool that is currently being developed to be used in pre-salt areas. Introduction Intelligent completion (IC) provides the ability to monitor multiple zones of a reservoir or between intervals with large difference in permeability within the reservoir of interest, through the real-time measurement of temperature and pressure values ??and to selectively and remotely control opening and closing of the reservoir sections. This functionality allows reservoir engineering better management of production which is essential for reservoirs with high geological uncertainty as heterogeneous carbonates found in the pre-salt. However, the use of intelligent completion technology inherently creates additional difficulties for well interventions due to the need for removing the entire lower completion string (equipment below EHDT - production packer, valves, and gauges) which can result in high operational risks. This completion configuration would require a high risk intervention combating fluid loss in each zone with the risk of solid deposition (e.g. calcite) over the lower packer, unsetting packers, and pulling the lower completion string out of the hole. Aiming to overcome the challenges in this scenario, a project was created to develop a tool capable of disconnecting and reconnecting safely and reliably the upper completion from the lower, while maintaining the electrical and hydraulic control line integrity, yet allowing a simpler and safer intervention.

Adequate fluid placement and complete zonal coverage during a matrix acid stimulation is critical to the success of a treatment. The use of distributed temperature sensing (DTS) is a relatively new technique that can be used for monitoring downhole fluid placement during a treatment. It uses a fiber-optic distributed-temperature-monitoring system to provide continuous temperature profiles throughout the entire length of the well, giving relevant information to perform qualitative and, in some cases, quantitative analysis of fluid placement downhole. This paper describes the design and construction of a laboratory scale flow-loop apparatus to demonstrate the application of DTS technology for downhole fluid placement monitoring. The apparatus constructed contains three inlet and exiting points to simulate well perforations, a method to raise or lower fluid temperature and thus introduce temperature spikes or tracers, and optical fiber and sensing equipment and instrumentation to measure and compare measured and calculated rate data. The system is capable of simulating several well flow conditions, such as fluid injection, fluid production and crossflow. The designed apparatus has proven to be versatile, compact, and useful for understanding and training professionals regarding how DTS technology can be used for monitoring downhole fluid flow and placement.