The FPSO P-58 is located in a deepwater field and produces pre and post salt reservoirs. The artificial lift method selected for two post salt wells is the mudline ESP, where the equipment is installed in a submarine skid. The main advantage of this technology is to reduce intervention costs due to cheaper vessels. The concept was developed and tested in two Petrobras projects: Espadarte and Cascade-Chinook fields.Some of the challenges are related to the need for horizontal positioning of the equipment, due to the dimensions involved. This impacted the method of assembly and installation of the ESP in the capsule, as well as design of the protectors. The Mudline ESP has two pumps powered electrically in parallel and arranged in series hydraulically. In this project, the equipment has evolved in relation to the previous installations, in particular the inclusion of chemical injection, access to hot stab and the capability to receive a flow homogenizer.The system will begin operation in 2015 and it is expected that its runlife will be similar to the standard equipment installed in the well, but with lower intervention costs. Possible improvements for the next projects are the use of sensors on both pumps and the installation of the system with even simpler and cheaper vessels.Since the assembly of the pump and the whole skid is done onshore, the process can have a better control and supervision. Also, an integration test is performed before the system installation, which allows a complete evaluation of its performance.

This paper provides a general overview of the subsea Electric Submersible Pump ESP skid boosting system, and describes the technologies introduced to make the ESP system more robust, the resources brought together to move the required assembly tasks to a controlled onshore facility, the equipment validation program, and the initial experiences in installation and operation of the system.Production of the 17°API heavy oil from Jubarte requires some means of artificially lifting fluids to surface. The high installation and intervention costs associated to subsea ESPs has prompted an operator to search for alternate boosting systems. The mudline ESP skid provides a solution for more cost-effective boosting of fluids to surface in deepwater fields.The experiences gathered and results obtained with the operation of MOBO (Modulo de Bombeio, which is Portuguese for pumping module) ESP systems in the Jubarte and Golfinho fields have encouraged the operator to develop new ways for producing oil from these offshore fields using techniques to reduce considerably the installation and workover time and cost. In this way, the development of Jubarte Phase III uses a different arrangement for the mudline ESP, with the equipment installed in a horizontal skid instead of a vertical module. The skid comprises two horizontal ESP systems connected hydraulically in series and powered electrically in parallel by a medium-voltage drive located in a floating production, storage, and offloading (FPSO) platform. This setup reduces the size of the subsea assembly and allows use of a vessel of opportunity for deployment instead of a rig.The subsea ESP skid concept was developed and tested on two previous occasions: an extended well test in Espadarte offshore Brazil and a production module in the Cascade-Chinook development in the Gulf of Mexico. In this new project, the equipment has evolved in relation to the previous installations, with a new and larger ESP system, the inclusion of chemical injection, access to hot stab, and the added capability to install a flow homogenizer.The skid system design aims at improving economics for production of heavy oil fields while also addressing ESP run life concerns in these low gas volume fraction and high boost pressure deepwater applications.

In recent past, most of Brazil's oil production was generated from siliciclastic reservoirs in scenarios of deep and ultra-deep water of the Campos Basin, being much effort focused on developing technologies to guarantee production optimization. Despite the great experience acquired by Petrobras in evaluating dynamic behavior of deepwater fields, new production scenarios of heavy oil reservoirs are even more challenging due to their high oil viscosity that generates emulsion stability.Jubarte field (siliciclastic turbidite reservoir) development features 15 heavy oil producing wells tied to P-57 floating production storage and offloading (FPSO) vessel. Each well is equipped with a 1500HP electrical submersible pump (ESP) installed in a caisson located 210 meters away from the wellhead in water depths varying from 1260 to 1360m. Over the last 3 years, since Jubarte first oil, the maturity curve of the wells has revealed a scenario where ESP has been recognized as a critical component of the subsea production system to sustain well production. Normally adopted in projects to anticipate production during the early years, ESPs in Jubarte field have been presenting an outstanding performance, overcoming oil viscosity limitations or unpredictable multiphase flow regime with strong emulsion formation (both tied to injection of viscosity reducers and the advent of natural free water from the reservoir).Operating ESPs installed at the seabed poses challenges in many aspects. Understanding the flow pattern (to ensure effective startup and run in optimal conditions), pump and caisson fluid dynamic behavior (to allow the pump ride through some observed inflow discontinuities) are two essential issues.This work aims to introduce the phenomenon of flow intermittency experienced during the operation of ESPs installed in vertical caissons in Jubarte field. It also demonstrates the engineering approach and the main proposed solutions to overcome the problem of well instability. The advantages obtained through the injection of demulsifier upstream the ESP are finally presented as a key element to promote stability, allowing ESP to run properly with significant gains in production rate.