Innovations for Deepwater Jubarte Heavy Oil

Abstract

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper OTC 19083, "The New Deepwater Oil and Gas Province in Brazil: Flow Assurance and Artificial Lift: Innovations for Jubarte Heavy Oil," by Giovani Colodette, Carlos A.G. Pereira, Cezar A.M. Siqueira, Geraldo A.S.M. Ribeiro, Roberto Rodrigues, Joao S. de Matos, and Marcos P. Ribeiro, Petrobras, originally prepared for the 2007 Offshore Technology Conference, Houston, 30 April-3 May. The paper has not been peer reviewed. The full-length paper presents a review of the artificial-lift (AL) and flow-assurance challenges faced in the exploitation of Jubarte heavy oil, starting from the features of the Pilot Phase. The challenges posed and innovations proposed and implemented for Phase 1 field development, as well as expectations for the subsequent Phase 2, are detailed. Introduction The Jubarte field is in the north part of the Campos basin, approximately 80 km offshore from the state of Espírito Santo, at a water depth between 3,280 and 4,922 ft. The field discovery occurred in January 2001, when an interval containing 17°API oil was identified in sandstones of Maastrichtian age. During the evaluation phase, a study based on the concept of value information supported the decision to drill a horizontal appraisal well. In February 2002, the well was drilled, with a 3,510-ft horizontal length, and was completed with an openhole gravel pack. The result was a well productivity index (PI) 13 times greater than the PI obtained with the vertical well. An extended well test (EWT) was proposed and approved. In the EWT, which started in October 2002, Petrobras made use of the floating production, storage, and offloading (FPSO) vessel Seillean, a dynamically positioned vessel with a rig capable of performing light workover operations. The well was connected to the FPSO through a 5 5/8-in.-inside-diameter drillpipe riser. Using an innovative solution, a 900-hp, 25,000-B/D-capacity electrical submersible pump (ESP) was installed above the wet tree. In case of ESP failure, the drillpipe riser could be recovered by the FPSO for pump retrieval and replacement. The good results obtained in the EWT led to its continuation in a Pilot Phase, which lasted until January 2006. After the Pilot Phase, the Jubarte Phase 1 production was started with the FPSO P-34. This new development phase comprises four production wells, and a 60,000-B/D oil-production rate is expected. One of the wells represents an innovative installation of the ESP on the seabed, another well has a downhole ESP installed, and the remaining two wells produce with gas lift (GL). GL backup can be used in the ESP wells while awaiting repair in case of pump failure. The ultimate Jubarte production system (Phase 2), to be implemented in 2011, will comprise 11 new wells plus the four wells from Phase1, and seven water-injection wells, connected to the FPSO P-57. During this production phase, all production wells will run ESPs installed on the seabed as the main AL method, with GL as backup.