Abstract

Peregrino is a heavy oil field in the Campos Basin offshore Brazil operated by Statoil and has been in production since 2011. The viscosity difference between oil and water at Peregrino gives an unfavorable mobility ratio, and water flows with a higher velocity than the oil. Any means to limit the water flow from the wells may enable an optimization of oil production. Inflow Control Devices (ICDs) and Autonomous Inflow Control Devices (AICDs) have been evaluated as one of these means.

ICDs are devices designed to choke back high velocity flow, while AICDs are designed to choke back flow of less viscous fluids. The expected effect of both technologies in heavy oil applications such as Peregrino, is therefore to balance the inflow along the horizontal well section and choke back the flow of water compared to oil, resulting in a reduced water-cut. Reservoir simulations indicate improved recovery when utilizing such technologies at Peregrino. ICD and AICD devices have been used with success by Statoil in conventional oil fields at the Norwegian Continental Shelf, however there are no applications of ICD/AICD technologies in heavy oil fields such as Peregrino.

A technology qualification program has therefore been conducted by Statoil to qualify ICD and AICD technologies for use at the Peregrino field. A first phase consisting of extensive laboratory testing has resulted in both the ICD and AICD technologies being approved for field piloting. The second phase, currently ongoing, is consisting of the installation of ICD and AICD in pilot wells, and monitoring of the field performance. If successful, this would lead to full-field implementation at Peregrino, and would also be beneficial for other heavy oil assets in Statoil's portfolio.

This paper covers the technology qualification process for the use of ICD and AICD technologies at Peregrino, from the simulations and laboratory testing to the implementation in the pilot wells and monitoring of field performance.

Introduction

The Peregrino Field is located in block BM-C-7 of the Campos basin offshore Brazil. Statoil is the operator of the field and holds a 60% ownership in the field while Sinochem is the sole partner holding the remaining 40% ownership.

The Peregrino Phase 1 development was sanctioned in 2007 and comprises of one FPSO and two wellhead/drilling platforms. In the initial Peregrino Plan of Development (POD) a total of 37 wells were planned of which 30 were horizontal oil producers and 7 water injectors. The Peregrino field achieved first oil 9th of April 2011. The plateau production rate of 100 000 bbl/d was reached in May 2013.

Large volumes of oil in place, over 2 billion barrels in the currently developed area of the field, are found in a heterogeneous sandstone reservoir. The oil viscosity at Peregrino varies from 100 cP to 400 cP, and the average density is 14°API. The high contrast mobility between oil and water combined with the reservoir heterogeneity represents a challenge for oil recovery as it leads to water fingering effects that can result in early water breakthrough in producer wells.

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