Roncador Field, Strategy of Exploitation
Authors: Pádua Kleber G.O. , Stank Carlos V. , Soares Carlos M. , Moreira Jose V. 
Published: October 2008

Roncador is a large deep water field with a complex hydrocarbon distribution located in the northern part of the prolific Campos Basin, offshore Rio de Janeiro State, Brazil. The development of the field is currently underway and because of the geological uncertainties and operational risks it requires the construction of potential production forecasts under various likely scenarios. This paper summarizes an interdisciplinary study performed together with the drilling of appraisal wells to plan the optimum field development and the exploitation strategy for Roncador Field. The simulation study which incorporated dynamically the data from appraisal wells predicted the field performance under diverse geologic models, fluid behavior, reservoir characteristics, drive mechanisms, completion schemes, production configurations and surface facilities. The results led to the design of a phased approach (sequential three phase development project, Modules I, 11, 111) with different alternatives depending on the geological scenario and hydrocarbon characteristics. This would favor the financial planning and minimize the geological and operational risks of the project. They also suggest a water injection secondary recovery process encompassing horizontal wells with the purpose of maintaining reservoir pressure above the bubble point, accelerating the production and reducing the number of wells (slots).

Introduction

Roncador is a large (OOIP around 1.5 billion sm3) deep water (water depth from 1500 to 2000 m) oil field with a complex hydrocarbon distribution (API gravity from 12 to 3 1 degrees) located in the northern part (120 km of SIo Tome Cape) of the prolific Campos Basin, Brazil, see Fig. 1. The discovery well was drilled in October 1996 andshowed a potential initial oil production rate of 1600 sm3/d with a 31" API oil gravity. Commercial oil production comes from turbidite sandstone reservoirs of the Carapebus Formation of Maastrichtian Age. The development is currently underway and because of the geological uncertainties (appraisal stage) and operational risks (deep water environment) it requires the construction of potential production forecast under various probable scenarios. The performance predictions are based a1 integrated 3-D full field reservoir simulations which encompass surface and sub-surface facilities. The main challenges are to :estimate future rates with a reasonable degree of precision;contribute towards optimizing the development concept and the production strategy;. maximize the recovery factor, NPV, and oil rates over time;quantify uncertainty in prediction of future production rates.

Geological Model

Three dimensional (3D) seismic and well logging survey provide information on structure and reservoir quality/extent for the geological model. However, because of the level of knowledge at this early stage of development and the fields great areal extension (approximately 130 km2), there is still a high degree of uncertainty about the geological system. A detailed description of the field is presented by Rangel et al (1). A net oil thickness map and a geologic section are presented on Figs. 2 and 3. Average parameters of the geological model are presented in Tab. 1. The external geometry of the field is defined to the north and east by dipping and to the south and west directions by pinchout. The field is assumed to be underlain by an aquifer with an uncertain water volume.