Abstract

In the Amenam-Kpono Field, six of the hydrocarbon bearing reservoirs encountered are currently developed. The Main Reservoir (R4) is characterized by vertically stacked sand bodies with intercalated shale layers, laterally well extended.

In the initial reservoir study, a low vertical reservoir permeability (Kv/Kh=0.01) and maps of vertical transmissibility within these shale layers were implemented in the dynamic model.

In fall 2007, Amenam East well confirmed an excellent lateral communication with Amenam Main Field through the aquifer and highlighted the presence of multi disconnected hydrocarbon bearing flow units within R4 reservoir of the Amenam-East structure.

It was assumed in the initial Field Development Plan that these shale layers would play a crucial role in fluid dynamics and hydrocarbons recovery. The initial dynamic model was used to optimise well location and perforation strategy.

With 35 development wells drilled and almost five years of production (1st oil in July 2003), the significant impact of vertical shale barriers was confirmed and 4 main dynamic units were identified in the R4 reservoir. Data acquisition during the development phase and early production life of the field with pressure data, interference tests and gas tracers yielded very significant results, essential to optimise the development strategy and to establish a proper reservoir management scheme of the Amenam-Kpono field.

A limited number of corrective actions were implemented, mainly with 4 additional wells in 2007–2008, drilled to sustain pressure and/or to enhance recovery in the under developed R4 bottom unit.

Introduction

The offshore Amenam field discovered in 1990 is an oil and gas condensate field, located 35 km south of the Niger Delta (Fig.1). Water depth of Amenam Field is 40 meters. The Amenam Field is part of the OML 99 and has been unitized with the Mobil (Exxon) Kpono Field.(OML70) The unit agreement was signed in 1997 between NNPC (60%) Mobil (9.6%) and EPNL (30.4%) as operator.

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