Asset Management through the Reservoir Life Cycle
Authors: Satter Abdus 
Published: October 2008

This paper presents asset management concept and process and examples of sound reservoir management practice in developing a new field, revitalizing a mature old field, and developing a water flood project after primary depletion. Useful information is included about reservoir performance analysis and economic results for these example reservoirs at various stages of the reservoir life cycle.

Introduction

A reservoir's life begins with exploration that leads to discovery, which is followed by delineation of the reservoir, development of the field, and production by primary, secondary, and tertiary means, and finally to abandonment (Figure 1).

This Paper Presents:

A brief review of asset management concepts and process.Examples of sound reservoir management practice used to enhance economics in projects at various stages of the reservoir life cycle:Development of a newly discovered offshore oil field.Revitalization of a mature offshore oil field.Development of a water flood project. Details of reservoir data, performance analysis techniques and results can be found in the published references 1, 2,3,4,5.

Asset Management

The ultimate goal of asset management is to maximize economic benefits from the company's upstream, midstream, and downstream assets (Figures 2 and 3) by optimizing recovery while minimizing capital investments and operating costs.

A sound management practice in upstream operation consists of setting goal, developing and implementing plan, monitoring and evaluating performance, and revising necessary unworkable plans (Figure 4). This can be achieved by integration of multi-disciplinary professionals, technologies, tools, and data. This is a dynamic process throughout the reservoir life.

Example 1 - Development of a Newly Discovered Offshore Oil Field.

This example presents how a team of geoscientists and engineers developed an economically viable plan based upon an integrated reservoir model, reservoir performance analysis, and economic evaluation. Natural depletion or natural depletion augmented by water injection, and well spacing requiring the number of wells and platforms were considered.

Reservoir Data.

Rank Wildcat Well No. 1 was the example offshore oil field discovery well. The field is analogous to Gulf Coast reservoirs. Wells 2, 3, 4 and 5, were drilled to delineate the field (see Figure 5). A drill stem test was performed at the discovery well and the results indicated two productive zones at 4000 ft and 4500 ft depth. Initial production rates from the sand zones were 875 STBOPD and 1,456 STBOPD, respectively. Well No. 4 was a dry hole while Well No. 3 penetrated the oil-water contact.

Preliminary data indicated that the under saturated reservoirs had good porosity, permeability, and contained light oil. This field had as much as 55 MMSTB of original oil-in place in the top layer and 102 MMSTB at the bottom layer. The field had a significant amount of potential reserves.

Based upon permeability variation and to facilitate performance analysis, the upper sand was subdivided into two layers, while the lower sand was subdivided into three layers.

Development and Depletion Strategy.

An integrated geoscience and engineering team was charged to address the following main questions in order to come up with an economically viable development and depletion strategy: