AN APPROACH TO WELL PLACEMENT AND PRODUCTION IN A GREENFIELD


Department Of Oil And Gas/Petroleum Engineering


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AN APPROACH TO WELL PLACEMENT AND PRODUCTION IN A GREENFIELD 

ABSTRACT:          

Reservoir development planning and well placement significantly affect hydrocarbon recovery. Therefore, strategic well placement and development techniques are essential to minimize the risk of unproductive drilling and also to maximize production within the reservoir.

This study presents an approach to well placement and production in a green field. A 3D static model of the green field was built using geostatistical techniques to distribute the various model petrophysical properties such as porosity, thickness, and permeability in order to provide reliable reservoir description for dynamic modeling. A dynamic model was constructed to evaluate various reservoir development problems, including well placement, number and types of wells to be drilled in the green field. The drilling of both vertical and horizontal wells was considered in the analysis. Finding the optimal length of the horizontal well to be drilled in order to maximize oil recovery and to properly develop the reservoir was considered a significant problem to address. A sensitivity analysis was carried out to evaluate the impact of horizontal well length on oil recovery. The vertical to horizontal permeability anisotropy (kvkh) was also studied in this work.

The results of the analysis indicate that horizontal well length influences cumulative oil production. Drilling a 3000ft. long horizontal well was found to produce a higher cumulative volume of oil than the oil recovery obtained from similarly placed horizontal wells but with shorter lengths of 2000 ft. and 1500 ft.

It is concluded that the methodology proposed in this study will find application in the development of a green field.

TABLE OF CONTENTS

Contents

ABSTRACT iii

ACKNOWLEDGMENT iv

DEDICATION v

TABLE OF CONTENTS vi

LIST OF FIGURES viiii

LIST OF TABLES x

CHAPTER 1 1

INTRODUCTION 1

Statement of Problem1

Objectives2

Methodology2

Facilities and Resources2

Organization of Report2

CHAPTER 2 4

LITERATURE REVIEW 4

Geological Background of the Field4

Reservoir Description4

Porosity and Permeability5

Literature Review6

Introduction6

Geostatistical Modeling of Property Distributions7

Well Placement9

Literature Summary11

CHAPTER 3 12

METHODOLOGY 12

DATA PROCESSING AND ANALYSIS 12

Data Acquisition12

Outline of Methodology12

Digitization of Structural and Isopach Maps of A-1 Reservoir12

Estimation of Porosity, Thickness, and Permeability14

Estimation of Original Oil in Place (OOIP)24

Reservoir Dynamic Modeling25

CHAPTER 4 31

RESULTS AND DISCUSSION 31

Introduction31

Case 1: Variation of a Horizontal Well Length31

Case 2: Variation of Kv/Kh33

CHAPTER 5 35

CONCLUSION AND RECOMMENDATION 35

Conclusion35

Recommendation35

REFERENCES 36

APPENDIX 39

APPENDIX A: NOMENCLATURE 39

LIST OF FIGURES

Structural and Isopach Map of A-1 Reservoir (Ertekin et al, 2001)3

Porosity Distribution of A-1 Reservoir (Ertekin et al, 2001)4

Permeability Distribution of A-1 Reservoir (Ertekin et al, 2001)5

Digital Terrain Model of A-1 Reservoir12

Contour Map of Sand Structure of A-1 Reservoir12

Porosity Distribution in Layer1: a) ordinary kriging

b) a plot of sequential gaussian simulation c)variogram model 15

Porosity Distribution in Layer 2: a) ordinary kriging

b) a plot of sequential gaussian simulation c)variogram model 15

Porosity Distribution in Layer 3: a) ordinary kriging

b) a plot of sequential gaussian simulation c)variogram model 16

Porosity Distribution in Layer 4: a) ordinary kriging

b) a plot of sequential gaussian simulation c)variogram model 16

Net Thickness Distribution in Layer 1: a) ordinary kriging

b) a plot of sequential gaussian simulation c)variogram model 18

Net Thickness Distribution in Layer 2: a) ordinary kriging

b) a plot of sequential gaussian simulation c)variogram model 18

Net Thickness Distribution in Layer 3: a) ordinary kriging

b) a plot of sequential gaussian simulation c)variogram model 19

Net Thickness Distribution in Layer 4: a) ordinary kriging

b) a plot of sequential gaussian simulation c)variogram model 19

Permeability Distribution in Layer 1: a) ordinary kriging

b) a plot of sequential gaussian simulation c)variogram model 21

Permeability Distribution in Layer 2: a) ordinary kriging

b) a plot of sequential gaussian simulation c)variogram model 21

Permeability Distribution in Layer 3: a) ordinary kriging

b) a plot of sequential gaussian simulation c)variogram model 22

Permeability Distribution in Layer 4: a) ordinary kriging

b) a plot of sequential gaussian simulation c)variogram model 22

Relative Permeability Curve24

Layer 1; map of initial pressure25

3.17 Layer 2; map of initial pressure 26

3.18 Layer 3; map of initial pressure 26

3.19 Layer 4; map of initial pressure 27

3.20 Layer 1; map of initial water and oil saturation 27

3.21 Layer 2; map of initial water and oil saturation 28

3.22 Layer 3; map of initial water and oil saturation 28

3.23 Layer 4; map of initial water and oil saturation 29

4.1 Case 1: oil production rate 30

4.2 Case 1: cumulative oil production 31

4.3 Case 1: water cut 28

4.4 Case 1: field pressure 31

4.5 Case 2: oil production rate 32

4.6 Case 2: cumulative oil production 32

4.7 Case 2: water cut 33

CHAPTER 1

INTRODUCTION

Statement of Problem

Reservoir development and well placement have been one of the existing challenges in the petroleum industry over the years. This is because different engineering, geological and economic variables affecting reservoir performance are practically involved.

More importantly, the decision on how to increase oil recovery and maximize the economic profitability of field development projects is the pivot point. Therefore, an extensive evaluation of certain decision variables such as reservoir properties, production scheduling parameters, type of well, location to drill new wells and an effective technique to obtain the best economic strategies are required. Also, consideration should be given to the spatial distribution of geological and rock properties such as porosity and permeability in order to locate potential hydrocarbon zones for drilling activities. This involves critical evaluation of development strategies to produce the greatest amount of hydrocarbons within the physical and expected economic limits.

Several techniques have been adopted to achieve efficient reservoir development process which significantly affects the productivity and economic benefits of an oil reservoir. However, the aim of this work is to evaluate the impact of well placement on cumulative oil recovery during the development of a green field.

In this study, reservoir simulation and spatial based modeling approaches will be used as key evaluating elements for the development of the greenfield oil reservoir to improve its productivity.

Objectives

The objectives of this study are to:

· Use geostatistical methods to distribute the petrophysical properties in building a 3D static model of the reservoir;

· Find the optimum number, type, and placement of wells required to develop the greenfield.

Methodology

The methods to be used include;

· Build a 3D static model of the green field by

o Digitization of structural and isopach maps of the A-1 reservoir

o Estimation and distribution of Porosity, Permeability, and Thickness at all locations in the reservoir

o Estimation of Original Oil in Place (STOOIP)

· Construction of a 3D dynamic reservoir model

· Use of the 3D dynamic model to find the optimum number, type, and placement of wells to develop the reservoir.

Facilities and Resources

The facilities and resources used for this project include;

· AUST library and internet facilities

· Technical and academic expertise of supervisor

· Structure and Isopach maps of A-1 reservoir

· Isopermeability map of A-1 reservoir

· Isoporosity map of A-1 reservoir

· Computer software programs such as: GIS, SGeMS, Sensor Simulator

Organization of Report

This report is organized into five chapters. Chapter one is the introductory chapter giving general information about the entire project. Chapter two gives in-depth information of the study area and reviews relevant literature related to this work. Chapter three places emphasis on data

processing and analysis. Chapter four covers the results and discussion. The last chapter which is chapter five concludes the project and provides the necessary recommendations.

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