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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