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ACKNOWLEDGEMENTOur immense gratitude goes out to the management and staff of the Institute of Petroleum Studies especially Mr. Francis Fusier for working assiduously to ensure the smooth running of our MSc program and for putting all required logistics in place for a successful one week of STATIC RESERVOIR Simulation with PETREL software. Our heart goes out to TOTAL Exploration and Production Nigeria Ltd for the rare opportunity granted us in funding our MSc degree program with the IPS initiative. Finally, we thank God for His constant strength and guidance especially in this tough and mentally-challenging environment, and extend our thanks also to the entire exciting, fun-loving, intelligent and smart individuals that make up Batch Seven of IPS.

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CHAPTER ONE1.0 IntroductionThe Gulfalks field (about 6115N, 215E) is one of the three giant oil fields located at the edge of the North Sea Plateau, located on the western flank of the North Viking Graben (Norwegian sector), also with high gas accumulations. The sediments are coarse sands due to their proximity to submerged beach zone. Gullfaks field has no pockmark structures probably due to coarseness of sediments. The gas found at Gullfaks, of which 98% of it is methane can easily migrate vertically through the porous sediments. Numerous shallow gas accumulations lie at a depth of about 300-450 m below seafloor. The source rock of Gullfaks Oil field is from the Permian age. These gas hydrocarbons migrated to the mean, economical, interesting reservoirs of Jurassic age. The origin of methane is fossil (Hovland and Judd, 1988). The temperature at the reservoir is 8C. The Gullfaks field (see figures 1.1 and 1.2) comprises marine and fluviodeltaic sandstone reservoirs of the Middle Jurassic Brent Group. The Broom, Rannoch, Etive and lower Ness formations represent the deltas advance or progradation, while the upper Ness and Tarbert formations represent its retreat or retrogradation. The intensely faulted and compartmentalized structure contains an accommodation zones sandwiched between a system of strongly rotated fault (domino-type) blocks to the west and a horst complex to the east. Some of the crestal areas have been eroded and are directly overlain in places by the baseCretaceous unconformity.

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EXECUTIVE SUMMARYThis is a project on the static reservoir modelling of the Joana field: an oilfield located in the Paris Basin at 300km South-East of France. The field was discovered in the 1960s, drilled in the 1980s and the 1990s with one of its wells still producing at present. Data was obtained from the existing Joana field wells in the form of geological and seismic survey, sedimentology, well correlation, coring, logging, fluid properties, and production data. These were all quality-checked, prepared and geostatisitically extrapolated as inputs to be used in the characterization of the reservoirs of the field. A 3-D static model of the field was produced using the Petrel software which encompassed the gridding, layering, facies modelling, fault modelling, zonation, etc of the field. This threw more light on the overall structure of the reservoir and was used in the calculation of the Original Oil in Place (OOIP) for the two major scenarios chosen. That is, for the connected reservoirs case, a value of 1,394 MM bbls OOIP was obtained while the assumption of unconnected reservoirs yielded 478 MM bbls manually and the software-calculated value as 403 MM bbls. Economical analysis of the field (assuming a recovery factor of 0.25 and a price of $65 per barrel of oil), a gross revenue of $22.70 billion was obtained for the connected reservoirs, $7.77 billion for the unconnected reservoirs (manual) and the software calculated as $6.50 billion. On the basis of all of the above, a recommendation for the upscale of the model to a dynamic one was made with a view to producing the field as 4

early as possible. 6RESERVOIR MODELLING PROJECT REPORT JULY 2009 (BY NWATU, VICTOR OKECHUKWU AND OLAJIDE, FESTUS OLATEJU.)

TABLE OF CONTENTSACKNOWLEDGEMENT .................................................................................................. 4 EXECUTIVE SUMMARY ................................................................................................ 5 TABLE OF CONTENTS .................................................................................................... 6 LIST OF FIGURES ............................................................................................................ 9 LIST OF TABLES ............................................................................................................ 11 CHAPTER ONE: GENERAL INTRODUCTION ........................................................... 12 1.1 OBJECTIVES OF THE STUDY ....................................................................... 12 1.2 SCOPE OF THE STUDY .................................................................................. 12 1.3 DATA USED ..................................................................................................... 13 1.4 METHODS ADOPTED .................................................................................... 13 1.5 HISTORY OF THE PARIS BASIN .................................................................. 14 1.6 STRUCTURE OF THE PARIS BASIN ........................................................... 15 1.7 STRATIGRAPHY OF THE PARIS BASIN .................................................... 16 1.8 THE PETROLEUM SYSTEM .......................................................................... 17 1.8.1 Source Rock ................................................................................................ 20 1.8.2 Reservoir Rock ............................................................................................ 20 1.8.3 Traps ........................................................................................................... 21 1.8.4 Migration .................................................................................................... 21 1.8.5 Seals ............................................................................................................ 21 1.8.6 Time............................................................................................................. 22 CHAPTER TWO: SEISMIC INTERPRETATION AND ANALYSIS ........................... 23 5

2.1 PICKING OF TOPS ........................................................................................... 23 2.2 TIME DEPTH CONVERSION ......................................................................... 23 2.3 FAULT PATTERNS .......................................................................................... 24 CHAPTER THREE: SEDIMENTOLOGY OF JOANA FIELD...................................... 27 3.2 STRATIGRAPHY OF JOANA FIELD.................................................................. 30 3.3 CORRELATION ............................................................................................... 32 7RESERVOIR MODELLING PROJECT REPORT JULY 2009 (BY NWATU, VICTOR OKECHUKWU AND OLAJIDE, FESTUS OLATEJU.)

CHAPTER FOUR: PETROPHYSICS ............................................................................. 36 4.1 LOGS AND INTERPRETATION ..................................................................... 36 4.1.1 Identification of the Reservoir zones........................................................... 38 4.1.2 Identification of Non-reservoir areas (shale zones) ................................... 39 4.1.3 Summary of the Petrophysical Analysis of the Logs ................................... 39 CHAPTER FIVE: STATIC RESERVOIR MODELING ................................................. 41 5.1 DATA QC/QA AND ANALYSIS ..................................................................... 41 5.2 STRUCTURAL MODELING ........................................................................... 41 5.3 COMPARISON OF THE GEOSTATIC MODELLING METHODS .............. 41 5.1 DATA QC/QA AND ANALYSIS ..................................................................... 42 5.1.1 Data import and QA/QC of input................................................................ 42 5.1.2 Creation of surfaces .................................................................................... 42 5.1.3 Layering and Gridding of surfaces ............................................................. 44 5.1.4 Matching facies with wells .......................................................................... 45 5.1.5 Correlation of reservoir logs. ..................................................................... 47 5.2 STRUCTURAL MODELLING ........................................................................ 48 5.2.1 Fault modeling ............................................................................................ 48 5.2.2 Scaling-up of well logs parameters............................................................. 49 6

5.2.3 Scaling-up of Net-to-gross. ......................................................................... 53 5.2.4 Facies modeling .......................................................................................... 54 5.3 COMPARISON OF THE VARIOUS GEOSTATIC MODELLING METHODS 60 CHAPTER SIX: CALCULATION OF OOIP .................................................................. 62 6.1 MANUAL CALCULATION OF OOGIP .............................................................. 62 6.1.1 Connected Reservoir ................................................................................... 64 6.1.2 Unconnected Reservoir ............................................................................... 65 6.2 OOIP CALCULATION FROM PETREL .............................................................. 66 6.1.2 Connected Reservoir ................................................................................... 66 8RESERVOIR MODELLING PROJECT