1. MÆRSK OLIE OG GAS AS – GYMNASIE OPGAVE - 2008

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3. 3 The Geology Case – now it is your turn! MY OWN LITTLE OILFIELD THE MOLO FIELD OPGAVE OPGAVE – beregn olie mængden i et reservoir

4. 4 Gross Rock Volume is: Volume of rock containing our reservoir STOIIP (Stock Tank Oil Initially In Place) or GIIP (Gas Initially In Place) is: Amount of hydrocarbons present in our reservoir RESERVES are: Hydrocarbons we can produce (given present conditions) OPGAVE – Baggrundsinformation 1

5. 5 Recovery Factor is depending on: Reservoir Quality & Conditions Oil and Gas Type Number of Production Wells and Type (Cost) Production Method (Enhanced Recovery) RESERVES = [STOIIP] · [Recovery Factor] OPGAVE – Baggrundsinformation 2

6. 6 YOUR FACTS: 1)We have 2 seismic profiles across the reservoir 2)The MOLO-1 well penetrated the top of the reservoir at a depth of XXXX feet 3)An oil-water contact was found in MOLO-1 at a depth of XXXX feet 4)The average porosity (Φ) was found to be 0.XXX (XX.X vol.%) 5)The penetrated reservoir is reduced by interspaced non-reservoir rock → N/G ratio of 0.90 (90 vol.%) 6)The average water saturation (S w ) is 0.XX (XX vol.%) 7)The Formation Volume Factor (FVF) is 1.2 (the reduction in oil volume due to loss of gas content when moving from reservoir pressure and temperature to surface conditions) 8)The Recovery Factor (RF) is estimated to be 0.25 (i.e. 25 % of the STOIIP will be produced to surface). OPGAVE – Baggrundsinformation 3

7. 7 YOUR TASK: 1)Calculate the Gross Rock Volume (GRV) 2)Calculate Stock Tank Oil Initially In Place (STOIIP) 3)Calculate the Reserves OPGAVE: My Own Little Oilfield 1

8. 8 OPGAVE: My Own Little Oilfield 2 EAST SOUTH NORTH MOLO-1 well Seismic Profiles WEST

9. Top of Reservoir 1000 feet 5700 6000 6300 6600 6900 7200 7500 7800 NOTE – feet! MOLO-1 well Oil-Water Contact / Transition Zone OPGAVE: My Own Little Oilfield 3 NOTE – meter!

10. MOLO-1 A wireline log showing the porosity and hydrocarbon saturation profile from the well Approximately 180 ft of chalk oil-reservoir h  60 meters OPGAVE: My Own Little Oilfield 4

11. 11 OPGAVE: My Own Little Oilfield 5 Apply a known geometrical shape to the reservoir shape: The Spherical Cap α h

12. 12 OPGAVE: My Own Little Oilfield 6 Gross Rock Volume is then the volume of a spherical cap with a height of h and a radius of α h is estimated using the log from the well – You then find α from the seismic profiles Calculate GRV from this expression (expect a large number!): GRV = 1/6 · π · h · ( 3 · α²+h²) α h 0

13. 13 OPGAVE: My Own Little Oilfield 7 Gross Rock Volume (GRV) Net to Gross (N/G) Porosity (Φ) Oil Saturation (S oil equal to 1 minus Water Saturation S w ) Oil Formation Volume Factor (FVF given as a value of 2) STOIIP = GRV ∙ N/G ∙ Φ ∙ S oil / FVF Calculate STOIIP using this expression (the unit at this stage is m 3 ):

14. 14 OPGAVE: My Own Little Oilfield 8 Reserves = STOIIP million bbls ∙ RF STOIIP million bbls = STOIIP m 3 ∙ 6.29 / 1,000,000 We now re-calculate STOIIP in m 3 to STOIIP in million bbls using this expression: Finally the reserves are calculated given a recovery factor of 0.25 (25%):

15. 15 OPGAVE: My Own Little Oilfield 9 – Excel regneark til beregning

16. How can I learn more? http://www.maerskoil.com MÆRSK OLIE OG GAS AS The End