1. Off-shore Oil Formation and Reserves
PART FIVE
Off-shore Oil Formation and Reserves

2. How Oil Is Formed
Oil reserves form when non-porous rock lies above porous rock. Oil seeps up through the porous rock & is trapped by the non-porous rock.
Bacterial action and extreme pressure from layers of sediment converted the organic matter to oil & gas.
Millions of years ago plants and animals of the oceans died & settled on the ocean floor.

3. Oil Reserves Pg. 183
Fold Trap: the up fold or anticline in the layers of the earth's crust form the reservoir.

4. Oil Reserves
Fault Trap: the vertical movement of the earth's crust forms a v-shaped reservoir.

5. Oil Reserves
Salt Dome Trap: The salt dome forms an up-fold in the earth's crust not unlike the anticline caused by tectonic forces.

6. Oil Reserves
Stratigraphic trap: has a former limestone reef as its porous rock feeding the reservoir.

7. Techniques Used to Locate Reserves
Before 1900’s
The search for oil was limited. Had to look along fault lines for oil seeping to the surface (EX: Jed & Granny Clampett and the “Beverly Hillbillies”).
After early 1900’s
Geologists knew to drill in gentle anticlines or faulted sedimentary rock where reservoirs of oil might occur. (Not always successful).

8. Techniques Used to Locate Reserves
Modern oil exploration on the seas
ships tow sound emitters and hydrophones to send sound towards earth’s crust.
different rock layers
reflect sound differently.
computers convert the sound data into 3D pictures of the ocean’s rock layers.

9. Techniques Used to Locate Reserves
“Wild cat” wells are drilled to test for oil:
if they strike oil then delineating wells are drilled to determine the size of the reservoir.
If they miss oil then the core samples are examined for evidence of oil.

10. Patterns of Offshore Oil Production
FIGURE 11.2 PG. 184
Most oil regions of the world are on land.
Oil regions under the ocean floor are concentrated in the North sea around the UK and in the Gulf of Mexico.
FIGURE Also shows that the North Sea and the Gulf of Mexico are regions of high offshore oil production.

11. Gulf of Mexico North Sea West Africa

12. Patterns of Offshore Oil Production
FIGURE 11.3 PG. 185
It also reveals that offshore oil production is increasing faster than land production of oil.
West Africa, especially around the Ivory Coast, seems to have high oil reserves and is increasing in oil production.