Page 526 - Petrophysics
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494 PETROPHYSICS: RESERVOIR ROCK PROPERTIES
6& oT*1.rae Loss)
I
Figure 8.3. Modes of fracture formation.
oil staining
Figure 8.4. ReservoirBuids in shear fractures, Monterey formation, California [9].
Type 2: In type 2 reservoirs, the matrix already has very good
permeability. The fractures add to the reservoir permeability and can
result in considerably high flow rates, such as in the Kirkuk field of Iraq
and Asmari fields in Iran.
Type 3: In type 3 naturally fractured reservoirs, the matrix has
negligible permeability but contains most if not all the hydrocarbons.
The fractures provide the essential reservoir permeability, such as in
the Monterey fields of California and the Spraberry reservoirs of West
Texas.
Type 4: In type 4 reservoirs, as shown in Figure SSb, the fractures
are filled with minerals. These types of fractures tend to form barriers
to fluid migration and partition formations into relatively small blocks.
