Page 216 - Geology of Carbonate Reservoirs

Type IV Fractures Fractures Create Barriers to Flow Reservoirs commonly compartmentalized Wells underperform in ow comparison to matrix fl capabilities Recovery factor highly eld variable across fi Permeability anisotropy commonly unlike that in adjacent fractured reservoirs with different fracture styles

Type III Fractures Fractures Provide Permeability Assist response to secondary recovery Interconnected reservoirs common

IV Highly anisotropic permeability Commonly can have unexpected Commonly have poor correlation between log response, core
– Drainage areas commonly elliptical analyses, and well test or performance data
Commonly Encountered Problems Involved in Fractured Reservoir Types I

Type II Fractures Fractures Provide Essential Permeability - to - fracture communication Poor matrix leading to poor matrix recovery efficiency and disastrous secondary recovery results — Possible early water encroachment requires controlled production rates Fracture intensity and dip angles critical Development pattern must be tailor

Fractures Provide Essential Porosity and Permeability Often have rapid decline curves Possible early water encroachment — requires controlled production rates Difficult to determine drainage area size and shape Difficult to constrain reserve Development wells add production rate but not additional reserves Adapted from Nelson (2001) .
TABLE 7.2 Type I Fractures calculations Source :

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