V. Check carefully for possible source and reservoir rocks and entrapment conditions. 



A. Source Rock 



1. What rock types would probably be most favorable, and what percentage of 

 these types are represented in the total section? 



2. What are the sedimentational and structural relationships between possible 

 source strata, reservoir strata, and entrapment conditions? 



3. Is permeability sufficient to permit migration from the source type to as- 



sociated porous types? 



4. What are the thickness, lithologic variation, and distribution? 



5. What is the percentage of organic material, and how is it distributed? 



6. Under what environments were the strata developed? 



B. Reservoir Rock 



1. What are the favorable types (sandstone, fractured or porous carbonate, 

 fractured shale, argillaceous sands) ? 



2. What relationships exist between reservoir rock and structure? 



3. Could the strata qualify for a possible source as well as for a reservoir? 



4. What about thickness, extent, porosity, and permeable variability? 



5. What are the relationships to erosional surfaces, and what is the relationship 

 of time of origin and migration to these erosional surfaces? 



6. Are the strata in reach of economic drilling? 



7. What about A.P.I, gravity variations? 



C. Entrapment Conditions 



1. Are the trap conditions controlled by sedimentational or structural irregu- 

 larities or both? To what extent? 



2. What are the relationships between the trap feature, source rock, and 

 reservoir rock? 



3. What are the extent, pattern, and trend of the trap? 



VI. Describe the geological history of the area. 



A. Sedimentational History 



To decipher the sedimentational history of an area, one should consider the 

 following points: 



1. Period and extent of oscillations. 



2. Environmental conditions prevalent during various oscillatory stages. 



3. Sedimentational patterns developed during the oscillation periods. 



4. Source direction of sediments. 



5. Post-depositional changes. 



6. Relation of sedimentary patterns to tectonic adjustments. 



B. Structural History 



1. What effect did structural adjustment during sedimentation have on de- 

 velopment of the stratigraphic pattern (faulting, local and regional warping 

 and arching, tilting) ? 



2. When did the major periods of folding and erosion occur? What about the 

 degree and variation in tectonism? 



A clear picture should be formed of erosional intervals and chances of survival of 

 the oil, and one should bear in mind the deformation of strata, degree of erosion, and 

 subsequent blanketing by impervious rock. 



Regional reconnaissance geological investigations demand accurate and multiple field 

 observations and an ability to place these data in their proper category prior to final analysis. 



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