Source rock, definition

Micelles appear to be larger than the small size of the pore throats in the source rock at a depth of burial corresponding to the main zone of oil and gas generation. According to Tissot and Welte (1984), primary migration of hydrocarbons in micellar solution would definitely be limited down to a depth of about 2000 m. 

Temperature is a fundamental parameter that definitely influen ces the maturation of sediments. This has been shown empiricalyari T laboratory simulations use it as the "driving force" to induce maturation. In this way, the use of the thermal alteration index in geological materials allows one to qualify (37) source rocks as imature (.temperature below 609C), mature (able to produce oil -if the sediment reached temperatures of 60-1509C) and senile - ja ble to produce gas if the temperature surpassed 1509C. It must be always kept in mind that these transformations occurred along millions of years, and, consequently, all tentatives to simulate these processes in laboratory suffer a severe criticism of their validity. 

The effective-to-general shale thickness ratio is a factor which determines the ability (or inability) of hydrocarbons to migrate from source rocks. In this context, of definite interest for evaluating the amount of generated hydrocarbons were also the less thick shale beds in the Ghadames, Illizi, Triassic and Reggane Basins. 

Just as the use of more than one element strengthens the interpretation of a sample, so the collection of more than one type of sample broadens the base for interpretation of a survey. Results from well water and surface rock may be only indirectly related, yet both may be important to definition of the mineral potential. For example, groundwater samples might show evidence of a reducing environment and little or no uranium in solution, whereas analyses from the outcrop of the host formation could verify a good source of uranium in the rock. 

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