--> --> ABSTRACT: The Effect of Heating Rate on Kerogen Maturation and Oil Generation, by M. Arif Yukler, Wallace G. Dow; #91003 (1990).
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ABSTRACT: The Effect of Heating Rate on Kerogen Previous HitMaturationNext Hit and Oil Generation

M. Arif Yukler, Wallace G. Dow

Quantitative basin modeling studies with YUKLERPC software show that heating rate affects kerogen Previous HitmaturationTop indices differently and changes their correlation with the oil and gas generation zones. Source rocks exposed to high heating rates generate and expel petroleum more quickly and efficiently and at lower vitrinite reflectance maturities than source rocks experiencing low heating rates. The result is that lesser quality sources are required to achieve a given petroleum charge when heating rates are high and better quality sources are required when heating rates are low.

Peak oil generation for a typical type II kerogen occurs at vitrinite reflectance maturities of about 0.7 to 0.8 Ro and temperatures of 124 to 131°C for a normal heating rate of 1 to 3°C/m.y. When heating rates exceed 3°C/m.y. in hot or rapidly subsiding basins, peak oil generation occurs at maturities less than 0.7 Ro and temperatures less than 124°C. When heating rates are lower than 1°C/m.y. in cool or slowly subsiding basins, peak oil generation takes place at greater than 0.8 Ro maturities and temperatures above 131°C. Pyrolysis Tmax values, on the other hand, directly reflect petroleum generation, and their relationship with vitrinite reflectance varies with heating rate.

Heating rate also affects oil expulsion efficiency and migration distances. When heating rates are high, rapid oil generation results in higher pressure in the source rock oil phase than in the water phase, which leads to higher expulsion efficiencies by pressure-driven oil movement. Rapid fluid pressure buildup can cause stress fracturing within the source rock, which also increases expulsion efficiencies. The opposite is true when heating rates are low. There is a positive correlation between expulsion efficiency and the distance of oil migration for a given source rock. Heating rate is, therefore, an important factor in geochemical interpretation and prospect evaluation.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990