Abstract: Prognosis of Dynamics of a Lithogeochemical Equilibrium of "Oil-reservoir" System in Terrigenous Reservoirs

IZOTOV, V.*, L. SITDIKOVA, R. MUSLIMOV, and N. GATIJTULLIN

Hydrocarbon reservoirs should be considered natural lithogeochemical "oil-reservoir" system being in equilibrium. Hydrocarbon extraction, especially when using chemical and physical methods, results in upsetting an equilibrium. Both positive and negative consequences of that process are possible. Detailed lithogeochemical investigations of reservoirs permit to forecast this upsetting and to select an optimum method of affecting the reservoir in order to obtain a maximum long-term oil recovery.

To forecast the dynamics of the system, it is necessary to take into consideration all the factors connected with mineralogy and structure of the active part of reservoir rocks. This active part, usually including the cement of terrigenous reservoirs, can be a complex of crystalline and fine-grained minerals: clay minerals, fine-grained quartz, hydrous ferric oxides, carbonates. Behavior of these minerals depends on a complex of chemical reagents applied for an increase in oil recovery. Clay minerals are known to swell, being affected by a number of chemical reagents, including water. That results in occulsion of pore channels and oil recovery decrease.

Permission is required to select flexible technologies for favorable effect on the layer, for forecasting the dynamics of lithogeochemical equilibrium and directing the shift in equilibrium for optimum oil recovery.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria