Wednesday, October 28, 2015

How Oil Beds were Formed

From An Exclusive For the Daily Record January 2, 1943 
By Ray E. Colton, Oil And Gas Science Writer 
Geologist Tells How Oil Beds Were Formed In This County

The dying Marine life is believed, on the basis of what observations have been made here in Lawrence County, to have formed oil source beds in the form of muds, clays, silicates and carbonates. The agency which solidified this organic mass of marine life was in all probability, subterranean heat. The mass lay mellowing for countless centuries, during which time it was being constantly augmented by additional remains of marine animal and marine vegetable manner.

Migrated To Porous Strata
Finally the mass began to migrate to what is termed as adjacent porous strata i.e. such limestones, sandstones and shales as possess the physical attraction of porosity necessary to entrap the migrating oil mass in their strata folds.
Various forces such as induration of the mass, earth movement during land mass adjustments such as the local LaSalle Uplift, or hydrostatic pressure of accumulating natural gases, could have been the cause of the migration of the oil mass from the source beds to the adjacent porous strata.

Receiving Rocks Permeable
The receiving or reservoir rocks to which the migrating oil mass was attracted, had to be permeable as well as porous, and they had to be encased in what is termed impermeable strata. This was necessary, in order that the contained hydrocarbons originating from the dying marine life, might have freedom of movement within the reservoir, yet have no escape from it once entombed.
Certain types of rocks such as in the igneous, metamorphic, and those of which have been derived from granitic sources, cannot be a possible source of commercial oil owing to their non- porosity. Had these types of rocks, which are found to be in the minority here in Lawrence County, one- time have contained any oil obtained through the agency of seepage, the conditions which have altered them to their present state, would have long since dissipated any  petroliferous material which such rocks might have contained.

The subsurface structures known to exist beneath Lawrence County indicate that this area will produce oil and gas for many years to come.

Ladies, have you made your reservations for Lunch and Learn Nov4?