Prospects for deep and ultradeep oil and gas deposits in U.S.S.R.

In the U. S. S. R., so far, none of the hydrocarbon pools at depths exceeding 3500 m have been exploited. There are reasons to believe that large accumulations exist even below 5000 m depths, in areas shown on the map (fig. 1). Almost nine-tenths of proved economic reserves of oil and gas at shallow depths lie in terrigenous materials, the remainder in carbonates, in fissure-type-collectors. It is believed that the latter type of collectors will be found to be more abundant at greater depths. -- V. P. Sokoloff