Russian Far East

The regions of the Russian Far East that have petroleum potential are the Sea of Okhotsk, parts of its rim, Sakhalin Island, and the Northwest Pacific Rim. Seventeen basins are recognized. These are filled with Cenozoic clastic and volcanic deposits thousands of meters thick. Bituminous cherty limestone and shale source beds similar to the Domanik of the Volga-Ural province, Bazhenov of West Siberia, and Monterey of California are expected in these basins.

The published literature on this region is vast. Three plays are described here: rift basins of Amur region, serpentinite reservoirs of Sakhalin, and the TINRO basin in the northern part of the Sea of Okhotsk.

Rift basins of Amur region. A system of rift basins (grabens) in northeast China extends to the northeast across the Amur River into Russia, where they are associated with the Lobey-Birofel'd section of the Tanlu fault. Abundant brown coal is present in these grabens. Birofel'd graben contains more than ten coal beds in the Chernorechen Formation and 16 in the Ushuman Formation. Lesser amounts are found in the other grabens. The minimum amount of methane generated by these coal beds to depth of 600 m is estimated at 1.2 tcf, and total from all the organic matter is placed at 3.7 tcf (Petroleum Geology, vol.33 no. 3, p. 213, 1999).

Serpentinite reservoirs of Sakhalin. Seventy fields have been discovered on Sakhalin Island and on the adjacent shelf. Seven plays are recognized: Paleocene-Eocene, Oligocene, earlymiddle Miocene, middle-late Miocene, late Miocene (Nutov Fm), late Miocene (Pomyr Fm), and Pleistocene. The best reservoirs are sandy deposits of the delta of the paleo-Amur River, the front of which in the early Miocene was in the southern part of the present shelf. This shifted in the late Miocene to the northern part of the shelf. Fractured serpentinites have only recently bee considered as targets. They are present along the entire shelf of North Sakhalin. The main source rocks are siliceous argillite of the Pil Complex, which are 1.5-2.5 km thick, carry up to 1.8 percent organic carbon, and underlie and overlie the serpentinites along thrust planes. Resources are assessed at 65,000 tons per sq km for the serpentinite zone of Vostochno-Oduptu zone. Total in place resources are assessed at 2.1 BBOE (Petroleum Geology, vol. 33, p. 223, 1999).

TINRO depression. This depression is offshore in the Sea of Okhotsk south of Magadan. Stable subsidence extended through the entire Cenozoic with accumulation of more than 9 km of marine clayey and siliceous-clayey oil-source rock. Clastics shed off the continent on the north will have supplied reservoir rock. Analogs are the Bazhenov of West Siberia and the Domanik of the Volga-Ural province. The TINRO source beds may be too thick and self-sealing, retaining their oil. Sands intertounging from the north, however, would be supplied with copious oil

Copyright James Clarke 1999. You are encouraged to print out copies of this news letter and to forward it to others. HREF="index.html">Russian Far East