Sakhalin Reservoir

Commonwealth of Independent States

NORTHERN SAKHALIN OIL/SOURCE ROCK RELATIONSHIPS

The study was undertaken to provide a uniform and comprehensive geochemical database from which to correlate oils and source rocks. A total of thirty-six (36) crude oils from nineteen (19) oil fields, and eighty-eight (88) source rock samples from twenty-one (21) locations were collected. Crude oil samples were selected to provide a regional representation of onshore production from which to compare with offshore oils on the northeast shelf. Some oils were collected from different pay and different age reservoirs within the same field to examine vertical variations. Source rock samples were generally selected from the same fields from which oils were collected in order to examine vertical variations. Source rock samples were generally selected from the same fields from which oils were collected in order to examine interbedded source-reservoir relationships. An effort was made to collect potential source rocks of different ages at each location to examine thermal maturity profiles. All source rock samples were core samples of subsurface strata at well locations.

The major objective of the study is to identify oil/source rock relationships. An analytical program was developed to

• Determine the nature and distribution of different oil families
• Evaluate source rock quality of different stratigraphic units
• Correlate oils with their source rocks. In the conclusions section of this report, results of the study are presented in terms of their exploration significance.

The results of this study are presented in an interpretive report as well as in three analytical data volumes and a data CDR.