--> Abstract: Evaluating and Mapping Seals from Geophysical Data Methods, by Khitrov and Savinkin; #90942 (1997).

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Abstract: Evaluating and Mapping Seals from Geophysical Data Methods

KHITROV, and SAVINKIN

The main idea of our approach is that the oil-water (gas-water) contact is controlled by the spill point which belongs not to the top surface of the reservoir, but to the sole of the genuine seal at the critical degree of the local structure. Usually there are beds between the top surface of the reservoir and the genuine seal; they are neither reservoirs nor seals. These beds form a so-called "false" seal.

The genuine and false seals could be detected from well-logging data by using interpretation technique. Genuine seals usually are formed by beds which have no signs of oil and gas at any point of these beds inside the local structure. There are no signs of the permeability at any points of these beds too. False seals are the totality of the beds with the low (but not equal to zero) permeability. Very often these beds have the signs of oil and gas which could be identified from well logs and core example.

The technique for detecting and mapping genuine and "false" seals from logs and seismic in oil exploration was applied to decrease the number of water wells during 1984-1993 years in the Timan-Pechora basin, the Volga-Urals, Western Siberia, Uzbekistan and Kazakhstan, in China (Tarim basin).

For example, the accuracy predictions were made for the Upper Devonian and Lower Permian reefs in Khoreiver depression and Kolvinski megaval, where 52 out of 55 wells drilled confirmed the predictions. Since 1986, after the first test of the predictions by drilling, the authors consulted "Arhangelskgeologia" every year.

Today, after 9 years of the utilization of this technique we can state that the confirmation of the predictions of productive and non-productive reservoirs amount to 80-90%.

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