--> Abstract: Localization of Shallow Gas Deposits and Uncontrolled Gas Flows in Young and Unconsolidated Sediments by Geophysical Methods, by J. Csorgei, I. Kummer, A. Papa, J. Sipos, I. Solyom, E. Takacs, Z. Timar, and T. Keresztes; #90990 (1993).

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CSORGEI, J., I. KUMMER*, A. PAPA, J. SIPOS, I. SOLYOM, E. TAKACS, and Z. TIMAR, Eotvos Lorand Geophysical Institute of Hungary, Budapest, Hungary, and T. KERESZTES, MOL RT, Budapest, Hungary

ABSTRACT: Localization of Shallow Gas Deposits and Uncontrolled Gas Flows in Young and Unconsolidated Sediments by Geophysical Methods

The great mass of Neogene sediments in the Hungarian basin, where several hydrocarbon accumulations are known, is affected by Pliocene strike-slip movements, resulting in a lot of "flower structures." The gas may migrate from the reservoirs upward to the surface along the faults. Thus, shallow gas deposits can be located in the young, unconsolidated sands. There are also several shallow gas deposits derived from uncontrolled gas flows.

In Hungary, the shallow gas reservoirs, being not too large, have not yet been explored properly. Their importance, however, has recently increased. However, the depleting gas may pollute

the water in the soil, as well as cause explosions.

Our purpose is to develop inexpensive, complete, and highly sophisticated field- and data-processing techniques, and an integrated complex of geophysical methods, in order to define the limits of shallow gas deposits.

To avoid anomalous behavior on seismic sections of the depleting gas, we started from uncontrolled gas flows, which requires special velocity and amplitude vs. offset analyses. In addition, natural and controlled source electromagnetic/electric survey of various parameters were applied.

The poster presents an industrial-scale seismic section over an uncontrolled gas flow, special sections over flower structures and geoelectric sections, and a magnetic map.

The integrated complex of geophysical methods outlined above is under development to establish the conditions of the exploration of gas reservoirs that have been used close to their locality, and they could be recovered with little expense.

AAPG Search and Discovery Article #90990©1993 AAPG International Conference and Exhibition, The Hague, Netherlands, October 17-20, 1993.