MIGRATION TESTS IN FISSURED-POROUS CARBONATE ROCKS OF THE OIL-SHALE DEPOSIT OF THE ESTONIAN FIELD

Field experiments are acknowledged as the basic methods in determining migration parameters in fissured-porous rocks. The paper presents the results of migration tests conducted within the peripheral part of the Vasavere buried valley (Fig. 1). Migration tests have been carried out within the water-bearing strata of the Ordovician carbonate rocks 20 m in thickness, separated from the bed of Quaternary sediments by a 1.4-m-thick loam layer. By means of geophysical research technique (flowmetry and resistivimetry) the presence of two fractured permeable zones at the depth intervals of 19.5-20.3 m and 18.8-19.1 m in this carbonate stratum has been detected. In the course of the experiments a pulse injection of traces, such as chloride ions and fluorescein, into the observation wells of the multiwell system was carried out and specific sampling of the Ordivician carbonate stratum conducted using the method of doublets (Figs. 2-6; Table). The numerical values of the migration parameters obtained through migration tests, and recommended for the use in the forecast calculating schemes are as follows: the coefficient of fracturing is (0.5-1.0) . 10(-3), the complex parameter of mass transport - 4.2 . 10(-3) day-1.