SECONDARY CARBONATES OF JURASSIC SAND DEPOSITS AS INDICATORS OF THE PALEOZOIC PRODUCTIVITY

Abstract

This work is based on the concept of deep genesis of fluids, followed by subvertical migration (from the bottom up) through permeable zones and unloading in overlying reservoirs. Moreover, geochemical transformations of allogenic minerals occur in the discharge zones and on the fluid migration routes. The intensities of secondary, superimposed-epigenetic formation of minerals depend on liquid physical and chemical properties and its flow velocity. The aim of the article is to show the relation between the intensity of secondary carbonation of Jurassic sand deposits and the nature of saturation of the Paleozoic rocks. The intensity of secondary carbonation was determined using advanced technology of statistical logging interpretation. The results of the intensities were compared with the results of lithologic-petrographic, mineralogical studies of the core-samples and with the results of the Paleozoic collectors tests. The relevance of this research is associated with the opportunity to identify the location of oil and gas deposits in the bottom of layer based on the results of statistical interpretation of production logging data in Jurassic sediments, using the materials of the old Fund. The object of the research is the Jurassic sand layers at the Gerasimovskoe field (Tomsk Region). When the intensity of Jurassic layer carbonation grows the probability of detection of oil-saturated deposits increases too. From the perspective of identifying the Paleozoic productive deposits, the authigene siderite is the most informative carbon-bearing mineral in the Jurassic sediments.

Keywords

• well logging
• the paleozoic oil-and-gas content
• secondary carbonates
• fluid depth migration
• gerasimovskoe field