GEOLOGICAL AND GEOPHYSICAL STUDIES AND EXPLORATORY DRILLING OF PALEOZOIC SEDIMENTS IN THE TASBULAK GRABEN

Abstract

Despite the half-century history of prospecting, the geological and geophysical knowledge of the Shu-Sarysu basin does not exceed 50%. At the same time, the Tasbulak graben remains the most unstudied. From 1941 to 1969 Regional and exploratory aeromagnetic surveys using Z-aerial magnetometers and fluxgate magnetometers at scales of 1:500,000-1:100,000 covered the areas of the western, northwestern and partially central parts of the Shu-Sarysu depression. From 1969 to the present, up to 70% of the area of the Shu-Sarysu depression has been covered with high-precision surveys using proton, fluxgate and quantum aeromagnetometers on a scale of 1:50,000-1:25,000. In fact, the entire territory of the Shu-Sarysu depression is covered by areal gravimetric surveys on a scale of 1:200,000, scales of 1:50,000-1:100,000 - about 70-75% of the area. In the west and southeast of this depression, individual areas were worked out by detailed surveying on a scale of 1:25,000. Over the entire period of satellite surveys (from 1972 to the present), a significant archive of high, medium and low-resolution images has been accumulated. Seismic exploration of the territory of the Tasbulak graben using the CDP and CDP methods was carried out in the period from 1968 to 1993. Seismic exploration using the CDP - 3D method was not carried out. With a total area of the basin of more than 150 thousand square kilometers, the degree of its drilling exploration is extremely low (about 1 well per 375-475 square kilometers). The degree of study of the Tasbulak graben is even less. As a result of prospecting and exploration work, 12 gas and gas condensate deposits were identified, including: 6 in the Moyynkum graben, 3 in the Kokpansor graben and 3 on the Talas uplift (helium). The totality of geophysical work carried out within the Tasbulak graben indicates a premature cessation of oil and gas exploration in the region and the need for detailed work to verify the presence of more complex structures and their reservoir properties.