Petrophysical features of the ore-bearing Eldzhurtinsky massif (northern Caucasus)

Abstract

The Eldzhurtinsky granite massif was formed during the Late Alpine tectono-magmatic activity. The molybdenum-tungsten deposit is associated with it spatially and paragenetically. Under the ultradeep drilling programme, wells to a depth of 4695 m are drilled into the massif. Comprehensive petrophysical studies were conducted on the basis of cores from four of the wells; the vertical (No. 600, 104, 1500) and horizontal (No. 1393) have made it possible to reveal the petrophysical characteristics of the intrusion in the vertical plan in the 3300 × 1100 m cross-section. Altogether, 72 samples have been studied. In keeping with the technique worked out at the Geological Faculty of Moscow University, the following properties were determined: density, porosity, saturation parameters and elastic parameters; and velocities of longitudinal and transverse ultrasound waves, Poisson coefficients, shear and Young's moduli and piezoelectric characteristics. Debye temperature and the comprehensive petrophysical coefficient were calculated. Petrophysical zonality was detected in the vertical cross-section of the massif in the direction from top to bottom. From the physical-mechanical properties and the character of multi-dimensional correlation between various properties, the investigated cross-section of the massif can be divided into three zones: the upper, the middle and the lower.