Exploration for deep Paleozoic sediments in Uzbekistan using MT: Project ``Paleorift'

Abstract

To maintain self-sufficiency in oil, Uzbekistan is systematically exploring all oil-prospective basins in the country, including the Bukharo-Khivinsky paleorift (BKP) in central Uzbekistan. The BKP has a prospective area of 14 100 km2 and contains an estimated 63 000 km3 of prospective Paleozoic sediments below gas-producing Mesozoic sediments. The ``Paleorift' project (begun in November 2001) is an integrated project comprising ten regional profiles 80?90 km long that will include seismic (using new 3D equipment), MT, gravity, magnetics, and thermometry. The field work began with MT because MT costs less than seismic, is easy and quick to use and interpret, causes minimal disturbance to agricultural land, and is definitive in this application. Uzbekneftegaz has long experience with MT and other electrical methods and routinely uses them before seismic. Approx. 350 MT stations were measured on three of the regional profiles (1 km station spacing) and on two ``prospecting' profiles (500 m station spacing) over known Mesozoic gas deposits. The profiles mapped the boundaries of the BKP central graben, a crustal conductor in the north part of the BKP, a gas-producing Jurassic structural high, and a resistivity low associated with the gas deposits.