Scholarly record

GEOPHYSICAL AND GEOLOGICAL INVESTIGATIONS OF THE LATE JURASSIC - EARLY CRETACEOUS AQUIFER IN CERNAVODA AREA, SOUTH DOBROGEA (ROMANIA)

Bogdan Mihai Niculescu

Abstract

Carbonate reservoirs are important exploration targets from the perspective of hydrocarbon and, also, groundwater reserves. In this respect, the most important aquifer system in Romania is located in South Dobrogea region, comprising two distinct aquifer complexes: a deeper one, mostly under pressure, hosted in fractured/fissured and karstified limestones and dolomites of Late Jurassic - Early Cretaceous age and a shallower one, mostly unconfined, hosted in Sarmatian (late Middle Miocene) lumachellic and oolitic limestones. The deeper aquifer is regional, confined on more than 60% of its extension, has a SW-NE general flow direction and discharges in Siutghiol Lake (Constan?a city area) and through submarine springs on the Black Sea continental shelf. The water flow occurs through fractures/fissures and dissolution voids within the carbonate rocks and, also, along fault planes. Although a large number of wells were drilled in South Dobrogea for groundwater exploitation from the Late Jurassic - Early Cretaceous aquifer and, also, for groundwater quality monitoring, there are few published data and studies regarding the geophysical response and petrophysical features of these formations, in relation with their hydrogeological characteristics. The more recent drilling of three hydrogeological research boreholes in the proximity of Cernavod? Nuclear Power Plant (NPP) offered an opportunity to gain valuable information concerning the geological succession in this northern part of South Dobrogea, with special regard to the carbonate formations hosting the aquifer. The boreholes were drilled to a depth of 700 m, for the identification and exploitation of aquifer horizons, in order to provide a fresh water supply for the NPP units. Geological analyses on drill cuttings and cores and geophysical well logging were carried out, for a comprehensive characterization of the intercepted formations from a lithologic and stratigraphic viewpoint, the identification of fractures/fissures and caverns as potential water-producing zones and the evaluation of formation porosity. The geophysical logs interpretation showed that the most probable water-producing zones are located in the so-called dolomitic complex (Kimmeridgian ? Tithonian) on the 620 ? 700 m (particularly 650 ? 700 m) depth interval, in carbonates with average porosities of 12 ? 16% and locally reaching more than 40%.

Publication Impact Profile

• Citations
• CrossRef - Citation Indexes: 1
• Policy Citation - Policy Citations: 4
• Scopus - Citation Indexes: 2

• Captures
• Mendeley - Readers: 3

PLUMX see details

DOI resolver: doi.org/10.5593/sgem2018/1.1/s05.103

Publication details

Back to publication list