Deep Drilling to Decipher Potential Interaction Between Shallow and Deep Fluid Systems: Preliminary Results From the INFLUINS Drilling Campaign in the Thuringian Basin, Central Germany

Abstract:

To shed light on the coupled dynamics of near surface and deep fluid systems in a sedimentary basin on various scales, ranging from the pore scale to the extent of an entire basin, is the overall goal of INFLUINS (INtegrated FLuid dynamics IN Sedimentary basins). To do so is essential to understand the functioning of sedimentary basins fluid systems. An integral INFLUINS topic also is the potential interaction of aquifers within a basin and at its rims.

Regionally, INFLUINS is focusing on the Thuringian basin, a well-confined, intra-continental sedimentary basin in central Germany as a natural geo-laboratory. The Thuringian basin is composed of sedimentary rocks from the latest Paleozoic and mainly Triassic and particularly suited to undertake such research as it is of relative small size, about 50 times 100 km, easily accessible, and quite well known from previous studies. INFLUINS consists on several projects tightly connected to each other and coming from various disciplines of geosciences including among others geophysics, hydrogeology, sedimentology, mineralogy, and remote sensing. A deep drilling campaign, which took place close to Erfurt in the center of the basin in summer 2013, is one of the main achievements of INFLUINS.

In preparation for deep drilling, in 2011, we conducted an extensive seismic reflection site survey, in the framework of which the center of the basin down to the top basement was imaged in high quality. Drilling went down to a depth of 1179 m, drilling Triassic rocks from Keuper to lower Buntsandstein and led to more than 500 m of cores of excellent quality and more than 600 cuttings samples. Down-hole geophysical logging over the entire depth of the drill hole is complemented with Multi Sensor Core Logging leading to an extensive geophysical data set with a spatial resolution up to the cm-scale.

Here, we present overall results of the drilling campaign and focus on the boundaries between major groups as well as between prominent beds including e.g. rock salt and other pronounced aquitards.