Empirical relations of rock properties of outcrop and core samples from the Northwest German Basin for geothermal drilling
Reyer, D.
Philipp, S. L.
2, 1: 21 - 37
DOI: https://doi.org/10.5194/gtes-2-21-2014
Persistent URL: http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/6861
Persistent URL: http://resolver.sub.uni-goettingen.de/purl?gldocs-11858/6861
Reyer, D.; Philipp, S. L., 2014: Empirical relations of rock properties of outcrop and core samples from the Northwest German Basin for geothermal drilling. In: Geothermal Energy Science, Band 2, 1: 21 - 37, DOI: 10.5194/gtes-2-21-2014.
|
View/
|
Information about geomechanical and physical rock properties, particularly uniaxial compressive
strength (UCS), are needed for geomechanical model development and updating with logging-while-drilling
methods to minimise costs and risks of the drilling process. The following parameters with importance at different
stages of geothermal exploitation and drilling are presented for typical sedimentary and volcanic rocks of
the Northwest German Basin (NWGB): physical (P wave velocities, porosity, and bulk and grain density) and
geomechanical parameters (UCS, static Young’s modulus, destruction work and indirect tensile strength both
perpendicular and parallel to bedding) for 35 rock samples from quarries and 14 core samples of sandstones and
carbonate rocks.
With regression analyses (linear- and non-linear) empirical relations are developed to predict UCS values
from all other parameters. Analyses focus on sedimentary rocks and were repeated separately for clastic rock
samples or carbonate rock samples as well as for outcrop samples or core samples. Empirical relations have high
statistical significance for Young’s modulus, tensile strength and destruction work; for physical properties, there
is a wider scatter of data and prediction of UCS is less precise. For most relations, properties of core samples plot
within the scatter of outcrop samples and lie within the 90% prediction bands of developed regression functions.
The results indicate the applicability of empirical relations that are based on outcrop data on questions related to
drilling operations when the database contains a sufficient number of samples with varying rock properties. The
presented equations may help to predict UCS values for sedimentary rocks at depth, and thus develop suitable
geomechanical models for the adaptation of the drilling strategy on rock mechanical conditions in the NWGB.
Statistik:
View StatisticsCollection
- Geologie [930]