Fossil overpressures compartments? A case study from the Eifel area and some general aspects

Fluid overpressures are well known from hydrocarbon exploration in many sedimentary basins. They can reach almost lithostatic values, and may cause the fracturing of rock. Fracturing allows the discharge of fluid overpressure, and fluid flows along a hydraulic gradient towards a low pressure reservoir. Different mechanisms may cause the precipitation from the fluid, such as a fluid pressure drop, a variation of temperature at the low pressure reservoir, or a different rock type inducing different Eh-pH conditions. Such precipitates in fractures are called veins, which often display paleo-fluid overpressures in rocks. In this study, we present some results from Devonian clastic sedimentary rocks of the Eifel area. Results are compared with other sedimentary basins to highlight some general aspects.conferenc

Changes in fluid pathways in a calcite vein mesh (Natih Formation, Oman Mountains): Insights from stable isotopes

We present a structural, microstructural, and stable isotope study of a calcite vein mesh within the Cretaceous Natih Formation in the Oman Mountains to explore changes in fluid pathways during vein formation. Stage 1 veins form a mesh of steeply dippin

Clay smear: Review of mechanisms and applications

AbstractClay smear is a collection of fault processes and resulting fault structures that form when normal faults deform layered sedimentary sections. These elusive structures have attracted deep interest from researchers interested in subsurface fluid flow, particularly in the oil and gas industry. In the four decades since the association between clay-smear structures and oil and gas accumulations was introduced, there has been extensive research into the fault processes that create clay smear and the resulting effects of that clay smear on fluid flow. We undertake a critical review of the literature associated with outcrop studies, laboratory and numerical modeling, and subsurface field studies of clay smear and propose a comprehensive summary that encompasses all of these elements. Important fault processes that contribute to clay smear are defined in the context of the ratio of rock strength and in situ effective stresses, the geometric evolution of fault systems, and the composition of the faulted section. We find that although there has been progress in all avenues pursued, progress has been uneven, and the processes that disrupt clay smears are mostly overlooked. We highlight those research areas that we think will yield the greatest benefit and suggest that taking these emerging results within a more process-based framework presented here will lead to a new generation of clay smear models

Kinematics of Crystal Growth in Single‐Seal Syntaxial Veins in Limestone ‐ A Phase‐Field Study

Building on recent developments in phase-field modeling of structural diagenesis, we present an analysis of single-seal syntaxial calcite vein microstructure in a variety of limestones. We focus on the effects of fracture aperture, intergranular versus transgranular fracturing, crystal habit and the presence of second phases in the host rock, to systematically investigate a simplified set of models covering the main classes of limestone in 2D. We incorporate the kinematic process of growth competition between differently oriented crystals, growth rate anisotropy between rough and faceted crystal surfaces and different growth rates on intergranular to transgranular fractures. Results show that within the considered parameter space we can reproduce a wide range of vein microstructures in limestone known in nature, such as stretched crystals, wide-blocky veins, and elongated crystals. We identify five archetypes of vein microstructures in limestones, which are diagnostic for different kinematics and evolution of transport processes and illustrate the effect of key parameters in microstructure maps. We show how syntaxial veins with median line form after intergranular fracturing, while stretched crystals indicate transgranular fracturing. Intergranular fracturing leads to stronger growth competition and more prominent CPO in syntaxial veins. Our results can be extended to 3D to include multiple crack-seal events, pore-space cementation and simulation of fluid flow, providing a generic platform for modeling structural diagenesis in limestones

Электроосаждение сплава свинец-олово из метансульфонатных растворов

Досліджено вплив різних чинників на склад сплаву свинець-олово, що осаджений з електроліту на основі метансульфонатної кислоти. Методом повного факторного експерименту ПФЕ2³ отримані рівняння регресії, що адекватно описують залежність вмісту олова в сплаві від умов осадження з електролітів із органічними добавками і без них.Effect of different factors on content of lead-tin alloys obtained from an electrolyte on the base of methanesulfonic acid is investigated. The method of full factor experiment FFE 2³ is used for obtaining of regression equations which adequately describe the relation between the electrodeposition condition and the contents of tin in alloys from electrolytes with and without some organic additives

Analisis Integrasi Padi Ikan Dalam Perspektif Agro Ekonomi

This study aimed to obtain information integration rice fish viewed from the perspective of agroeconomics. This study is motivated by the growth rate of rice production which likely to decline, decline in soil fertility due to continuous intensification. The method used was a survey method by taking the case of rice - fish farming in Solokan Jeruk District Bandung Regency West Java Province. Purposive sampling is used in this research. The expected benefit is to increase rice production, fish seed supply, income and welfare of farmers and the development of efficient utilization of paddy fields. The results showed the integration of fish rice as seen as agro-economic was positively gave the benefit for both farmers and for agricultural land itself. Keywords: rice, agro-econom

Petrophysical characterization, BIB-SEM imaging, and permeability models of tight carbonates from the Upper Jurassic (Malm ß), SE Germany

Tight carbonate rocks are important hydrocarbon and potential geothermal reservoirs, for example, in CO2-Enhanced Geothermal Systems. We report a study of outcrop samples of tectonically undeformed tight carbonates from the upper Jurassic “Malm ß” formation in Southern Germany near the town of Simmelsdorf (38 km NE of Nuremberg) to understand bulk petrophysical properties in relation to microstructure and to compare models for permeability prediction in these samples. We applied Archimedes isopropanol immersion, Helium pycnometry, mercury injection, gamma density core logging, and gas permeability measurements, combined with microstructural investigations and liquid metal injection (LMI-BIB-SEM). In addition, ultrasonic velocity was measured to allow geomechanical comparison of stratigraphically equivalent rocks in the South German Molasse Basin (SGMB). Results show only small variations, showing that the formation is rather homogeneous with bulk porosities below 5% and argon permeabilities around 1.4E−17 m2. The presence of stylolites in some of the samples has neither a significant effect on porosity nor permeability. Pores are of submicron size with pore throats around 10 nm and connected as shown by Mercury injection and Liquid Metal injection. Samples have high dynamic Young’s Modulus of 73 ± 5 GPa as expected for lithified and diagenetically overmature limestones. Moreover, no trends in properties were observable toward the faults at meter scale, suggesting that faulting was post-diagenetic and that the matrix permeabilities were too low for intensive post-diagenetic fluid–rock interaction. Petrophysical properties are very close to those measured in the SGMB, illustrating the widespread homogeneity of these rocks and justifying the quarry as a reasonable reservoir analog. Permeability prediction models, such as the percolation theory-based Katz-Thompson Model, Poiseuille-based models, like the Winland, the Dastidar, the capillary tube, and the Kozeny-Carman Models, as well as several empirical models, namely, the Bohnsack, the Saki, and the GPPT Models, were applied. It is shown that the capillary tube Model and the Saki Model are best suited for permeability predictions from BIB-SEM and mercury injection capillary pressure results, respectively, providing a method to estimate permeability in the subsurface from drill cuttings. Matrix permeability is primarily controlled by the pore (throat) diameters rather than by the effective porosity

Salt Creep: Transition Between the Low and High Stress Domains

In 2014–2016, creep tests were performed in a dead-end drift of the Altaussee mine, where temperature and relative humidity experience very small fluctuations. These tests, which were several months long, proved that the creep rate of a natural salt sample is much faster in the 0.2–1 MPa deviatoric stress range than the creep rate extrapolated from standard laboratory creep tests performed in the 5–20 MPa range. In addition, the quasi-steady strain rate is a linear function of stress, and it is faster when grain size is smaller. These findings were consistent with microphysical models of pressure solution creep (rather than dislocation creep, which is the governing creep mechanism at high stresses). A gap in experimental data remained in the 1–5 MPa range, calling for a follow-up experimental program. In 2016–2019, three multi-stage creep tests were performed on salt samples from Hauterives (France), Avery Island (Louisiana, USA), and Gorleben (Germany), which had been tested in the 0.2–1 MPa range during the 2014–2016 campaign. Loads of 1.5, 3, and 4.5 MPa were applied successively on each sample for 8 months. Steady state was not reached at the end of each 8-month stage. However, tests results suggest that, in the 0.2–3 MPa range, the relationship between the strain rate and the applied stress is linear, a characteristic feature of pressure solution. For these three samples, the relationship between strain rate and deviatoric stress departs from linearity when the deviator is larger than approximately 3–4.5 MPa, pointing to a transition to dislocation creep at higher deviatoric levels