Dilatant shear band formation and diagenesis in calcareous, arkosic sandstones, Vienna Basin (Austria)

Abstract

The present study examines deformation bands in calcareous arkosic sands. The investigated units can be considered as an equivalent to the Matzen field in the Vienna Basin (Austria), which is one of the most productive oil reservoirs in central Europe. The outcrop exposes carbonate-free and carbonatic sediments of Badenian age separated by a normal fault. Carbonatic sediments in the hanging wall of the normal fault develop dilation bands with minor shear displacements (< 2 mm), whereas carbonate-free sediments in the footwall develop cataclastic shear bands with up to 70 cm displacement. The cataclastic shear bands show a permeability reduction up to 3 orders of magnitude and strong baffling effects in the vadose zone. Carbonatic dilation bands show a permeability reduction of 1-2 orders of magnitude and no baffling structures. We distinguished two types of deformation bands in the carbonatic units, which differ in deformation mechanisms, distribution and composition. Full-cemented bands form as dilation bands with an intense synkinematic calcite cementation, whereas the younger loose-cemented bands are dilatant shear bands cemented by patchy calcite and clay minerals. All analyzed bands are characterized by a porosity and permeability reduction caused by grain fracturing and cementation. The changed petrophysical properties and especially the porosity evolution are closely related to diagenetic processes driven by varying pore fluids in different diagenetic environments. The deformation band evolution and sealing capacity is controlled by the initial host rock composition.

Simulation of Fracturing and Well Pattern Optimization of Fractured Tight Sandstone Reservoirs

“…In addition, in order to more accurately and intuitively characterize the water flooding process in the well pattern and the effect of fracture seepage on the productivity of the fractured wells, the logarithmic grid refinement technology was used in the modeling. The use of this technique can not only describe the hydraulic fractures finely, but also avoid the problems of long calculation time and non-convergence of the Local Refinement Grid (LGR) method (Gurocak et al, 2012;Lommatzsch et al, 2015).…”

Evolution of deformation mechanism and fluid flow in two pre-rift siliciclastic deposits (Pannonian Basin, Hungary)

“…5B, C) in this type of bands (M-Fa, M-So) indicates that calcite precipitation favoured these structures. Carbonate cemented protocataclastic type bands were only described in a few places (Balsamo et al, 2012;Skurtveit et al, 2015;Lommatzsch et al, 2015b;Del Sole and Antonellini, 2019). The work of Lommatzsch et al (2015b) assumed that the massive cementation of DB preserved the early phase of dilation during band formation.…”

“…Although, deformation bands (DB) are ubiquitous structures in poorly lithified sediments, they were used for detailed diagenetic investigations only in limited cases (e.g. Eichhubl et al, 2004;Hodson et al, 2016;Balsamo et al, 2012;Lommatzsch et al, 2015aLommatzsch et al, , 2015bBeke et al, 2019). DBs can either behave as path (Balsamo et al, 2012;Beke et al, 2019) or barrier to fluid flow (Pittman, 1981;Antonellini and Aydin, 1994;Davatzes et al, 2003;Shipton et al, 2005;Torabi and Fossen, 2009;Ballas et al, 2012;Tueckmantel et al, 2012;Torabi et al, 2013;Rotevatn et al, 2013) depending on their deformation mechanism.…”

Staged Fracturing of Horizontal Wells in Continental Tight Sandstone Oil Reservoirs: A Case Study of Yanchang Formation in Western Ordos Basin, China

“…Fractured horizontal wells will produce a series of fracture networks including transverse fractures, axial fractures and horizontal fractures. The effect of hydraulic fracturing of horizontal wells is controlled by the geostress state in the tight oil reservoir and the fracturing construction measures (Li and Zhang, 1997;Liu et al, 2015;Lommatzsch et al, 2015;Li et al, 2018;Luo et al, 2018).…”