Focused fluid-flow structures potentially caused by solitary porosity waves

Abstract

Gas chimneys, fluid-escape pipes, and diffused gas clouds are common geohazards above or below most petroleum reservoirs and in some CO2 storage sites. However, the processes driving the formation of such structures are poorly understood, as are the time scales associated with their growth or their role as long-term preferential fluid-migration pathways in sedimentary basins. We present results from a multidisciplinary study integrating advanced seismic processing techniques with high-resolution simulations of geological processes. Our analyses indicate that time-dependent rock (de)compaction yields ascending solitary porosity waves forming high-porosity and high-permeability vertical chimneys that will reach the surface. The size and location of chimneys depend on the reservoir topology and compaction length. Our simulation results suggest that chimneys in the studied area could have been formed and then lost their connection to the reservoir on a time scale of a few months.

Melt Migration and Chemical Differentiation by Reactive Porosity Waves

“…Porosity waves are an ubiquitous feature arising from the governing equations of compressible two-phase flow (e.g., McKenzie, 1984;Scott & Stevenson, 1984). Such waves have been observed in analogue experiments (e.g., Scott et al, 1986) and have been proposed as mechanism forming observed seismic chimneys above hydrocarbon reservoirs (e.g., Yarushina et al, 2021). Connolly and Podladchikov (1998) show that employing a visco-elastic volumetric deformation of the solid enables porosity waves to travel through rock in the limit of zero initial connected porosity.…”

Pipe Formation by Fluid Focalization in Bilayered Sediments

“…The challenge, therefore, is to obtain insights into their dynamics-either short or long term-to evaluate their risk potential [15]. To do so, many analogue experiments [16][17][18][19][20][21][22][23][24][25] and numerical models [4,13,22,[25][26][27][28] have been proposed in the literature (see also [29] for a complementary review). However, these models mostly consider a homogeneous sedimentary bed and scarcely account for its complex structure.…”

Microscopic Analysis of Natural Fracture Properties in Organic-Rich Continental Shale Oil Reservoirs: A Case Study from the Lower Jurassic in the Sichuan Basin, China

“…Natural fractures are the primary channels for oil and gas seepage, making them essential for enhanced recovery [23][24][25][26]. In addition, natural fractures in reservoirs are crucial for creating a low-carbon environment, as they serve as significant storage spaces for carbon storage [27][28][29][30][31][32]. Consequently, many scholars have conducted research on shale natural fractures [21,[33][34][35][36] and the multi-scale dimensional evaluation of natural fractures in shale has been a hot topic [22,37,38].…”