scholarly journals Transport of a two-member decay chain in a single fracture: Simplified analytical solution for two radionuclides with the same transport properties

2000 ◽  
Vol 36 (5) ◽  
pp. 1339-1346 ◽  
Author(s):  
J. Cormenzana
Keyword(s):  
Analytical Solution ◽  
Transport Properties ◽  
Decay Chain ◽  
Single Fracture

Effective Flow Properties for Cells Containing Fractures of Arbitrary Geometry

SPE Journal ◽  
2016 ◽  
Vol 21 (03) ◽  
pp. 0965-0980 ◽  
Author(s):  
A.. Sakhaee-Pour ◽  
Mary F. Wheeler
Keyword(s):  
Transport Properties ◽  
Cell Model ◽  
Petroleum Industry ◽  
Spatial Location ◽  
Effective Porosity ◽  
Single Fracture ◽  
Fracture Geometry ◽  
Hydrocarbon Production ◽  
Flow Models ◽  
Matrix Permeability

Summary Hydrocarbon production from unconventional resources such as shale usually entails stimulation by hydraulic fracturing, which results in nonplanar (curved) fractures. However, most reservoir models assume that the induced fractures are planar for the sake of simplicity. Considering the growing interest of the petroleum industry in better understanding production from these resources, we develop a fracture-cell model to capture the effects of fracture nonplanarity on transport properties. To build a realistic reservoir model for a fractured formation, we must account for three types of interactions: matrix-matrix (M-M), matrix-fracture (M-F), and fracture-fracture (F-F). The transport properties of the M-M interaction are based on laboratory measurements. In this study, we analytically determine the transport properties of the two other types of interactions (M-F and F-F). For this purpose, we account for the aperture size and spatial location of the fracture. As a result, we provide effective porosity and effective anisotropic permeabilities for a reservoir cell that contains a fracture inside it. The reservoir cell with transport properties that are modified is a fracture cell. We implement the fracture-cell model in a reservoir simulator and perform analyses for a single fracture and for multiple intersecting fractures; these fractures are nonplanar. The analyses include both single- and multiphase flow models and show that the hydrocarbon pressure inside the reservoir is strongly dependent on the fracture geometry when the matrix permeability is smaller than 1 µd. Thus, it is crucial to model the fracture geometry more accurately in unconventional reservoirs with ultralow permeabilities such as shale. One can easily implement the developed fracture-cell model in reservoir simulators, and there is no local refinement around the fracture. The main advantage of the proposed model is its simplicity, conjoined with its ability to capture the nonplanarity of the fracture. The developed model has major applications for understanding production from formations that are heavily fractured.

Development of tools for studying contaminant transport in fractured rock environment: laboratory migration experiments in physical models with artificial and natural fractures

2020 ◽  
Author(s):  
Filip Jankovský ◽  
Václava Havlová ◽  
Milan Zuna ◽  
Petr Polívka ◽  
Jakub Jankovec ◽  
...  
Keyword(s):  
Transport Properties ◽  
Laser Scanning ◽  
Large Scale ◽  
Breakthrough Curves ◽  
Physical Models ◽  
Low Flow ◽  
Single Fracture ◽  
Natural Fractures ◽  
Line Measurement ◽  
Migration Pathways

<p>Migration of contaminants (radionuclides, heavy metals, nanoparticles) in crystalline rock environment is driven mainly by advective processes in fractures. The main goal of our project is to develop tools for evaluation of migration and retention of potential contaminants in the rock environment. Since the naturally fractured environment is typically too complex to describe, it is common to mimic its behaviour by means of numerically simulated fracture network. The groundwork for applicable simulation of large-scale structures comes out from comprehension and verification of parameters for basic components such as a single fracture. For this reason, number of numerical simulations were performed to evaluate hydraulic and transport properties of an artificial and natural single fracture system by means of different modelling approaches. This will be presented in details in a separate conference contribution by Hokr et al.</p><p>Two granite blocks were split and reassembled to generate physical models with artificial fractures. Significant contribution to the exact model representation of the flow regime is the precise fracture topography description, derived from the method of the laser scanning. This allows the model resolution up to 100 µm for each of the two granite blocks used in the study and subsequently the identification of the preferential pathways of the contaminant spreading. Both blocks were customized for both on-line measurement of the selected parameters and sample collection for off-line measurement. This arrangement allowed us to perform series of migration experiments with different conservative (NaCl, KCl, KI, HTO) and sorbing (Pb(ClO<sub>4</sub>)<sub>2</sub>) tracers. The focus of the numerical modelling effort is to fully describe the hydraulic and transport properties of the fractured granite environment based on the data from experimental tracer tests. Pressure field distribution across the fracture and breakthrough curves at the sampled positions were used for the fracture parameters calibration and evaluation of the model overall reliability.</p><p>Several physical models with natural fractures were prepared from suitable sections of borehole cores coming from two locations in the Czech Republic (underground research center Bukov and Mrákotín quarry). Data from transmissivity measurements and conservative tracer breakthrough curves served as initial parameters for fracture description. Specially designed experimental set-up for conducting of migration experiments with very low flow rate was applied. Moreover in collaboration with HZDR (Leipzig, Germany) the unique combination of PET – µCT techniques was employed. Spatiotemporal images of the radioactive tracer (<sup>18</sup>F) concentration during conservative transport were recorded with positron emission tomography (GeoPET), and the underlying fracture structure was characterized by µCT-imaging. First results are proving the existence of preferential migration pathways within the studied natural fractures.</p><p>The activities were funded by Czech Technological Agency under Project No. TH02030543</p>

Analytical solution to the diffusion, sorption and decay chain equation in a saturated porous medium between two reservoirs

2015 ◽  
Vol 139 ◽  
pp. 163-170
Author(s):  
Juan Guzman ◽  
Serguei Maximov ◽  
Rafael Escarela-Perez ◽  
Irvin López-García ◽  
Mario Moranchel
Keyword(s):  
Porous Medium ◽  
Analytical Solution ◽  
Saturated Porous Medium ◽  
Decay Chain ◽  
Chain Equation
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