Numerical Calculation of NMR Response for the 3D Digital Core Constructed with CT Images of the Tight Rock

2015 ◽  
Vol 719-720 ◽  
pp. 1089-1092 ◽  
Author(s):  
Yuan Zhong Zhang ◽  
Bao Lei Zhang
Keyword(s):  
Monte Carlo ◽  
Pore Space ◽  
Nmr Relaxation ◽  
Ct Images ◽  
Monte Carlo Algorithm ◽  
Tight Sandstone ◽  
Pore Connectivity ◽  
Digital Core ◽  
Monte Carlo Random Walk ◽  
Pulse Echo

The tight rock often has low porosity, low permeability and poor pore connectivity, which it is difficult for formation evaluation. Nuclear Magnetic Resonance (NMR) logging is widely used in fluid typing and reservoir parameters determination to provide the information of porosity, permeability and pore size distribution. NMR relaxation mechanisms are characterized by the pore-scale petrophysical models. Monte Carlo algorithm describes the Brownian motion of fluid molecules in pore space. In the paper we setup a 3D digital core of the tight sandstone with X-ray computer tomography (CT) images to model NMR response with Monte Carlo random walk algorithm. We compared T2 distributions from the numerical calculated pulse echo trains from the measurements. The results show that the simulated NMR response is consisted with the experiment.

scholarly journals Effects of Pore Connectivity on the Sorption of Fluids in Nanoporous Material: Ethane and CO2 Sorption in Silicalite

2021 ◽  
Vol 5 (3) ◽  
pp. 55
Author(s):  
Siddharth Gautam ◽  
David R. Cole
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Pore Space ◽  
Gas Storage ◽  
Nanoporous Materials ◽  
Nanoporous Material ◽  
Pore Connectivity ◽  
Guest Molecules ◽  
Adsorption Sites ◽  
Co2 Sorption

Adsorption of fluids in nanoporous materials is important for several applications including gas storage and catalysis. The pore network in natural, as well as engineered, materials can exhibit different degrees of connectivity between pores. While this might have important implications for the sorption of fluids, the effects of pore connectivity are seldom addressed in the studies of fluid sorption. We have carried out Monte Carlo simulations of the sorption of ethane and CO2 in silicalite, a nanoporous material characterized by sub-nanometer pores of different geometries (straight and zigzag channel like pores), with varied degrees of pore connectivity. The variation in pore connectivity is achieved by selectively blocking some pores by loading them with methane molecules that are treated as a part of the rigid nanoporous matrix in the simulations. Normalized to the pore space available for adsorption, the magnitude of sorption increases with a decrease in pore connectivity. The increased adsorption in the systems where pore connections are removed by blocking them is because of additional, albeit weaker, adsorption sites provided by the blocker molecules. By selectively blocking all straight or zigzag channels, we find differences in the absorption behavior of guest molecules in these channels.

Examining sharp restart in a Monte Carlo method for the linearized Poisson–Boltzmann equation

2020 ◽  
Vol 26 (3) ◽  
pp. 223-244
Author(s):  
W. John Thrasher ◽  
Michael Mascagni
Keyword(s):  
Monte Carlo ◽  
Free Energy ◽  
Monte Carlo Algorithm ◽  
Significant Bias ◽  
Poisson Boltzmann ◽  
Electrostatic Free Energy ◽  
Poisson Boltzmann Equation ◽  
The Stability ◽  
Potential Methods ◽  
The Individual

AbstractIt has been shown that when using a Monte Carlo algorithm to estimate the electrostatic free energy of a biomolecule in a solution, individual random walks can become entrapped in the geometry. We examine a proposed solution, using a sharp restart during the Walk-on-Subdomains step, in more detail. We show that the point at which this solution introduces significant bias is related to properties intrinsic to the molecule being examined. We also examine two potential methods of generating a sharp restart point and show that they both cause no significant bias in the examined molecules and increase the stability of the run times of the individual walks.

Adsorption of non-ionic surfactants on organoclays in drilling fluid investigated by molecular descriptors and Monte Carlo random walk simulations

2021 ◽  
Vol 538 ◽  
pp. 148154
Author(s):  
Dina Kania ◽  
Robiah Yunus ◽  
Rozita Omar ◽  
Suraya Abdul Rashid ◽  
Badrul Mohamed Jan ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Random Walk ◽  
Molecular Descriptors ◽  
Drilling Fluid ◽  
Ionic Surfactants ◽  
Monte Carlo Random Walk
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