The Rock Model

2021 ◽  
pp. 11-63
Author(s):  
Mark Bentley ◽  
Philip Ringrose
Keyword(s):  
Author(s):  
Balint Penzes ◽  
Hoe-Chian Yeow ◽  
Peter Harris ◽  
Christopher Heap

2019 ◽  
Vol 7 (4) ◽  
pp. SJ1-SJ6 ◽  
Author(s):  
Liang Luo ◽  
Jiahong Jin ◽  
Wei Wei ◽  
Jianchao Cai

The microstructure of reservoir rocks plays an important role in oil and gas accumulation and production. We examine a universal method to evaluate these properties of rocks, such as pore tortuosity, matrix porosity, and connectivity, and we respectively construct a 2D numerical reconstruction rock model with different microstructure parameters by the Monte Carlo method and the quartet structure generation set method. We further study the heterogeneity (characterized by fractal dimension and tortuosity) of the constructed image for reservoir rocks by the numerical and theoretical analysis and obtain the formulas for fractal dimension and tortuosity versus porosity. The simulation results show that the logarithmic relation is between the pore fractal dimension and porosity, and the relationship between tortuosity and porosity has the form of power. This process provided an important method to advance 2D reconstruction technology of reservoir rocks and effectively determine the relationship between microstructure and porosity.


2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Zengwei Zhang ◽  
Fan Chen ◽  
Chao Zhang ◽  
Chao Wang ◽  
Tuo Wang ◽  
...  

A grain-based rock model was developed and applied to study mechanical characteristics and failure micromechanics in thick-walled cylinder and wellbore stability tests. The rock is represented as an assembly of tetrahedral blocks with bonded contacts. Material heterogeneity is modeled by varying the tensile strength at the block contacts. This grain-based rock model differs from previous disk/sphere particle-based rock models in its ability to represent a zero (or very low) initial porosity condition, as well as highly interlocked irregular block shapes that provide resistance to movement even after contact breakage. As a result, this model can reach higher uniaxial compressive strength to tensile strength ratios and larger friction coefficients than the disk/sphere particle-based rock model. The model captured the rock fragmentation process near the wellbore due to buckling and spalling. Thin fragments of rock similar to onion skins were produced, as observed in laboratory breakout experiments. The results suggest that this approach may be well suited to study the rock disaggregation process and other geomechanical problems in the rock excavation.


Author(s):  
Michel Pichavant ◽  
Tahar Hammouda ◽  
Bruno Scaillet

ABSTRACT:The current underlying assumption in most geochemical studies of granitic rocks is that granitic magmas reflect their source regions. However, the mechanisms by which source rocks control the intensive and compositional parameters of the magmas remain poorly known. Recent experimental data are used to evaluate the ‘source rock model’ and to discuss controls of (1) redox states and (2) the Sr isotopic compositions of granitic magmas.Experimental studies have been performed in parallel on biotite-muscovite and tourmaline-muscovite leucogranites from the High Himalayas. Results under reducing conditions ( = FMQ – 0·5) at 4 kbar and variable suggest that the tourmaline-muscovite granite evolved under progressively more oxidising conditions during crystallisation, up to values more than four log units above the FMQ buffer. Leucogranite magmas thus provide an example of the control of redox conditions by post-segregation rather than by partial melting processes.Other experiments designed to test the mechanisms of isotopic equilibration of Sr during partial melting of a model crustal assemblage show that kinetic factors can dominate the isotopic signature in the case of source rocks not previously homogenised during an earlier metamorphic event. The possibility is therefore raised that partial melts may not necessarily reflect the Sr isotopic composition of their sources, weakening in a fundamental way the source rock model.


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