Control of Pore Types and Fracture Intensity on the P-Wave Velocity of Carbonate Rocks

2019 ◽  
Author(s):  
Ammar Abdlmutalib ◽  
Osman Abdullatif
Keyword(s):  
Wave Velocity ◽  
Carbonate Rocks ◽  
P Wave ◽  
P Wave Velocity ◽  
Fracture Intensity ◽  
Pore Types

scholarly journals Optimization of Rock Physics Models by Combining the Differential Effective Medium (DEM) and Adaptive Batzle-Wang Methods in “R” Field, East Java

2019 ◽  
Vol 17 (2) ◽  
Author(s):  
M. Wahdanadi Haidar ◽  
Reza Wardhana ◽  
M. Iskan ◽  
M. Syamsu Rosid
Keyword(s):  
Elastic Modulus ◽  
Wave Velocity ◽  
Carbonate Rocks ◽  
Effective Medium ◽  
Carbonate Reservoir ◽  
P Wave ◽  
S Wave ◽  
P Wave Velocity ◽  
Reservoir Conditions ◽  
Pore Types

The pore systems in carbonate reservoirs are more complex than the pore systems in clastic rocks. There are three types of pores in carbonate rocks: interparticle pores, stiff pores and cracks. The complexity of the pore types can lead to changes in the P-wave velocity by up to 40%, and carbonate reservoir characterization becomes difficult when the S-wave velocity is estimated using the dominant interparticle pore type only. In addition, the geometry of the pores affects the permeability of the reservoir. Therefore, when modelling the elastic modulus of the rock it is important to take into account the complexity of the pore types in carbonate rocks. The Differential Effective Medium (DEM) is a method for modelling the elastic modulus of the rock that takes into account the heterogeneity in the types of pores in carbonate rocks by adding pore-type inclusions little by little into the host material until the required proportion of the material is reached. In addition, the model is optimized by calculating the bulk modulus of the fluid filler porous rock under reservoir conditions using the Adaptive Batzle-Wang method. Once a fluid model has been constructed under reservoir conditions, the model is entered as input for the P-wave velocity model, which is then used to estimate the velocity of the S-wave and the proportion of primary and secondary pore types in the rock. Changes in the characteristics of the P-wave which are sensitive to the presence of fluid lead to improvements in the accuracy of the P-wave model, so the estimated S-wave velocity and the calculated ratio of primary and secondary pores in the reservoir are more reliable.

Pore-pressure prediction in carbonate rock using wavelet transformation

Geophysics ◽  
2014 ◽  
Vol 79 (4) ◽  
pp. D243-D252 ◽  
Author(s):  
Fu Yu ◽  
Yan Jin ◽  
Kang Ping Chen ◽  
Mian Chen
Keyword(s):  
Pore Pressure ◽  
Wave Velocity ◽  
Carbonate Rocks ◽  
Wavelet Transformation ◽  
Pressure Change ◽  
P Wave ◽  
Small Scale ◽  
Prediction Methods ◽  
P Wave Velocity ◽  
Pore Pressure Prediction

Accurate prediction of pore pressure can assist engineers to better work out and optimize an oilfield development plan. Because the P-wave velocity only experiences small-scale fluctuations for pore-pressure change in carbonate rocks, existing well-known pore-pressure prediction methods are incapable of predicting pore pressure in carbonate rocks with field-required accuracy. We evaluated a new method based on the P-wave velocity decomposition and wavelet transformation to predict pore pressure in carbonate rocks. The P-wave velocity was decomposed into contributions from the pore fluid and the rock framework using Biot’s theory. The effect of lithology, pore structure, porosity, and pore pressure on P-wave velocity was studied by theoretical analysis and experiments. Rapid triaxial rock-system tests were carried out to measure the P- and S-wave velocities when pore pressure, pore structure, and porosity were changed, and X-ray diffraction tests were used to measure mineral components. The small-scale fluctuations of the P-wave velocity can be extracted and amplified using wavelet transformation. We found that the small-scale fluctuations of the P-wave velocity were caused by pore-pressure change in carbonate rocks and the large-scale fluctuations of the P-wave velocity depended on the rock framework. Overpressure formation can be identified by the high-frequency detail of wavelet transformation of P-wave velocity. A pore-pressure prediction model relating the contribution from the pore fluid to the P-wave velocity was developed. This model is an improvement over existing pore-pressure prediction methods that mainly rely on empirical relations between the P-wave velocity and the pore pressure. This new method was successfully applied to carbonate rocks in Tazhong Block, Tarim oilfield, demonstrating the feasibility of the proposed pore-pressure prediction method.

Pore-scale modeling of elastic wave propagation in carbonate rocks

Geophysics ◽  
2015 ◽  
Vol 80 (1) ◽  
pp. D51-D63 ◽  
Author(s):  
Zizhen Wang ◽  
Ruihe Wang ◽  
Ralf J. Weger ◽  
Tianyang Li ◽  
Feifei Wang
Keyword(s):  
Porous Media ◽  
Wave Propagation ◽  
Elastic Wave ◽  
Pore Structure ◽  
Wave Velocity ◽  
Carbonate Rocks ◽  
P Wave ◽  
Pore Scale ◽  
Scale Modeling ◽  
P Wave Velocity

The relationship between P-wave velocity and porosity in carbonate rocks shows a high degree of variability due to the complexity of the pore structure. This variability introduces high uncertainties to seismic inversion, amplitude variation with offset analysis, porosity estimation, and pore-pressure prediction based on velocity data. Elastic wave propagation in porous media is numerically modeled on the pore scale to investigate the effects of pore structure on P-wave velocities in carbonate rocks. We built 2D models of porous media using pore structure information and the similarity principle. Then, we simulated normal incidence wave propagation using finite element analysis. Finally, the velocity was determined from received modeled signals by means of crosscorrelation. The repeatability and accuracy of this modeling process was verified carefully. Based on the modeling results, a simple formulation of Sun’s frame flexibility factor ([Formula: see text]), aspect ratio (AR, the ratio of the major axis to the minor axis), and pore density was developed. The numerical simulation results indicated that the P-wave velocity increases as a power function as the AR increases. Pores with small AR ([Formula: see text]) or large [Formula: see text] created softening effects that decrease P-wave velocity significantly. The P-wave velocity of carbonate rocks was dispersive; it depends on the ratio of the wavelength to pore size ([Formula: see text]). Such scale-dependent dispersion was more evident for carbonate rocks with higher porosity, lower AR, and/or lower P-wave impedance of pore fluids. The P-wave velocity of carbonate rocks with complicated pore geometries (low AR, high [Formula: see text], small [Formula: see text]) was much lower than that of rocks with simple pore geometries (high AR, small [Formula: see text], large [Formula: see text]) at low and high [Formula: see text]. The pore-scale modeling of elastic wave properties of porous rocks may explain the poor velocity-porosity correlation in carbonate rocks.

Permeability dependence of porosity and p-wave velocity in carbonate rocks

2016 ◽  
Author(s):  
Grazielle Oliveira ◽  
Marco Ceia ◽  
Roseane Missagia ◽  
Victor Santos ◽  
Irineu Lima Neto
Keyword(s):  
Wave Velocity ◽  
Carbonate Rocks ◽  
P Wave ◽  
P Wave Velocity

Empirical Equations of P-Wave Velocity in the Shallow and Semi-Deep Sea Sediments from the South China Sea

2021 ◽  
Vol 20 (3) ◽  
pp. 532-538
Author(s):  
Guanbao Li ◽  
Zhengyu Hou ◽  
Jingqiang Wang ◽  
Guangming Kan ◽  
Baohua Liu
Keyword(s):  
South China Sea ◽  
Wave Velocity ◽  
South China ◽  
Deep Sea ◽  
The South China Sea ◽  
P Wave ◽  
Empirical Equations ◽  
China Sea ◽  
P Wave Velocity ◽  
Deep Sea Sediments
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