Rock Physics Modeling Research Papers (original) (raw)

In this study a tight carbonate gas reservoir of early Eocene (S1 formation) is studied for litho-facies estimation and probabilistic estimation of reservoir properties prediction using quantitative geophysical approach from a mature gas... more

In this study a tight carbonate gas reservoir of early Eocene (S1 formation) is studied for litho-facies estimation and probabilistic estimation of reservoir properties prediction using quantitative geophysical approach from a mature gas field in the Middle Indus Basin, onshore Pakistan. Quantitative seismic reservoir characterization approach relied on well based litho-facies re-classification, Amplitude Variation with Offset (AVO) attributes analysis and Pre-Stack simultaneous inversion attributes constrained with customized well-log and seismic data (gathers) conditioning. Three main litho-facies (hydrocarbon bearing limestone, tight limestone and shale) are classified estimated based on the precise analysis of well data using petrophysical properties. AVO attributes (intercept and gradient) conveniently inspection for amplitude behavior (reflection coefficients) of the possible AVO (class I), fluids and lithology characteristics. Probable litho-facies (tight limestone and shale)...

A probabilistic model of the expected behavior of the AVO attributes can provide the means for QC’ing the seismic data at the end of the processing sequence in view of the “amplitude resolution” compliance. The usage of such AVO based... more

A probabilistic model of the expected behavior of the AVO attributes can provide the means for QC’ing the seismic data at the end of the processing sequence in view of the “amplitude resolution” compliance. The usage of such AVO based pre-stack amplitude QC allows a first level standard evaluation of the suitability of the amplitude information of the partial stack volumes for any kind of quantitative analysis of seismic data. If a discrepancy is highlighted here, it might indicate that the applied processing sequence did not succeed in recovering and preserving original amplitudes, thus calling for a more detailed investigation of the causes and search for possible remedies.

The sandstone reservoir in the “OA” Field is situated in the Northern Bonaparte Basin, which is gas-saturated sandstone. Mineral diagenesis is also causing several reservoir zone areas to become tight sand. The inversion method using... more

The sandstone reservoir in the “OA” Field is situated in the Northern Bonaparte Basin, which is gas-saturated sandstone. Mineral diagenesis is also causing several reservoir zone areas to become tight sand. The inversion method using acoustic impedance (AI) is less sensitive in distinguishing sandstone and clay rock lithology since they have almost the same impedance. Simultaneous Inversion overcomes this problem by simultaneously inversing partial angle data (near, mid, far) to obtain physical parameters besides acoustic impedance which are expected to be more sensitive in distinguishing lithology and predicting the presence of gas fluids such as shear impedance (SI) and density. These three parameters can be derived as Lame (LMR) parameters. Cross plot analysis shows sensitive physical parameters to predict the distribution of lithology and the presence of gas fluid. Density sensitive in distinguishing lithology which is then inverted, obtaining sandstone cutoff values are 2.3-2.5...

Partially saturated reservoirs are one of the major sources of seismic wave attenuation, modulus defect and velocity dispersion in real seismic data. The main attenuation and dispersion phenomenon is wave induced fluid flow due to the... more

Partially saturated reservoirs are one of the major sources of seismic wave attenuation, modulus defect and velocity dispersion in real seismic data. The main attenuation and dispersion phenomenon is wave induced fluid flow due to the heterogeneity in pore fluids or porous rock. The identification of pore fluid type, saturation and distribution pattern within the pore space is of great significance as several seismic and petrophysical properties of porous rocks are largely affected by fluid type, saturation and fluid distribution pattern. Based on Gassmann-Wood and Gassmann- Hill rock physics models modulus defect, velocity dispersion and attenuation in Jurassic siliclastic partially-saturated rocks are studied. For this purpose two saturation patterns - uniform and patchy - are considered within the pore spaces in two frequency regimes i.e., lower frequency and higher frequency. The results reveal that at low enough frequency where saturation of liquid and gas is uniform, the seismic velocity and bulk modulus are lower than at higher frequency where saturation of fluid mixture is in the form of patches. The velocity dispersion and attenuation is also modeled at different levels of gas saturation. It is found that the maximum attenuation and velocity dispersion is at low gas saturation. Therefore, the dispersion and attenuation can provide a potential way to predict gas saturation and can be used as a property to differentiate low from high gas saturation.

Predictions of shear-wave logs in wells that do not have dipole Sonics are challenging, particularly in heavy oil reservoirs. In this study, we utilized linear-regression, robust locally weighted scattering and smoothing (LOWESS), and... more

Predictions of shear-wave logs in wells that do not have dipole Sonics are challenging, particularly in heavy oil reservoirs. In this study, we utilized linear-regression, robust locally weighted scattering and smoothing (LOWESS), and several other approaches of iteratively re-weighted linear least- squares inversion (IRLS) techniques to estimate shear-wave logs. The developed computer codes were implemented using well logs from three different types of reservoirs (conventional oil, heavy oil, and tight shale oil) in WCSB. The proposed methods guard against outliers, and have shown improvements in predicting shear-wave sonic logs compared to standard linear relationships (Castagna et. al., 1985).

In this study, we implemented three different time-lapse AVO inversion algorithms (total inversion of the differences, inversion of seismic difference only and sequential reflectivity-constrained inversion) using synthetic data that... more

In this study, we implemented three different time-lapse AVO inversion algorithms (total inversion of the differences, inversion of seismic difference only and sequential reflectivity-constrained inversion) using synthetic data that simulate a time-lapse model of a heavy oil reservoir. Elastic physical parameters of the time-lapse model were chosen to represent reservoir conditions at pre-production and post-production periods after reservoir depletion.

Bikaner–Nagaur basin is located in the northwestern part of India and lies on the rising flank of Punjab platform of Middle Indus basin in Pakistan. Existence of Neoproterozoic-Cambrian petroleum system was confirmed by the exploration... more

Bikaner–Nagaur basin is located in the northwestern part of India and lies on the rising flank of Punjab platform of Middle Indus basin in Pakistan. Existence of Neoproterozoic-Cambrian petroleum system was confirmed by the exploration activities in the western periphery of the basin, whereas vast areas of central and eastern parts remain unexplored. Knowledge of petroleum system in this unexplored part of the basin is limited due to non-availability of data. Recently, 2525 line km of regional 2D seismic data acquired for the first time by Government of India under National Seismic Program (NSP) unlocks the opportunity for comprehensive understanding of subsurface geology in unexplored part of the basin. Present work aims to interpret recently acquired 2D seismic data and integrate with available surface (outcrop) data, gravity and well data (drilled in western part of basin) for unfolding the petroleum system elements, structural configurations and stratigraphic features in the hit...

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... more

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 o...

Passive seismic low-frequency (from approximately [Formula: see text]) data have been acquired at several locations around the world. Spectra calculated from these data, acquired over fields with known hydrocarbon accumulations, show... more

Passive seismic low-frequency (from approximately [Formula: see text]) data have been acquired at several locations around the world. Spectra calculated from these data, acquired over fields with known hydrocarbon accumulations, show common spectral anomalies. Verification of whether these anomalies are common to only a few, many, or all hydrocarbon reservoirs can be provided only if more and detailed results are reported. An extensive survey was carried out above a tight gas reservoir and an adjacent exploration area in Mexico. Data from several hundred stations with three-component broadband seismometers distributed over approximately [Formula: see text] were used for the analysis. Severalhydrocarbon reservoir-related microtremor attributes were calculated, and mapped attributes were compared with known gas intervals, with good agreement. Wells drilled after the survey confirm a predicted high hydrocarbon potential in the exploration area. A preliminary model was developed to expl...

Bikaner–Nagaur basin is located in the northwestern part of India and lies on the rising flank of Punjab platform of Middle Indus basin in Pakistan. Existence of Neoproterozoic-Cambrian petroleum system was confirmed by the exploration... more

Bikaner–Nagaur basin is located in the northwestern part of India and lies on the rising flank of Punjab platform of Middle Indus basin in Pakistan. Existence of Neoproterozoic-Cambrian petroleum system was confirmed by the exploration activities in the western periphery of the basin, whereas vast areas of central and eastern parts remain unexplored. Knowledge of petroleum system in this unexplored part of the basin is limited due to non-availability of data. Recently, 2525 line km of regional 2D seismic data acquired for the first time by Government of India under National Seismic Program (NSP) unlocks the opportunity for comprehensive understanding of subsurface geology in unexplored part of the basin. Present work aims to interpret recently acquired 2D seismic data and integrate with available surface (outcrop) data, gravity and well data (drilled in western part of basin) for unfolding the petroleum system elements, structural configurations and stratigraphic features in the hit...

The amplitude variation with offset (AVO) or angle of incidence (AVA) is sensible to several factors that may affect the feasibility of doing this kind of analysis. This work evaluates how the available long offset, level of random noise... more

The amplitude variation with offset (AVO) or angle of incidence (AVA) is sensible to several factors that may affect the feasibility of doing this kind of analysis. This work evaluates how the available long offset, level of random noise and impedance contrast affect the estimation of the AVO parameters (intercept, gradient and curvature). An oil sand, with a class-III AVO anomaly, constitutes the geological framework. Fluid replacement modelling was used in order to extent the analysis to three different impedance contrast scenarios: gas, oil and water filling the pore space. Firstly, we analyzed the AVO response with no noise and offsets related to angle of incidence up to 45 degrees. This case was taken as reference to measure the error and standard deviation in the AVO-parameter estimation when decreasing the available offset and varying the level of noise. The results, for the gas case, show that the intercept is practically not impacted by the reduction of offset and is slight...

The effects of left ventricular hypertrophy (LVH) on systolic function were studied by echocardiography in 61 hypertensive patients. LV mass index (LVMI) and relative wall thickness (h/r ratio) were used together as LVH indices, and three... more

The effects of left ventricular hypertrophy (LVH) on systolic function were studied by echocardiography in 61 hypertensive patients. LV mass index (LVMI) and relative wall thickness (h/r ratio) were used together as LVH indices, and three patterns of LV adaptation to the pressure overload were observed: 13 patients had normal LVMI and h/r ratio (no LVH); 32 patients had increased h/r ratio, with normal or increased LVMI (concentric LVH); 16 patients had increased LVMI and normal h/r ratio (eccentric LVH). Cuff arterial pressure was lower in patients without LVH than in those with LVH, but both LVH indices correlated weakly with systolic, diastolic, and mean blood pressure (r = 0.22 to 0.33). Eccentric LVH showed peculiar hemodynamics, characterized by high cardiac output (CO) and normal total peripheral resistance (TPR), whereas CO was normal and TPR moderately and severely increased in patients without LVH and with concentric LVH, respectively. In the group without LVH, peak systol...

En el presente artículo se describe la construcción de dispositivos experimentales elaborados con materiales de fácil adquisición como apoyo para la enseñanza de algunos conceptos electromagnéticos en el Tecnológico Nacional de México.... more

En el presente artículo se describe la construcción de dispositivos experimentales elaborados con materiales de fácil adquisición como apoyo para la enseñanza de algunos conceptos electromagnéticos en el Tecnológico Nacional de México. Basados en un modelo de enseñanza constructivista, se propone que dichos experimentos sean utilizados como parte del proceso de enseñanza, ya que permiten apreciar en forma directa los conceptos que explican adecuadamente los fenómenos naturales, además de propiciar una mejor comprensión de los mismos. Asimismo, conduce al alumno al desarrollo de proyectos, a la búsqueda y adquisición de materiales, al diseño y elaboración del prototipo y por supuesto, a mostrar el concepto de manera plausible.

Digital Rock Physics (DRP), in combination with state of the art 3D imaging techniques, such as high resolution micro CT (µ-CT) or Synchrotron CT (Sr-CT), has progressed to a well established methodical instrument for petrophysical... more

Digital Rock Physics (DRP), in combination with state of the art 3D imaging techniques, such as high resolution micro CT (µ-CT) or Synchrotron CT (Sr-CT), has progressed to a well established methodical instrument for petrophysical process modeling and simulations at the pore scale, respectively. Besides hydraulic and acoustic (elastic) rock properties, which probably form the largest field of interest for DRP, electric conductivity / resistivity is also of great interest since it is essentially used to determine (e.g.) water saturation, formation producibility, and at least the volume of oil- and/or gas in place of the formation. For this, formation resistivity factor (F) is measured by default during classic core analysis in the laboratory, in order to evaluate the parameters as mentioned above and to characterize the pore system of the rock in more detail. Nevertheless, to provide reliable statistics, experimental time increases significantly, same as the amount of cores that nee...