Effets de la texture petrographique sur les proprietes petrophysiques d'un calcaire en zone de diagenese meteorique (calcaire oligocene d'Aquitaine, France)

2000 ◽  
Vol 171 (4) ◽  
pp. 419-430 ◽  
Author(s):  
Adrian Cerepi ◽  
Louis Humbert ◽  
Rene Burlot
Keyword(s):  
Porous Medium ◽  
Specific Surface ◽  
Pore Space ◽  
Space Complexity ◽  
Petrophysical Properties ◽  
Chemical Analyses ◽  
Reservoir Properties

Abstract 120 samples of three quarries of the Oligocene Aquitaine limestone were subjected to petrographic, petrophysical and chemical analyses. Strong variations of depositional and diagenetic textures were observed. Four main depositional textures characterize this limestone: mudstone-wackestone, packstone, packstone-grainstone and grainstone. The diagenetic transformations recognized and specially meteoric leaching increases the heterogeneity of porous medium. The "Pierre de Bordeaux" shows a high variation of porosity (12,8 % to 42,51%), permeability (4,27 to 4755 mD), specific surface (0,78 to 3,73 m 2 /g) and distribution of pore throats (from monomodal to three modal distribution). Petrophysical properties depend strongly on depositional and diagenetic patterns. Textures with two and three modal distribution of porous medium, packstone-grainstone and grainstone have the best reservoir properties. The meteoric dissolution associated to microfracturing improves strongly both the macroporosity, permeability in mudstone-wackestone and packstone and increases the pore space complexity in all textures.

scholarly journals An Integrated Microfacies and Well Logs-Based Reservoir Characterization of Yamama Formation, Southern Iraq

2021 ◽  
pp. 3570-3586
Author(s):  
Mohanad M. Al-Ghuribawi ◽  
Rasha F. Faisal
Keyword(s):  
Reservoir Characterization ◽  
Water Saturation ◽  
Effective Porosity ◽  
Well Logs ◽  
Petrophysical Properties ◽  
Reservoir Properties ◽  
Thin Sections ◽  
Porosity And Permeability ◽  
South Of Iraq ◽  
Southern Iraq

     The Yamama Formation includes important carbonates reservoir that belongs to the Lower Cretaceous sequence in Southern Iraq. This study covers two oil fields (Sindbad and Siba) that are distributed Southeastern Basrah Governorate, South of Iraq. Yamama reservoir units were determined based on the study of cores, well logs, and petrographic examination of thin sections that required a detailed integration of geological data and petrophysical properties. These parameters were integrated in order to divide the Yamama Formation into six reservoir units (YA0, YA1, YA2, YB1, YB2 and YC), located between five cap rock units. The best facies association and petrophysical properties were found in the shoal environment, where the most common porosity types were the primary (interparticle) and secondary (moldic and vugs) . The main diagenetic process that occurred in YA0, YA2, and YB1 is cementation, which led to the filling of pore spaces by cement and subsequently decreased the reservoir quality (porosity and permeability). Based on the results of the final digital  computer interpretation and processing (CPI) performed by using the Techlog software, the units YA1 and YB2 have the best reservoir properties. The unit YB2 is characterized by a good effective porosity average, low water saturation, good permeability, and large thickness that distinguish it from other reservoir units.

scholarly journals A Possible Relation Between Grain Size, Density, and Light Attenuation in Natural Snow Cover

1970 ◽  
Vol 9 (55) ◽  
pp. 154-156
Author(s):  
James D. Bergen
Keyword(s):  
Grain Size ◽  
Porous Medium ◽  
Specific Surface ◽  
Snow Cover ◽  
Extinction Coefficient ◽  
Light Attenuation ◽  
Empirical Relation ◽  
Air Permeability ◽  
Fair Agreement ◽  
Natural Snow

AbstractThe extinction coefficient for the transmission of light through snow cover is related to the grain size and density of the snow cover. The connection is made by means of an empirical relation between the latter parameters and the air permeability and by the Carmen–Kozney relation between the air permeability and specific surface of a porous medium. The results are compared with a set of measurements found in the literature with fair agreement between the predicted and measured values of the extinction coefficient.

scholarly journals The transport of liquids in softwood: timber as a model porous medium

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
H. C. Burridge ◽  
G. Wu ◽  
T. Reynolds ◽  
D. U. Shah ◽  
R. Johnston ◽  
...  
Keyword(s):  
Experimental Data ◽  
Porous Medium ◽  
Fluid Flow ◽  
Transport Properties ◽  
Pore Space ◽  
Construction Material ◽  
Sustainable Construction ◽  
Natural Material ◽  
Full Potential ◽  
Treatment Processes

AbstractTimber is the only widely used construction material we can grow. The wood from which it comes has evolved to provide structural support for the tree and to act as a conduit for fluid flow. These flow paths are crucial for engineers to exploit the full potential of timber, by allowing impregnation with liquids that modify the properties or resilience of this natural material. Accurately predicting the transport of these liquids enables more efficient industrial timber treatment processes to be developed, thereby extending the scope to use this sustainable construction material; moreover, it is of fundamental scientific value — as a fluid flow within a natural porous medium. Both structural and transport properties of wood depend on its micro-structure but, while a substantial body of research relates the structural performance of wood to its detailed architecture, no such knowledge exists for the transport properties. We present a model, based on increasingly refined geometric parameters, that accurately predicts the time-dependent ingress of liquids within softwood timber, thereby addressing this long-standing scientific challenge. Moreover, we show that for the minimalistic parameterisation the model predicts ingress with a square-root-of-time behaviour. However, experimental data show a potentially significant departure from this $$\sqrt{{\boldsymbol{t}}}$$t behaviour — a departure which is successfully predicted by our more advanced parametrisation. Our parameterisation of the timber microstructure was informed by computed tomographic measurements; model predictions were validated by comparison with experimental data. We show that accurate predictions require statistical representation of the variability in the timber pore space. The collapse of our dimensionless experimental data demonstrates clear potential for our results to be up-scaled to industrial treatment processes.

Petrophysical properties variation of bitumen-bearing carbonates at increasing temperatures from laboratory to model

Geophysics ◽  
2020 ◽  
Vol 85 (5) ◽  
pp. MR297-MR308
Author(s):  
Roberta Ruggieri ◽  
Fabio Trippetta
Keyword(s):  
Central Italy ◽  
Carbonate Reservoir ◽  
P Wave ◽  
Petrophysical Properties ◽  
S Wave ◽  
Reservoir Properties ◽  
Velocity Change ◽  
Seismic Properties ◽  
Wave Velocities ◽  
Velocity Changes

Variations in reservoir seismic properties can be correlated to changes in saturated-fluid properties. Thus, the determination of variation in petrophysical properties of carbonate-bearing rocks is of interest to the oil exploration industry because unconventional oils, such as bitumen (HHC), are emerging as an alternative hydrocarbon reserve. We have investigated the temperature effects on laboratory seismic wave velocities of HHC-bearing carbonate rocks belonging to the Bolognano Formation (Majella Mountain, central Italy), which can be defined as a natural laboratory to study carbonate reservoir properties. We conduct an initial characterization in terms of porosity and density for the carbonate-bearing samples and then density and viscosity measurements for the residual HHC, extracted by HCl dissolution of the hosting rock. Acoustic wave velocities are recorded from ambient temperature to 90°C. Our acoustic velocity data point out an inverse relationship with temperature, and compressional (P) and shear (S) wave velocities show a distinct trend with increasing temperature depending on the amount of HHC content. Indeed, samples with the highest HHC content show a larger gradient of velocity changes in the temperature range of approximately 50°C–60°C, suggesting that the bitumen can be in a fluid state. Conversely, below approximately 50°C, the velocity gradient is lower because, at this temperature, bitumen can change its phase in a solid state. We also propose a theoretical model to predict the P-wave velocity change at different initial porosities for HHC-saturated samples suggesting that the velocity change mainly is related to the absolute volume of HHC.

scholarly journals Multifractal Analysis of Pore Structure and Evaluation of Deep-Buried Cambrian Dolomite Reservoir with Image Processing: A Case from Tarim Basin, NW China

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Xiaojun Zhang ◽  
Haodong Han ◽  
Jun Peng ◽  
Yingchun Gou
Keyword(s):  
Pore Structure ◽  
Thin Section ◽  
Tarim Basin ◽  
Clustering Analysis ◽  
Multifractal Analysis ◽  
Pore Space ◽  
Tectonic Activity ◽  
Petrophysical Properties ◽  
Nw China ◽  
Crystalline Dolomite

Reservoir pore space assessment is of great significance for petroleum exploration and production. However, it is difficult to describe the pore characteristics of deep-buried dolomite reservoirs with the traditional linear method because these rocks have undergone strong modification by tectonic activity and diagenesis and show significant pore space heterogeneity. In this study, 38 dolostone samples from 4 Cambrian formations of Tarim Basin in NW China were collected and 135 thin section images were analyzed. Multifractal theory was used for evaluation of pore space heterogeneity in deep-buried dolostone based on thin section image analysis. The physical parameters, pore structure parameters, and multifractal characteristic parameters were obtained from the digital images. Then, the relationships between lithology and these parameters were discussed. In addition, the pore structure was classified into four categories using K-means clustering analysis based on multifractal parameters. The results show that the multifractal phenomenon generally exists in the pore space of deep-buried dolomite and that multifractal analysis can be used to characterize the heterogeneity of pore space in deep-buried dolomite. For these samples, multifractal parameters, such as αmin, αmax, ΔαL, ΔαR, Δf, and AI, correlate strongly with porosity but only slightly with permeability. However, the parameter Δα, which is usually used to reveal heterogeneity, does not show an obvious link with petrophysical properties. Of dolomites with different fabrics, fine crystalline dolomite and medium crystalline dolomite show the best petrophysical properties and show significant differences in multifractal parameters compared to other dolomites. More accurate porosity estimations were obtained with the multifractal generalized fractal dimension, which provides a new method for porosity prediction. The various categories derived from the K-means clustering analysis of multifractal parameters show distinct differences in petrophysical properties. This proves that reservoir evaluation and pore structure classification can be accurately performed with the K-means clustering analysis method based on multifractal parameters of pore space in deep-buried dolomite reservoirs.

scholarly journals A Possible Relation Between Grain Size, Density, and Light Attenuation in Natural Snow Cover

1970 ◽  
Vol 9 (55) ◽  
pp. 154-156 ◽  
Author(s):  
James D. Bergen
Keyword(s):  
Grain Size ◽  
Porous Medium ◽  
Specific Surface ◽  
Snow Cover ◽  
Extinction Coefficient ◽  
Light Attenuation ◽  
Empirical Relation ◽  
Air Permeability ◽  
Fair Agreement ◽  
Natural Snow

Abstract The extinction coefficient for the transmission of light through snow cover is related to the grain size and density of the snow cover. The connection is made by means of an empirical relation between the latter parameters and the air permeability and by the Carmen–Kozney relation between the air permeability and specific surface of a porous medium. The results are compared with a set of measurements found in the literature with fair agreement between the predicted and measured values of the extinction coefficient.

Textural control on the quadrature conductivity of porous media

Geophysics ◽  
2016 ◽  
Vol 81 (5) ◽  
pp. E297-E309 ◽  
Author(s):  
Qifei Niu ◽  
Manika Prasad ◽  
André Revil ◽  
Milad Saidian
Keyword(s):  
Experimental Data ◽  
Porous Media ◽  
Specific Surface ◽  
Pore Volume ◽  
Pore Space ◽  
Surface Conductance ◽  
High Porosity ◽  
Textural Parameter ◽  
Clayey Materials ◽  
Low Porosity

Induced polarization (IP) has been broadly used for environmental and hydrogeological applications and in civil engineering. The IP response of a porous medium without metallic particles (described by its quadrature conductivity or its normalized chargeability) is controlled by the interfacial electrochemistry of the electrical double layer and the pore-space geometry. We use the specific surface per unit pore volume normalized by the formation factor (i.e., [Formula: see text]) as the controlling textural parameter for the quadrature conductivity. This relationship is obtained by averaging the surface conductance over the pore volume. A database that contains 76 samples (including porous borosilicate glass, sandstones, and clayey sediments) is used to check the new scaling. In addition to these data, we have conducted new IP measurements on 13 samples from the Middle Bakken Formation corresponding to low-porosity clayey materials. Comparison between the experimental data and our model confirms that the ratio [Formula: see text] is the dominant textural parameter describing the quadrature conductivity [Formula: see text] of a broad range of porous media. The database was also used to test whether the quadrature conductivity depended either on [Formula: see text], or the specific surface area [Formula: see text], or the ratio [Formula: see text] ([Formula: see text] being the connected porosity). Although the quadrature conductivity scales with [Formula: see text] and [Formula: see text] for high-porosity sandstones, these relationships are not appropriate for the low-porosity clayey materials presented in this study. However, experimental data support the dependence of the quadrature conductivity on [Formula: see text], a published relationship obtained through the volume averaging approach.

scholarly journals Pore-Scale Imaging of the Oil Cluster Dynamic during Drainage and Imbibition Using In Situ X-Ray Microtomography

Geofluids ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Junjian Li ◽  
Yajun Gao ◽  
Hanqiao Jiang ◽  
Yang Liu ◽  
Hu Dong
Keyword(s):  
Specific Surface ◽  
Capillary Pressure ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Space ◽  
Relative Volume ◽  
Pore Scale ◽  
X Ray ◽  
Cluster Dynamic ◽  
Remaining Oil

We imaged water-wet and oil-wet sandstones under two-phase flow conditions for different flooding states by means of X-ray computed microtomography (μCT) with a spatial resolution of 2.1 μm/pixel. We systematically study pore-scale trapping of the nonwetting phase as well as size and distribution of its connected clusters and disconnected globules. We found a lower Sor, 19.8%, for the oil-wet plug than for water-wet plug (25.2%). Approximate power-law distributions of the water and oil cluster sizes were observed in the pore space. Besides, the τ value of the wetting phase gradually decreased and the nonwetting phase gradually increased during the core-flood experiment. The remaining oil has been divided into five categories; we explored the pore fluid occupancies and studied size and distribution of the five types of trapped oil clusters during different drainage stage. The result shows that only the relative volume of the clustered oil is reduced, and the other four types of remaining oil all increased. Pore structure, wettability, and its connectivity have a significant effect on the trapped oil distribution. In the water sandstone, the trapped oil tends to occupy the center of the larger pores during the water imbibition process, leading to a stable specific surface area and a gradually decreasing oil capillary pressure. Meanwhile, in oil-wet sandstone, the trapped oil blobs that tend to occupy the pores corner and attach to the walls of the pores have a large specific surface area, and the change of the oil capillary pressure was not obvious. These results have revealed the well-known complexity of multiphase flow in rocks and preliminarily show the pore-level displacement physics of the process.

Probabilistic petrophysical-properties estimation integrating statistical rock physics with seismic inversion

Geophysics ◽  
2010 ◽  
Vol 75 (3) ◽  
pp. O21-O37 ◽  
Author(s):  
Dario Grana ◽  
Ernesto Della Rossa
Keyword(s):  
Seismic Data ◽  
Measurement Errors ◽  
Rock Physics ◽  
Seismic Inversion ◽  
Joint Estimation ◽  
Physical Models ◽  
Inversion Method ◽  
Petrophysical Properties ◽  
Reservoir Properties ◽  
Statistical Rock Physics

A joint estimation of petrophysical properties is proposed that combines statistical rock physics and Bayesian seismic inversion. Because elastic attributes are correlated with petrophysical variables (effective porosity, clay content, and water saturation) and this physical link is associated with uncertainties, the petrophysical-properties estimation from seismic data can be seen as a Bayesian inversion problem. The purpose of this work was to develop a strategy for estimating the probability distributions of petrophysical parameters and litho-fluid classes from seismics. Estimation of reservoir properties and the associated uncertainty was performed in three steps: linearized seismic inversion to estimate the probabilities of elastic parameters, probabilistic upscaling to include the scale-changes effect, and petrophysical inversion to estimate the probabilities of petrophysical variables andlitho-fluid classes. Rock-physics equations provide the linkbetween reservoir properties and velocities, and linearized seismic modeling connects velocities and density to seismic amplitude. A full Bayesian approach was adopted to propagate uncertainty from seismics to petrophysics in an integrated framework that takes into account different sources of uncertainty: heterogeneity of the real data, approximation of physical models, measurement errors, and scale changes. The method has been tested, as a feasibility step, on real well data and synthetic seismic data to show reliable propagation of the uncertainty through the three different steps and to compare two statistical approaches: parametric and nonparametric. Application to a real reservoir study (including data from two wells and partially stacked seismic volumes) has provided as a main result the probability densities of petrophysical properties and litho-fluid classes. It demonstrated the applicability of the proposed inversion method.

Sign in / Sign up

Export Citation Format

Share Document