scholarly journals Coupling Relationship between Multistage Fluid Activity and Reservoir Abnormally High-Porosity Zones in the Songtao–Baodao Region, Qiongdongnan Basin

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Xu Chen ◽  
Yao Wang ◽  
Ao Su
Keyword(s):  
Pore Space ◽  
Qiongdongnan Basin ◽  
Petroleum Exploration ◽  
High Porosity ◽  
Fluid Type ◽  
Positive Effects ◽  
Thermal Fluids ◽  
Diagenetic Minerals ◽  
Diagenetic Fluids ◽  
Diagenetic Fluid

An abnormally high-porosity zone (AHPZ) is beneficial for petroleum exploration, especially for the deep tight reservoirs in a petroliferous basin. Because of lacking effective research methods, it is hard to analyze the formation process of AHPZs in different geological periods. From the perspective of the diagenetic fluid type and activity history, geochemical characteristics and fluid inclusions of diagenetic minerals were utilized to reconstruct the diagenetic fluid type and dynamic evolution. The ultimate goal is to study the genetic process of AHPZs in the Songtao–Baodao region of the Qiongdongnan basin, South China Sea. It was found that there are three sections of AHPZs at different burial depths, which are generally favorable for high-quality reservoirs. Moreover, it can be concluded that the AHPZs are closely related to multiple actions of various diagenetic fluids. The meteoric waters, organic acid, and thermal fluids facilitated the enlargement of porosity by dissolving minerals to form secondary pore spaces. The hydrocarbon fluids have positive effects on the preservation of pores by preventing cement from filling the pore space.

scholarly journals Estimation of permeability and saturation based on imaginary component of complex resistivity spectra: A laboratory study

2020 ◽  
Vol 12 (1) ◽  
pp. 299-306
Author(s):  
Jiang Jia ◽  
Shizhen Ke ◽  
Junjian Li ◽  
Zhengming Kang ◽  
Xuerui Ma ◽  
...  
Keyword(s):  
Water Saturation ◽  
Pore Space ◽  
Evaluation Model ◽  
Low Frequency ◽  
Petroleum Exploration ◽  
Western China ◽  
Imaginary Component ◽  
Estimation Model ◽  
Complex Resistivity ◽  
Linear Relationships

AbstractLow-frequency resistivity logging plays an important role in the field of petroleum exploration, but the complex resistivity spectrum of rock also contains a large amount of information about reservoir parameters. The complex resistivity spectra of 15 natural sandstone cores from western China, with different water saturations, were measured with an impedance analyzer. The pore space of each core was saturated with NaCl solution, and measurements were collected at a frequency range of 40–15 MHz. The results showed a linear relationship between the real resistivity at 1 kHz and the maximum values of imaginary resistivity for each core with different water saturations. The slopes of the linear best-fit lines had good linear relationships with the porosity and the permeability of cores. Based on this, a permeability estimation model was proposed and tested. In addition, the maxima of imaginary resistivity had power exponential relationships with the porosity and the water saturation of the cores. A saturation evaluation model based on the maxima of imaginary resistivity was established by imitating Archie’s formula. The new models were found to be feasible for determining the permeability and saturation of sandstone based on complex resistivity spectrum measurements. These models advance the application of complex resistivity spectrum in petrophysics.

Permeability-porosity transforms from small sandstone fragments

Geophysics ◽  
2006 ◽  
Vol 71 (1) ◽  
pp. N11-N19 ◽  
Author(s):  
Ayako Kameda ◽  
Jack Dvorkin ◽  
Youngseuk Keehm ◽  
Amos Nur ◽  
William Bosl
Keyword(s):  
Pore Space ◽  
Petroleum Industry ◽  
Rock Physics ◽  
Three Dimensions ◽  
Absolute Permeability ◽  
High Porosity ◽  
Drill Cuttings ◽  
Thin Sections ◽  
Numerical Experimentation ◽  
The Absolute

Numerical simulation of laboratory experiments on rocks, or digital rock physics, is an emerging field that may eventually benefit the petroleum industry. For numerical experimentation to find its way into the mainstream, it must be practical and easily repeatable — i.e., implemented on standard hardware and in real time. This condition reduces the size of a digital sample to just a few grains across. Also, small physical fragments of rock, such as cuttings, may be the only material available to produce digital images. Will the results be meaningful for a larger rock volume? To address this question, we use a number of natural and artificial medium- to high-porosity, well-sorted sandstones. The 3D microtomography volumes are obtained from each physical sample. Then, analogous to making thin sections of drill cuttings, we select a large number of small 2D slices from a 3D scan. As a result, a single physical sample produces hundreds of 2D virtual-drill-cuttings images. Corresponding 3D pore-space realizations are generated statistically from these 2D images; fluid flow is simulated in three dimensions, and the absolute permeability is computed. The results show that small fragments of medium– to high-porosity sandstones that are statistically subrepresentative of a larger sample will not yield the exact porosity and permeability of the sample. However, a significant number of small fragments will yield a site-specific permeability-porosity trend that can then be used to estimate the absolute permeability from independent porosity data obtained in the well or inferred from seismic techniques.

Predicted Liquid Water Saturation in Unstructured Pore Networks Based on PEMFC GDL Porosity Profiles

2010 ◽  
Author(s):  
J. Hinebaugh ◽  
Z. Fishman ◽  
A. Bazylak
Keyword(s):  
Liquid Water ◽  
Water Saturation ◽  
Pore Space ◽  
Polymer Electrolyte Membrane ◽  
Gas Diffusion ◽  
Pore Network Model ◽  
High Porosity ◽  
Pore Networks ◽  
Electrolyte Membrane ◽  
Capillary Pressures

An unstructured, two-dimensional pore network model is employed to describe the effect of through-plane porosity profiles on liquid water saturation within the gas diffusion layer (GDL) of the polymer electrolyte membrane fuel cell. Random fibre placements are based on the porosity profiles of six commercially available GDL materials recently obtained through x-ray computed tomography experiments. The pore space is characterized with a Voronoi diagram, and invasion percolation-based simulations are performed. It is shown that water tends to accumulate in regions of relatively high porosity due to the lower associated capillary pressures. It is predicted that GDLs tailored to have smooth porosity profiles will have fewer pockets of high saturation levels within the bulk of the material.

scholarly journals The surface CO2 gradient and pore-space storage flux in a high-porosity litter layer

Tellus B ◽  
2004 ◽  
Vol 56 (4) ◽  
pp. 312-321 ◽  
Author(s):  
Adam I. Hirsch ◽  
Susan E.: Trumbore ◽  
Michael L. Goulden
Keyword(s):  
Pore Space ◽  
High Porosity ◽  
Litter Layer ◽  
Storage Flux

Chlorite interstratified with a 7 Å mineral: an example from offshore Norway and possible implications for the interpretation of the composition of diagenetic chlorites

Clay Minerals ◽  
1992 ◽  
Vol 27 (4) ◽  
pp. 475-486 ◽  
Author(s):  
S. Hillier ◽  
B. Velde
Keyword(s):  
Alternative Interpretation ◽  
High Porosity ◽  
X Ray Diffraction ◽  
Odd Order ◽  
Even Order ◽  
Diagenetic Minerals ◽  
Structural Formulae ◽  
Xrd Patterns ◽  
Diagenetic History ◽  
Pore Lining

AbstractX-ray diffraction (XRD) patterns of a pore-lining diagenetic chlorite (14 Å) from a reservoir sandstone, offshore Norway, show broad odd-order and sharp even-order basal reflections indicating that it contains 7 Å layers. Using NEWMOD, simulated XRD patterns with 15% 7 Å serpentine layers and a maximum crystallite thickness of 30 layers match the natural mineral well. Microprobe analyses of the 7 Å-14 Å mineral indicate that it is Fe-rich and aluminous suggesting that it is interstratified berthierine-chamosite. Apparent octahedral vacancies, however, suggest a significant dioctahedral component, and an alternative interpretation is interstratified kaolinite-chlorite. Indeed, chemical analyses of the mineral suggest a mixture of chlorite with 15% kaolinite, precisely the proportion of 7 Å layers indicated by XRD. Two other examples from the literature, previously identified as diagenetic chlorite, are probably also 7 Å-14 Å interstratified minerals, and the proportion of 7 Å layers indicated by XRD is also correlated with their structural formulae, if the 7 Å layers are, in fact, kaolinitic. This type of interstratification could explain why Fe-rich diagenetic chlorites appear to be compositionally distinct from metamorphic chlorites. The structure and chemistry of the Norwegian chlorite tend to support the idea that pore-lining chlorites form early in the diagenetic history, inhibiting the precipitation of later diagenetic minerals, and hence preserving abnormally high porosity at greater depths.

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.

Factors That Affect Gas-Condensate Relative Permeability

2014 ◽  
Vol 18 (01) ◽  
pp. 5-10 ◽  
Author(s):  
Subhash Kalla ◽  
Sergio A. Leonardi ◽  
Daniel W. Berry ◽  
Larry D. Poore ◽  
Hemant Sahoo ◽  
...  
Keyword(s):  
Relative Permeability ◽  
Water Saturation ◽  
Pore Space ◽  
Gas Condensate ◽  
Reservoir Rock ◽  
Fluid Type ◽  
Reservoir Conditions ◽  
Condensate Reservoir ◽  
House Design ◽  
Permeability Data

Summary When the pressure in a gas-condensate reservoir falls below the dewpoint, liquid condensate can accumulate in the pore space of the rock. This can reduce well deliverability and potentially affect the compositions of the produced fluids. Forecasting these effects requires relative permeability data for gas-condensate flow in the rock in the presence of immobile water saturation. In this study, relative permeability measurements were conducted on reservoir rock at a variety of conditions. The goal was to determine the sensitivity to interfacial tension (IFT) (which varies with pressure) and fluid type (reservoir fluids, pure hydrocarbons, and water). The results show a significant sensitivity to fluid type, as well as an IFT sensitivity that is similar to that reported by other researchers. For obtaining relative permeability data that are applicable to a specific reservoir, we conclude that laboratory measurements must be conducted at reservoir conditions with actual reservoir fluids. The measurements reported here used a state-of-the-art relative permeability apparatus of in-house design. The apparatus uses elevated temperature and pressure, precision pumps, and a sight glass with automated interface tracking. Closed-loop recirculation avoids the need for large quantities of reservoir fluids and ensures that the gas and liquid are in compositional equilibrium.

Influencing factor analysis of the elastic properties of shale with rock-physical model including pressure effects

2020 ◽  
Vol 8 (3) ◽  
pp. T515-T524
Author(s):  
Zhaoyun Zong ◽  
Man Jiang ◽  
Miaomiao Xu
Keyword(s):  
Elastic Moduli ◽  
Pore Space ◽  
Influencing Factor ◽  
Rock Physics ◽  
Critical Value ◽  
Pressure Effects ◽  
Petroleum Exploration ◽  
Solid Matrix ◽  
Effective Pressure ◽  
Shale Reservoirs

With the continuous petroleum exploration around the world, the target of exploration is converting from conventional to deep, unconventional reservoirs. The pressure condition on those new target layers is different from the conventional reservoir, and pressure is one of the important factors affecting the elastic moduli and velocities of shale reservoirs. Therefore, it is necessary to take pressure effects into consideration in rock-physics modeling. We initially adopted a novel iterative rock-physical modeling approach on the basis of pore space stiffness theory to analyze pressure’s influence on shale. Pore space stiffness theory assumes that pores own their own stiffness like the solid matrix of rocks, which is related to the effective pressure. We have implemented plenty of numerical analysis on the effect of pressure on shale and found out the most contributive factor to the moduli and velocities of shale. Our result indicates that when the effective pressure is smaller than the critical value, the elastic moduli and elastic wave velocities of shale increase significantly with the increase of effective pressure. The elastic moduli and velocities tend to be constant when the effective pressure goes beyond that critical value. By comparison, we found that the most contributive mineral in shale is clay, and the porosity has the greatest effect on elastic moduli and velocities when the mineral composition of shale stays unchanged. The influence of pressure is not as obvious as other factors in shale reservoirs with low porosity (lower than 10%) because pores occupy a relatively small percentage of the total volume.

PEM Fuel Cell Gas Diffusion Layer Modelling of Pore Structure and Predicted Liquid Water Saturation

2011 ◽  
Author(s):  
J. Hinebaugh ◽  
A. Bazylak
Keyword(s):  
Fuel Cell ◽  
Diffusion Layer ◽  
Liquid Water ◽  
Water Saturation ◽  
Pore Space ◽  
Three Dimensional ◽  
Gas Diffusion Layer ◽  
Gas Diffusion ◽  
Pore Network Model ◽  
High Porosity

An unstructured, three-dimensional pore network model is employed to describe the effect of through-plane porosity profiles on liquid water saturation within the gas diffusion layer (GDL) of the polymer electrolyte membrane fuel cell. Random fibre placements are based on the porosity profiles of six commercially available GDL materials recently obtained through x-ray computed tomography experiments. The pore space is characterized with a maximal ball algorithm, and invasion percolation-based simulations are performed. It is shown that water tends to accumulate in regions of relatively high porosity due to the lower associated capillary pressures. It is predicted that GDLs tailored to have smooth porosity profiles will have fewer pockets of high saturation levels within the bulk of the material. The results provide a more detailed picture of the possible water distributions in GDLs during operation.

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