Effective porosity

About: Effective porosity is a research topic. Over the lifetime, 1199 publications have been published within this topic receiving 26511 citations.

Determination of oil and gas in place: conventional and unconventional reservoirs

Abstract: The simplest method to determine the quantity of original oil and gas in place in conventional reservoirs is volumetric analysis. First, the bulk volume of the reservoir is determined by knowing the reservoir boundaries and formation thickness. Next, the pore volume is determined based on rock porosity. Subsequently, the hydrocarbon pore volume (HCPV) is estimated when the saturation of fluids in the porous network is known. Finally, knowledge of formation volume factor of oil and gas is required to convert the volumes under reservoir conditions of pressure and temperature to standard surface conditions.

Experimental assessment of the infiltration properties of a coarse soil medium in a dielectric infiltration test.

Abstract: An accurate determination of the hydrological characteristics of porous media, such as the values of the porosity and effective porosity, are essential. This is important to understand the transport processes of infiltration and the movement of water and contaminants in the porous media. In this study, a laboratory soil column experiment to estimate the porosity and effective porosity of Toyoura standard sand samples, using a dielectric method termed the frequency domain reflectometry with vector network analyzer (FDR-V), was performed. The FDR-V device uses high-frequency microwaves, ranging from 0.1 to 3 GHz, to measure the complex dielectric constants of the sample. From the measured complex dielectric constant, the two parameters of the soil samples then were derived, using a proposed dielectric mixture model and tracer concentration model. The effective porosity of the soil sample is measured at 0.311 with the FDR-V dielectric method and 0.345 by the soil tracer column test. Comparing this with the calculated porosities of the soil sample, the ratio of effective porosity is approximately 78% for the dielectric method, and approximately 86% for the tracer concentration method. These different values can be explained to be within the measurement range with regard to the measurement volume for the soil column. These results indicate that measurement by the dielectric method using an FDR-V device is an efficient and useful tool for estimating the hydrological parameters of porous media because of the dielectric response of earth materials.

Conceptual definition of porosity function for coarse granular porous media with fixed texture

Abstract: Porous media’s porosity value is commonly taken as a constant for a given granular texture free from any type of imposed loads. Although such definition holds for those media at hydrostatic equilibrium, it might not be hydrodynamically true for media subjected to the flow of fluids. This article casts light on an alternative vision describing porosity as a function of fluid velocity, though the media’s solid skeleton does not undergo any changes and remain essentially intact. Carefully planned laboratory experiments support such as hypothesis and may help reducing reported disagreements between observed and actual behaviors of nonlinear flow regimes. Findings indicate that the so-called Stephenson relationship that enables estimating actual flow velocity is a case that holds true only for the Darcian conditions. In order to investigate the relationship, an accurate permeability should be measured. An alternative relationship, therefore, has been proposed to estimate actual pore flow velocity. On the other hand, with introducing the novel concept of effective porosity, that should be determined not only based on geotechnical parameters, but also it has to be regarded as a function of the flow regime. Such a porosity may be affected by the flow regime through variations in the effective pore volume and effective shape factor. In a numerical justification of findings, it is shown that unsatisfactory results, obtained from nonlinear mathematical models of unsteady flow, may be due to unreliable porosity estimates.

Extending DFA-based multiple linear regression inference: Application to acoustic impedance models

Abstract: In this paper we propose three distinct points for improving scale sensitive DFA based multiple linear regression inference: the scale dependent standardized Regression Coefficients β ˆ s t d D F A s as a measure of dependent variables relative importance, scale dependent effect size f 2 ( s ) , and Intersection-Union hypothesis test, which can handle the composite hypothesis of no cross-correlation, and of having no advantage over the standard OLS linear regression model. We applied this framework on a model for acoustic impedance of well log data, as a function of neutron effective porosity, shale volume, and resistivity. We find that the neutron effective porosity is more important for modeling acoustic impedance than resistivity and, that both are more important than the shale volume, for all scales. Results from Intersection-Union test suggest the rejection of compound null hypothesis for neutron effective porosity and resistivity for scales between 40 and 500 ft, suggesting a robust model for acoustic impedance based on neutron effective porosity and resistivity on these scales. This approach represents a novel framework for scale sensitive regression models, and we believe that it can be useful for time series studies in many diverse areas.

Fractal dimension measuring and calculating method for effective pores of hydrate-containing sediments

Abstract: The invention belongs to the field of basic physical property testing of unconventional oil and gas reservoir engineering and geotechnical engineering and particularly relates to a fractal dimension measuring and calculating method for effective pores of hydrate-containing sediments. Firstly, X-CT gray images of the hydrate-containing sediments are acquired and the porosity is measured; then, thegray images are colored again, X-CT colored images of the hydrate-containing sediments are acquired from two groups with gray values of soil particles, hydrate particles, gas and moisture in obvious comparison, then, X-CT colored images with set thresholds are subjected to binarization processing, black and white images are obtained, the effective porosity of the acquired black and white images isthe same as that of the X-CT gray images, and white and black represent a framework material and a pore fluid respectively. The fractal dimensions of black areas in the black and white images, namely, the fractal dimensions of effective porosity of the hydrate-containing sediments, are solved. The problems that solid framework space and pore fluid space cannot be segmented effectively with existing methods are solved, and the fractal dimensions of effective porosity of the hydrate-containing sediments can be measured and calculated accurately.