Non-Darcy Flow: Laboratory Measurements in Unconsolidated Porous Media

Abstract

In recent years, the petroleum industry has shown a renovated interest in Non-Darcy flow, in order to better understand reservoir performances. Non-Darcy flow is typically observed in gas wells when the fluids converging to the wellbore attains the velocity peculiar of turbulent flow. As a consequence, pressure drop around the wellbore cannot be estimated from the classic Darcy equation, where the pressure gradient is a linear function of the flow velocity. In that case, in fact, the use of Darcy equation would lead to inaccurate production performances evaluation.In order to describe correctly this phenomenon, the well-known Forchheimer equation is normally used, where the inertial coefficient β is defined. In gas wells this coefficient is usually determined by the analysis of multi-rate pressure tests performed on site. Unfortunately, such data are not easily available (or not economical) in many cases. So, it is a common practice to use particular theoretical and empirical correlations that can be derived by exploiting experimental values of the inertial coefficient.This paper reports a laboratory study in which the inertial coefficient β can be correlated to the structure of the porous media, and, in particular, of its grain size distribution. Gas flow laboratory experiments have been performed on laboratory models of glass beads and natural sands of different sizes. Moreover, porosity and permeability, together with the Klinkenberg constant, have been determined on natural sand cores with both flat and peaked grain size distribution, and a correlation with the Forchheimer equation has been checked. Forchheimer's number has been calculated and correlated to the superficial velocity as well. In the light of the above, specific laboratory equipment has been devised in order to rely on a wide range of flow rate under appropriate pressure gradients.

An Integration Approach for Evaluating Well Deliverability in Ultra Deep Sands

“…The flow characteristics and geological features of Low permeability reservoir is complex, the original formation pressure reservoir is low, the supplementary energy is not enough, the production and efficiency of single well is poor, and the non-Darcy flow characteristics, pressure gradient and stress sensitivity characteristics is existed, resulting in the recovery ratio of low permeability recovery is low, there are difficulties in production 13 .…”

Efectos de la microestructura en el comportamiento hidromecánico de suelos compactados

“…Para observar muestras húmedas o saturadas en el ESEM se requiere que la muestra esté cubierta por una membrana, lo que representa un obstáculo en la caracterización de la superficie de la muestra y dificulta el análisis de las imágenes que se obtienen. Por esta razón, diversos investigadores han preferido el uso de nuevas técnicas de observación como la microscopía electrónica de barrido de emisión de campo (FESEM) para analizar los cambios microestructurales sufridos por los suelos a lo largo de trayectorias hidromecánicas (Foster et al, 2004;Agus y Schanz 2005;Martínez et al, 2005;Viola et al, 2005;Macini et al, 2007;Kassim et al, 2010;Amaral 2012;Arenas-Lago et al, 2013;Arroyo et al, 2013;Díaz-Hernández et al, 2013;Mokni et al, 2014). Este nuevo tipo de microscopios SEM trabajan utilizando como fuente de electrones un cañón de emisión de campo (Field Emission Gun) que genera haces de electrones de alta y baja energía más focalizados, que permite mejorar la resolución y minimizar las cargas sobre el espécimen.…”

“…Todas estas características hacen del FESEM un método de ultraalta resolución para el análisis cualitativo de los arreglos de los agregados, de las partículas y de los poros en suelos no saturados. Diversos investigadores han empleado el FESEM con éxito en la caracterización microestructural de distintos tipos de suelos (Foster et al, 2004;Agus y Schanz, 2005;Martínez et al, 2005;Viola et al, 2005;Macini et al, 2007;Kassim et al, 2010;Amaral, 2012;Arenas-Lago et al, 2013;Arroyo et al, 2013;Díaz-Hernández et al, 2013;Mokni et al, 2014). El funcionamiento del FESEM es el mismo que el de un SEM convencional: un haz de electrones barre la superficie de la muestra mientras que la información que interesa, en función de los detectores disponibles, se visualiza en un monitor.…”