Modeling and CT-Scan Study of the Effect of Core Heterogeneity on Foam Flow for Acid Diversion

Abstract

fax 01-972-952-9435. AbstractWe present a new 2D analysis based on the recently developed stochastic bubble population foam model, focusing on the effect of the core heterogeneity. In the frame of the model presented in a parent paper in the conference, we assume that the bubble generation kinetics is dependent on layer permeability. We present experiments consisting of coinjection of N 2 gas and surfactant solution in layered cores, with layering parallel and to the flow directions. The cores are obtained by combining two porous media chosen from Benteimer and Berea sandstone and sintered glass, with large permeability contrast. X-ray computed tomography (CT) scans are used to visualize and quantify local fluid distributions and differentiate foam propagation in the different layers. From both the model and the experiments we conclude that foam is primarily generated in the high-permeability layers, where it propagates at a much higher speed than in the low permeability layer. The propagation of foam in the low permeability layer requires that the pressure gradient is higher than the capillary entry pressure for the layer. The new stochastic population balance foam model reproduces rather well the main features of foam motion in heterogeneous cores containing a surfactant. Core floods combined with CT scan imaging provide valuable specific information about the effect of heterogeneity for better design of acid diversion operations.

Static and Dynamic Performance of Wet Foam and Polymer-Enhanced Foam in the Presence of Heavy Oil

“…At the initial stage of foam injection, bubbles first entered larger pore channels with lower entrance capillary pressure and the foam texture was coarse. Then, the local pressure gradient increased because of the increased foam flow resistance, and therefore foam bubbles entered relatively small pore channels [39]. The foam flow repeated this process until the steady state was reached.…”

Experimental Study on the Effect of Microheterogeneity on Multiphase Flow in a Microscopic Visualization Model

“…8 Through simulation, Farshbaf Zinati found that foam was mainly generated in high-permeability areas, and when the pressure gradient was large, the foam entered the low-permeability areas and expanded the swept volume. 9 Zhang et al found that foam flooding could block fractures and effectively displace residual oil in the matrix. 10 Bertin experimentally studied the formation and migration of foam in heterogeneous reservoirs and found that even with a permeability contrast of 67 between the highand low-permeability zones, the foam could still be transferred to the low-permeability zone.…”

“…For example, Yaghoobi studied the effect of foam flooding in heterogeneous cores and found that foam controlled the gas mobility well . Through simulation, Farshbaf Zinati found that foam was mainly generated in high-permeability areas, and when the pressure gradient was large, the foam entered the low-permeability areas and expanded the swept volume . Zhang et al found that foam flooding could block fractures and effectively displace residual oil in the matrix .…”

Experimental Research of Applicability Condition for Foam Flooding

“…Diversion means blocking high-permeability layer, and diverting subsequent fluid into low-permeability layer. Many researchers [2][3][4][5][6][7][8][9][10] agreed that foam does not increase water or acid viscosity, or alter the relationship between water relative permeability and water saturation in steady foam flow. Foam directly reduces gas mobility in rock, the low-mobility gas in turn drives down water saturation and thereby reduces water relative permeability and mobility.…”