Page 271 - Reservoir Formation Damage

Two-Phase Formation Damage by Fines Migration 251

Porosity and Permeability Variation

The porosity is expressed by (Liu and Civan, 1996):

(11-51)
*JSj
J S j
and the permeability is estimated by (Liu and Civan, 1996)

(11-52)

Filter Cake Formation on the Injection Face

When the suspended particles existing in the injected fluid are large
enough they cannot invade the formation or when a sufficient amount of
fine particles are deposited in the porous formation to prevent particle
invasion, a filter cake formation begins over the injection face. Liu and
Civan (1995, 1996) applied a rate equation for the filter cake buildup
similar to (Peng and Peden, 1992):

d±
(11-53)
dt

Model Assisted Analysis of Experimental Data*
In this section, the application of the model to the analysis of formation
damage in a variety of core tests is demonstrated. The model was vali-
dated and model parameters were determined using the data of core tests.

Damage by Formation Fines Migration
Sarkar and Sharma (1990) examined fines migration in two Berea core
samples, one of them containing residual oil (ROS). Data for the two core
tests are given in Table 11-1. The core samples were first saturated with
3% NaCl brine. Formation damage due to fines migration took place upon
fresh water injection. Values of some model parameters were gathered
from Khilar and Fogler (1983) while the others were obtained by matching
the model responses to the measured data, as summarized in Table 11-2.

Reproduced by permission from Liu and Civan, ©1996 SPE; reprinted by permission
of the Society of Petroleum Engineers.