Authors: Research Council of Alberta
Water flooding operations in the Pembina Oil Field are partly carried out with oil field brines recovered elsewhere in the field; due to the highly corrosive nature of the brines and the absence of tubing in the injection wells it is highly probable that at some time the oil well casing will fail and the brine which is under a high injection pressure will be in direct contact with the shallow fresh water aquifers in the Paskapoo Formation. The following calculations are an attempt to give an estimate of the distance the brine will move outward from the well after a certain time in a hypothetical aquifer. The calculations are based on the formula given by Walton (1962), which gives the relation between the pressure head at the well, the time and the rate of discharge or recharge. It is further assumed that the brine completely displaces the fresh water and the radius of the resulting cylindrical body of brine can be calculated by equating the pore volume of this body to the volume of brine recharged. The hypothetical aquifer is assumed infinite in areal extent and non-leaky. The aquifer coefficients that were chosen are partly based on a report on the water resources of the Pembina area by Farvolden (1961) and partly on representative average values of fine to medium, partly cemented sandstone, the typical aquifer in the Paskapoo Formation. These coefficients are as follows:
Transmissibility (T): 500 U.S. gallons per foot per day;
Storage coefficient (S): 1.0 x 10-5
Porosity (f): 10%;
Thickness (m): 100 feet.