Ali TALAEI - Petroleum engineering department, Petroleum University of technology, Ahwaz, Iran
Jamshid MOGHADASI

One of the most serious problems in the water injection process is scale formation occurrence when injection water is incompatible with formation brine.These two waters interact chemically and precipitate inorganic minerals. For example seawater with high concentration of sulfate ions as injection waterreaches to formation water with cationic ions. The purpose of this study is to predict the permeability reduction caused by deposition of scales in sandstonecores from mixing of injected sea water and highsalinity formation water at various temperatures (60- 100 °C) and differential pressures (50-150 psig).Several factors like particle movement, clay swelling and pore throat blocking by fines can disturb flooding test results and make doubt in prediction. Asa new method of electrical conductivity measurement the scale formation was predicted independent of non-related factors. The results showed that calcium, strontium, and barium sulfates are formed and cause permeability damage. CaSO4 and SrSO4 scales will deposit more in higher temperatures but BaSO4 scale deposit less. At higher pressures all of them precipitate more.

Formation damage, Incompatible waters, Inorganic scale formation, core flood,permeability decline, Electrical Conductivity