The Use of Cement for Excluding Water from Oil-Sands in Drilling Wells

In connection with the drilling of oil wells, cement is being used in increasing quantities for excluding from the oil sand the water in strata nearer the surface. This water, if not prevented from going down into the oil sand, will displace the oil, because of its greater specific gravity, and eventually ruin the well. Unfortunately, the damage does not end here, for experiences in the older fields have shown that this flooding of the oil sand spreads gradually over wide areas, depending mainly on the porosity of the sand and the gravity of the oil, and, unless checked in some manner, will ruin neighboring wells. For this reason the encroachment of water into the oil-bearing strata is a serious problem in any oil-field, and is particularly difficult to overcome where the water strata are directly above or below the oil-bearing sand.