Abstract: This research work examined the effects of formation water, Sea water and Injection water on the rheological properties of crude oil from an off- shore field in the Niger-Delta area of Nigeria. Flow properties analyses were determined at ambient temperature (770F) and reservoir fluid critical Temperature (1770F). Analysis of the mixture of the crude oil and water samples were carried out at various ratios of (80/20 and 50/50) % respectively. Test results indicated that the addition of water to crude oil sample increased the values of most of the flow properties at both ambient and critical temperatures. However some crude oil flow properties like (Viscosity, pH, Density, Specific gravity and Electrical conductivity) showed the highest incremental values with formation water sample than in Sea water and Injection water samples at both ambient and formation temperature. At 80/20 ratio the viscosity of crude oil increased from 3.8 cst to 4.2cst with the addition of formation water, 4.0 cst and 3.9 cst with sea water and injection water samples respectively, the values for 50/50 ratio gave 4.5 cst, 4.2 cst and 4.0 cst for formation, sea and injection water samples respectively at ambient temperature. At 80/20 ratio, the pH of the crude oil sample increased from 4.58 to 5.20 on addition of formation water, 4.90 and 4.60 with sea and injection water samples respectively, the values for 50/50 ratios were 7.9, 6.5 and 5.2 for formation water, seawater and injection water samples respectively at ambient temperature. The specific gravity at 80/20 ratio increased from 0.788 to 0.816, 0.806 and 0.797 on dilution with formation, sea and injection water samples respectively, the 50/50 ratio gave 0.993, 0.966 and 0.953 for formation water, sea water and injection water respectively at ambient temperature. The influx of water samples at 80/20 and 50/50 ratio also increased the density of crude oil at both temperatures. Therefore in other to minimize the variation in crude oil properties normally experienced during production, the analysis of the effect of different sources of water on crude oil properties should be employed.
Keywords: Flow properties, Formation water, Electrical conductivity, viscosity, Density