AN APPRAISAL ON WATER INJECTION PROPERTIES FROM WATER WELLS IN THE NIGER DELTA AREA OF NIGERIA.

Abstract

Physicochemical properties of injection water from five water wells in an offshore location at the Niger Delta area of Nigeria were analyzed with Silt density index assembly, HACH turbidimeter, pH meter, dissolved oxygen chemet kit, Innolab conductivity meter, metrohm titrator, pressure millipore vacuum pump assembly and labege kits using standard methods (American standard for testing and materials). Samples were obtained after filtration and chemical treatment at different periods within two months. Results obtained; silt density Index (0.830-1.480), plugging index (0.067-0.130), turbidity (0.310-0.650 NTU), pH (7.900-8.280), dissolved oxygen (10.000 – 15.000 ppb),  electrical conductivity (5.490-6.810 ms/cm), salinity (1000.000-4000.00 mg/l), total suspended solids (0.800 – 1.700 mg/l) show that all the measured parameters were within specification as recommended by American  Petroleum Institute (API). Bacterial inoculation was carried out on the sample before and after biocide batch treatment and observed within twenty eight days to detect the presence of sulphate reducing bacteria. A bacterial count (10 – 100 CFU/ ml) was observed from the untreated inoculated sample on the twenty fourth day indicating that biocide treatment is recommended, however no bacteria was detected from the treated inoculated sample after twenty eight days. Almost all the problems associated to injectivity impairment have to do with the quality of injection water. The physicochemical properties as well as the bacterial count of injection water affects the optimum performance of production equipment and reservoir formation by way of clogging, plugging of filters, reduction of pump efficiency, corrosion of pipes and bridging of reservoir pore spaces. All these are very instrumental to the productivity of the reservoir and the probability of causing these damages to equipment and formation is indicated by the silt density and plugging index.    Key Words:  Injectivity, inoculation, plugging, corrosion, deaeration, clogging.