Monitoring Oil Content In the Produced Water From the Usinsk Oil Field By IR-spectroscopic Methods
Authors: Tskhadaya N. , Medvedev V. , Dorfman M. 
Published: March 2010

Results are presented for determination of oil contaminants in produced water from the first-stage separation unit, Usinsk Oil Cleaning Plant. De-watered stock tank oil is delivered to the main oil pipeline for delivery to consumers. The produced water is delivered to the Formation Pressure Maintenance System (FMPS) and injected back into the productive formations. Water: quality control is important for economic reasons, with elimination of sulphate-reducing microorganisms the most important.

Technological Plan of Treatment of Oil and Produced Water

Usinsk Oil Cleaning Plant (UOCP) treats oil/water emulsion from some oilfields (Usa, Vozey, Khariaga). There are central batteries for treatment of oil/water emulsion in Usa and Vozey oilfields. Dehydrated oil from Vozey oilfield is pumped into the Khariaga-UOCP pipeline, through which oil/water emulsion (70% water content) is transported from the oilfield. Water treatment is not available in Khariaga oilfield. Dehydrated water from Usa field gets into this pipeline before coming to the UOCP. The average water content in oil/water emulsion is 40 - 50%; the average temperature of oil/water emulsion is 17– 20?C. The capacity of the UOCP is 14 million tons of emulsion a year. Technology of Table 1: Sample results. Available In Full Paper oil treatment includes heating, dehydrating, and treatment. There are two technological treatment units referred to as "Usa" and "Vozey." Because of the shortage of emulsion coming to the plant, only the Vozey unit operates. The Usa unit is used only for secondary treatment of produced water and crack. Treated oil is transferred to the coverage tanks and further to the main Usinsk-Ulchta pipeline. After treated at the treatment plant, produced water goes to the Formation Pressure Maintenance System. A schematic diagram of water treatment with sample points is shown in Figure 3.

FIGURE 1: Technological diagram of separation Unit "Usa." Available In Full Paper.

FIGURE 2: Technological diagram of separation unit "Vozey." Available In Full Paper.

FIGURE 3: Technological diagram water treatment plant. Available In Full Paper.

Sample Points

Samples were taken from Separation Units (SU) Vozey and Usa as follows:Water discharge from SU Vozey and UsaWater discharge from SU Vozey to storage tanksWater effluent from SU Vozey storage tanksWater effluent from SU Vozey, storage tank 4Water delivery to FMPS from SU VozeyWater delivery to FMPS from SU VozeyWater delivery to FMPS from SU Usa

The intent was to monitor water quality from SU discharge to FMPS injection. Analyses were performed in October 1993.

Analysis Method

The IR-spectroscopy method used to evaluate water contaminants extracted with carbon tetrachloride, developed by the authors, is similar to the photometric method for oil content determination in secondary waste waters (temporarily accepted). The procedure uses industrial equipment, which measures concentration in extract at frequency 2,900/cm, corresponding to methane, ethane and propane. The industrial device is calibrated with standard carbon tetrachloride solutions. The procedure permits accurate evaluation of both quantity and type of hydrocarbons. To measure IR spectra, a standard two-beam spectrophotometer ("Specord") was used. This equipment is compatible with the logarithmeter used to recalculate IR (T) spectra into optic density CD) spectra.