Application of environmental process engineering for pollutants reduction and energy savings in crude oil production processes

Ngene, Stanley

Abstract

Crude oil production generates pollutants whose management require capital and recurrent investment in energy intensive treatment facilities. Produced water is the main pollutant and the volume generated increases as the oil wells get older. Benzene, toluene, lead, chromium, ammonia, naturally occurring radioactive materials and other compound s are found in produced water at levels higher than allowed by regulatory authorities thereby making the water toxic and raising the need for treatment prior to re use or disposal. The application of process integration techniques on the production process with targets set on energy savings and pollutants reduction allowed the manipulation of thermodynamic variables of temperature and pressure by the research as an alternative route to achieve the reduction of the concentrations of pollutants in produced wa ter to regulatory limit other than the deployment of the capital intensive produced water treatment technologies.

Several samples of produced water were collected over a cumulative period of twelve months at onshore and offshore crude oil production facilities. Data resulting from laboratory analysis of these samples and information on the process plants including but not limited to design and operating parameters were used as input in Aspen Hysys 8.8 process simulation software to test the hypothesis of the research. The study has applied results from the “laboratory - simulation - analysis” methodology to obtain results which indicate that temperature and pressure variation lead to decrease in the concentration of pollutants in produced water and subseque ntly savings in energy consumption of the production process. The change in concentration decreases across the production process. A temperature of 40 0 C 45 0 C and operating pressure at the WIJ pump of the IFS (onshore facility), causes decrease in the concentration of toluene, ammonia and nitrates by 2.28 x 10 3 mg l 1 o C 1 , 5.62 x10 1 mg l 1 o C 1 and 1.41 x10 2 mg l 1 o C 1 respectively. At the analyser exit of the offshore facility, a pressure of 20 30 psi and operating temperature causes the concentrations of toluene, phenol, lead, and chromium to reduce by 6.6 x 10 4 mg l 1 psi 1 , 2.86 x 10 3 mg l 1 psi 1 , 4.0 x 10 4 mg l 1 psi 1 and 5.0 x 10 4 mg l 1 psi 1 respectively. respectively. The best reduction in the concentration of pollutants was achieved by a combination of temperature and pressure at the line heater exit of the onshore facility and at the hydrocyclone inlet of the offshore facility. The concentrations in both cases were lower than the Nigeria oil industry’s regulatory limits. Moreover, an annual energy savings of about 379,600KWh and 64,984 KWh could be achieved at the offshore and onshore production facilities respectively. The implication of the research study is that if constituent equipment on the production facility are subjected to the temperature and pressure recommended by the research, the final produced water leaving the facility will be good for disposal without further treatment thereby saving cost and energy for the production process.

• Thesis Type: Thesis
• Deposit Date: Oct 4, 2019
• Publicly Available Date: Mar 17, 2020
• Public URL: https://uwe-repository.worktribe.com/output/3499915
• Award Date: Mar 17, 2020