(383e) Investigating the SI Hydrate Crystal Formation at Different Produced Water Levels for Offshore Flow Assurance

As the oil fields mature, the amount of produced water increases. The excess water production is likely to lead to problems such as corrosion, gas hydrate formation, salt deposition, and water disposal issues. Gas hydrate is ice-like crystalline compounds that are formed under high pressure and low-temperature conditions in the sub-sea lines causing an unwanted blockages and safety threat to close by operators. Annually, the industry spends about 1 billion US $ on the prevention of gas hydrates and they are considered to be a major flow assurance concern for the oil and gas sector. In order to prevent the hydrate formation the industry heavily relies on the use of chemical inhibitors such as thermodynamic hydrate inhibitors and kinetic hydrate inhibitors. These inhibitors are injected into the pipeline and they function by shifting hydrate vapor-liquid equilibrium to lower temperature values or by delaying the hydrate formation time. The amount of water present in the subsea lines is likely to affect the performance of these chemical inhibitors and depending on the level of water present the dosage of the inhibitor may need to be altered. So the aim of this project is to investigate the hydrate SI crystal formation at different water levels and see the effect of different water levels on the performance of selected gas hydrate inhibitors.

A series of experiments were conducted under different pressure conditions (40-100 bars) using rocking cell assembly (RC-5) and pure methane gas. The RC-5 mimics a subsea line and can be operated up to 200 bars with a temperature range of -10 ^o C to 60 ^o C. The inhibition performance of selected eco-friendly hydrate inhibitors was evaluated at different water levels and the amount of hydrate formation that occurs at each water level was estimated. According to the preliminary experimental results, the different water levels do have an effect on the amount of hydrates produced and the inhibition performance of selected hydrate inhibitors. This work is highly beneficial for the oil and gas sector as the hydrate formation at different water levels has been examined along with the performance evaluation of the hydrate inhibitors at different water levels. This will help the industry to optimize their inhibitors dosages, reduce their operating cost and assure smooth energy transfer.

About Authors:

Prof. Majeda Khraisheh and Dr. Fahed Qureshi are active researchers in the area of flow assurance. Their work focuses primarily on applied research in the area gas hydrates considering the offshore industrial needs and addressing the environmental constraints associated with commercial hydrate inhibitors. They can be reached at m.khraisheh@qu.edu.qa and fahed.qureshi@yahoo.com .