William H. Thomason

Advanced Electrostatic Technologies for Dehydration of Heavy Oils

Effective oil/water separation continues to be a major challenge in heavy oil (HO) production operations and often involves high capital costs (large, heated vessels) and high operation costs (heat, fouling, upsets, chemicals). Application of new electrostatic dehydration technologies has the potential to have a major impact in reducing these costs. A systematic evaluation of four electrostatic dehydration technologies was performed using lab, bench scale, and pilot scale (40 gallons) testing. Four heavy oils ranging from 8 to 21 API were used. Performance criteria measured were effective emulsion separation rate (vessel throughput), separated oil and brine quality, water droplet size distribution for inlet and outlet emulsions, and comparison with field data (as available) for older electrostatic technologies. Traditional bottle tests were performed for reference. A 2 to 4 fold increase in emulsion treating rate was observed for some of the heavy oils using the newer electrostatic technologies relative to the traditional Alternating Current (AC) method with the same output quality of crude and brine. Relative cost data per barrel of emulsion processed were developed from system cost estimates and throughput data developed in the pilot tests. Treatment with acid to bring the separated brine into a 6 to 6.5 pH range had a very beneficial effect on the oil/water separation for some of the heavy oils with high TAN.

Evaluation of Aluminum-Sprayed Coatings for Corrosion Protection of Offshore Structures

Selection of an optimal corrosion protection method for offshore structural high-strength steel was necessary to avoid potential fatigue and hydrogen embrittlement problems. A study to evaluate the corrosion protection provided by sacrificial anodes and flame-sprayed aluminum coatings was undertaken. Reliability, availability, and influence on fracture and fatigue properties were the main factors considered in the study. The results illustrated that a properly applied flame-sprayed aluminum (FSA) coating represents the most viable scheme for providing long-life corrosion protection and improved corrosion fatigue and cracking resistance.