David J. Blumer

Asphaltene Flocculation Onset Determinations for Heavy Crude Oil and Its Implications

Abstract The transport of heavy oils from the wellbore to the refinery is a costly process because heavy oils have high viscosities, which result in higher energy requirements in pumping. Producers have used large quantities of diluents to reduce the viscosity and make the heavy oils more pumpable. However, the addition of diluents might precipitate asphaltenes from the heavy oil and cause plugging and fouling problems. The asphaltene flocculation onset titration is often used to predict asphaltene precipitation tendency of crude/diluent mixture. In this article we present work performed on a Venezuelan heavy crude where the asphaltene flocculation onset was extrapolated for the dead crude using a solvent dilution method. Flocculation point measurements under high pressure utilizing a high-pressure cell with the solid detection system (SDS) were also conducted. The data show good correlation between the high-pressure titration experiments and solvent dilution method using dead crude oils. The data predicted the range of diluent addition for which asphaltene precipitation and flocculation problems could be encountered in the field.

A Novel Method to Mitigate the Top-of-the-Line Corrosion in Wet Gas Pipelines by Corrosion Inhibitor within a Foam Matrix

Top-of-the-line corrosion (TLC) has been a serious issue for the oil and gas industry. Conventional inhibition techniques are expensive and often do not seem to provide enough protection to the steel surface at the top of the pipe. A novel idea is to inject the corrosion inhibitor within a foam matrix. The foam slug is formed first at an injection port and carried along the pipe by the gas phase. This process ensures homogeneous delivery of the inhibitor to the pipe wall along pipe sections suffering from TLC. This paper presents a comprehensive study performed in an innovative glass cell setup which consisted of a foaming cell and a corrosion cell to simulate intermittent contact between the foam and the steel surface. Corrosion measurements were performed using electrochemical techniques (electrochemical impedance spectroscopy [EIS], linear polarization resistance [LPR], potentiodynamic sweep) and electrical resistance (ER) measurements to determine the inhibitive performance of investigated inhibitor t...

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.

Evaluating Corrosion Inhibitors For Sour Gas Subsea Pipelines

Using subsea carbon steel pipelines to transport wet sour gas possesses huge challenges to the operators to maintain the high level of the Assets and Operating Integrity. In many cases, carbon steel is still the primary choice for the subsea pipeline material.