Ohio University

Water Wetting Joint Industry Project

Internal corrosion of oil and gas wells and pipelines made of carbon steel is associated with the presence of water on the pipe surface, a scenario known as water wetting. When the circumference of the pipe is fully coated with oil, corrosion will not occur. Increased knowledge of water wetting and predictive capabilities can increase the confidence of the corrosion engineers and operators on the integrity of pipelines and can decrease the cost associated with corrosion mitigation.

The factors that contribute to water wetting in pipelines are both hydrodynamic and chemical. In general, higher oil flow rates and heavier oils will have a lesser tendency for water wetting. On the other hand, low oil flow rates, light oils, and large diameter pipelines are associated with a greater tendency for water wetting. Furthermore, surface active components from the oil, either naturally occurring or added as inhibitors, can alter the wettability of the steel surface, so that it’s less likely to be wetted with water, even under less desirable hydrodynamic circumstances.

Deliverables

  • Improved understanding of water wetting and the key factors affecting it.
  • State-of-the-art predictive model of water wetting in oil/water two-phase and gas/oil/water three-phase flows pipe flows.
  • Design and development of small scale benchtop devices for phase wettability tests.
  • Customized phase wettability assessment for specific crude oils.
  • Reports documenting results, analysis and outlining future work.
  • Database of water wetting and multiphase flow data which can be made available to others under special agreement.

Papers

Please contact Luciano Paolinelli for more information on the TLC-JIP.

Wettability Studies

The Institute for Corrosion and Multiphase Technology has built an extensive knowledge of the water wetting phenomena, starting in 2004. Current research emphasizes three-phase, oil-water-gas flow. The introduction of the third phase (gas) has a tremendous effect on the distribution of liquids on the pipe circumference and impacts water wetting. Knowledge of the wettability in three-phase flow has special importance since gas is usually present in wells, production flow lines, and risers.

In order to investigate multiphase flows, the Institute employs an instrumented 4-inch ID inclinable flow loop which allows for studies on horizontal, inclined or vertical orientation, in both upwards and downwards flows (Figure 1). Phase wettability is assessed using conductivity probes, which detect the conductivity of the fluid present at the steel surface. We take complementary relevant measurements such as characterization of flow patterns (visualization through a clear section using high-speed video), pressure drop (manometers and differential pressure transducers), phase distribution (impedance traversing sensor, impedance tomography, fluid sampling), dispersed water droplet sizes (particle video imaging and video endoscopy), and corrosion rate (electric resistance probes and custom-designed probes).

Small-scale benchtop devices have been developed and tested in order to study water wetting in flow conditions. These devices have been based on a shear-driven annular flow concept and proved to be very useful for studies on entrainment of water layers in two-phase oil-water flows using reduced volumes of oil (as low as two gallons). Phase wetting assessments on crude oil-water systems become to be much quicker and much less expensive with these devices.

Wetting characteristics of carbon steel surfaces in specific oil-water environments are also studied by means of contact angle technique (water-in-oil and oil-in-water) using a goniometer with video capability. Electrochemical studies are also performed in conventional glass cells and other flow cells to determine if surface active components from the oil can have an impact on the persistence of oil films.

All the obtained experimental data is employed to build and validate physical models to predict phase wetting at the internal pipe walls of multiphase flow lines (water wetting model). The development of the water wetting model is also assisted by computational fluid dynamic (CFD) studies.