Novel Viscosity Reduction System Allows Heavy Oil to be Transported in Conventional Pipelines
Mike Crabtree (mikecrabtree@advancedgel.com), Managing Director, Advanced Gel Technology Oil (http://www.advancedgel.com) discusses a new additive, known as a hydrogel, which can be mixed with heavy oil to reduce its viscosity. The chemistry uses polymers cross linked with a proprietary chemical that gives products with unique properties. The main applications are in pipeline transportation of heavy crudes and for sub-surface artificial lift of heavy oil. The technology behind the product known as Proflux TM is based on technology invented at Bradford University.
The Technology
The system typically uses 30% of the Proflux product and 70% heavy oil to form a dispersion with unique properties (Figure 1).
Figure1: Schematic of Heavy Oil in Hydrogel Dispersion
Using the system, heavy oil viscosity is reduced by a factor of up to 60. Figure 2 shows a heavy oil with a viscosity at 200 s-1 of 12,500 cP reduced to 200 cP by the chemical additive. This reduction allows the oil to be pumped through conventional crude oil transport pipelines. The chemical is effective on heavy oils with viscosities ranging from 100 cP to 70,000 cP at 25°C. The proportion of additive to heavy oil can be varied depending upon the conditions and the dispersion rheology required.
Figure 2: Viscosity Reduction of Heavy Crude with Addition of Proflux Product
The key operational feature is that the heavy oil dispersion can be made, transported and dehydrated all at ambient temperature. This means that the heavy oil at the pipeline destination can be completely restored for processing or further transport. In addition for most applications, the chemical additive can be separated from the heavy oil and re-used, further increasing the cost effectiveness of the system.
The Proflux material is environmentally friendly and falls within the lowest toxicity category for oilfield chemicals.
Field Applications
The principal applications of the product are in the pipeline transportation of heavy crudes (Figure 3) and in sub-surface artificial lift of heavy oils (Figure 4). The additive gives an order of magnitude reduction in the pumping pressure losses though the pipeline. Economic modelling of a number of projects has shown that the product offers the most cost effective solution to heavy oil transport in terms of both Capex and Opex costs. For artificial lift the chemical can be injected into the bottom of the tubing to reduce the viscosity of the heavy oil in the well allowing increased oil production and reduced well costs though the use of smaller, more efficient pumps. The product is separated from the oil at the surface, re-cycled and re-injected into the well. This promises a highly cost-effective method for significantly increasing the performance of heavy oil wells.
Figure 3: Heavy Oil Viscosity Reduction for Pipeline Applications
Figure 4: Use of Proflux for Artificial Lift in Heavy Oil Wells