Recovery of Standed Gas: Solco TEPS - Total Energy Preservation System
Authors: Soland Arne , Mellerud Lars 
Published: October 2008

Since 1987 Solco has been developing the TEPS - a facility for offshore oil production and conversion of associated gas to methanol. Syncrude, LNG, and carbon black processes was considered and rejected.

The TEPS is a mature project. The process plant for methanol is based on low temperature and pressure technologies, utilising only steam in the reforming process. Pure O2 utilisation is avoided by safety and economical reasons. All components of the methanol plant that enable the TEPS development, have now experienced long term durable operation onshore. The process plant for oil/water/gas has been tested onboard the APTV Crystal Sea since dec. 94. A comprehensive design and verification process covering all aspects within HES, technology and commercial viability has been performed.

The TEPS is a low emission alternative. Solco is presently working on technology for further CO2 reduction from todays 460 Kg/ton MeOH.

On remote located fields, where the gas may have no value, TEPS is especial applicable. The TEPS concept enables a tripled gas value compared to gas export trough pipline, and opens for a commersial utilisation of stranded gas. The TEPS vessel is based on flexible compact modularised technology. The plants are designed for varying gas compositions, oil gravities and water content, which implies that a TEPS can be operated on consecutive fields. All systems are insensitive to ship motions.

Gas and water are the only feedstocks, thus eliminating hazardous oxygen onboard.

Compared to alternative technology for gas conversion, conversion to methanol offers a more compact technology, and more efficient process with lower emission than alternative conversion to synthetic crude oil. Typical payback schedule is 2.26 years based on incremental cost calculations. Gas consumption is 770 m3/ton inclusive power production for the vessel.

As TEPS will enable the industry to increase net profits versus decreasing pollution and also improve energy management, it can best be described as a quantum leap. Major car manufacturers have announced mass production of fuelcell operated vehicles, where methanol will be the fuel, within 3 – 5 years. The fact that the environmental friendly production of plastics through MTO - Methanol To Olefines process is now available, indicates sharp increases in demand for inexpensive methanol. TEPS can provide methanol at prices well within the required ranges.

Background Of Development

During the last decade the international community has increasingly focused upon the wasteful and pollutive management of resources, as exemplified by the flaring of associated stranded gas from oilfields. In attempts to reduce the pollution, and also in some instances as pressure support for production of oil, reinjection of the gas back to the reservoir has been widely developed. In most cases however, the result tends to be detrimental to the tail end of oil production, as the Gas Oil Ratio - GOR becomes too high for efficient separation in the installed process facilities. Due to the fact that the same gas is repeatedly compressed for reinjection, the result is quite often that more than 50% of the gas has been utilised for production of the necessary power for this purpose. Thus the result is that the gas is still subject to extended flaring. The Norwegian government has taken this into account, and imposed a very high CO2 penalty tax as a means to reduce this. In the UK similar legislation is being debated, and after Kyoto, there are reasons to believe that the rest of the world will follow such a pattern.