Preventative Safety Management Supported by an Emergency Response System for Sour Gas Production in North Germany
Authors: Grossmann Udo M. , Schoenbach Hartwig C. 
Published: December 2007

In general, the onshore production of oil and gas in North Germany takes place in densely populated areas. Approximately 800 MMSCFD of gas are produced from sour gas reservoirs, with H2S-concentrations of up to 20 Vol.-% being involved. Despite a high technical safety standard and different organizational measures in the production of sour gas, emergency cases cannot be absolutely ruled out. An accidental sour gas release can cause health problems even if inhaled at low concentrations. H2S concentrations of more than 700 ppm will cause immediate death.

In Germany the production of hydrocarbons is regulated by the Federal Mining Law. According to these regulations an extensive gas protection plan and gas alarm plan have to be set up for sour gas operations. This includes establishing an emergency response organization and a gas alarm management guide.

Beyond the legal requirements Mobil Erdgas-Erdoel GmbH (MEEG) has implemented an emergency response management system in compliance with Mobil Oil's worldwide safety philosophy to minimize the risk for the population, the employees and the environment. The installation of two electronic data systems enables the crisis management team to respond faster, more safely and in a less complicated manner to accidental sour gas releases. The introduction of the Emergency Information and Response System (EMIS) makes possible the display and manipulation of maps in different scales and geographically oriented data. The expansion of the process master computer by installing an H2S-Gas alarm system has achieved the online measurements of H2S concentrations, wind direction and wind velocity at sour gas production facilities. The system, which is operated at the gas dispatcher center, gives the crisis response team the opportunity to predict the location of sour gas release and the area being impacted. Consequently rescue parties will be directed to the location in a safe manner and, if necessary, measures will be managed for evacuating the residents living in the danger zones around sour gas facilities.

Introduction

The onshore production of sweet and sour gas in North Germany takes place in generally densely populated regions. Among others MEEG operates sour gas fields in the State of Lower Saxony. The production areas of the Scholen concession are located between the cities of Hanover and Bremen (Figure 1).

Joint venture partner of the Scholen concession is BEB Erdgas and Erdoel GmbH (50 % Shell and 50 % Exxon). More than 50 billion cubic metres of sour gas have been produced, transported and purified in this area since 1963. Today, sour gas is produced from 12 main reservoirs with an infrastructure of 35 production wells, 9 booster compressor stations and more than 100 km of sour gas pipeline network (Table 1). The sour gas is purified at the MEEG operated purification plant Norddeutsche Erdgas-Aufbereitungs-GmbH (NEAG). After conditioning of the treated gas to sales gas specifications the sweet gas is fed into the sales gas pipeline network. All gas production as well as the gas conditioning process is managed by MEEG's dispatcher center.

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