MAINTAINING WELL FACILITY HEALTH – THE APPLICATION OF DNA ANALYSIS TO CORROSION AND BIO-FOULING PREVENTION

摘要

Microbes can flourish in a wide range of environments and are also present in oil reservoirs, wells and topside facilities. They may constitute a massive threat to the well and facility integrity. For instance, bacteria and archaea may live in biofilms bound to metallic surfaces of the field’s infrastructure. By extracting nutrients from fluids, they trigger cathodic reactions, which leaches iron-ions from steel and cause a severe corrosion (Microbial Induced Corrosion: MIC). At the same time the corrosion products, the metabolic products and the biofilm build-ups may cause clogging of reservoirs, pipelines and filters, called ‘bio-fouling’. In numerous cases the changes in microbial populations are the cause of increase of corrosive and hazardous contaminants in the production fluids such as H2S and CO2 (souring). New advances in Molecular Microbiological Methods (MMM) using DNA technologies allow us to identify all species present in a sample. This is achieved by the Next Generation Sequencing (NGS) technologies. The advent of NGS and other MMMs has led to new insights, and the focus is now more towards identifying all microbial species, rather than quantifying specific groups, which was more common in the past. NGS has become a quick turn-around time and cost efficient technology, which allow microbial monitoring of reservoir and injection fluids in the oil and gas production process. The analysis of mineral and biological scale from wells and pipelines, filter residuals and drill cuttings in combination with isotope analysis and QEMSCAN mineralogy analysis facilitate the determination of the origin, location and severity of microbial contamination. The changes of the microbial populations are often an indication for the deterioration of the 'field health', which could occur in the reservoir, in the well bore or at the top-side facilities. The workflow presented here is therefore called a ‘health check’ and consists of establishing a ‘baseline’ and ‘microbial map’. Subsequently, a tailored monitoring analysis program can be defined in order to evaluate the success of mitigation activities. Based on the results of the monitoring analyses the mitigation and inhibition can be optimized, which lead to a better field health and facility integrity and significantly reduces repair costs and downtime.