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RESERVOIR SOURING MODELLING

Prediction, monitoring and mitigation / prevention

The souring research project, managed by Oil Plus, has led to development of specialised industry software that can predict souring potential for the life-span of a field.

Oilfield reservoir souring prediction, mitigation and management programmes using data gathered from on-site fluid analysis, laboratory testing and input into specialised computer modelling simulations.

Reservoir souring is a process in which a previously sweet oilfield (i.e. one which contains no H2S) begins to produce fluids containing H2S generated by microbiological activity. It typically occurs in reservoirs flooded by sea water for pressure maintenance or secondary oil recovery, as a result of the introduction of sulphate-rich injection water containing sulphate-reducing microorganisms into nutrient-rich formation water. Problems caused by reservoir souring include:

  • Increased general corrosion risk and sulphide stress cracking (SSC) in production tubulars, risers, topside vessels and pipelines, as H2S is highly corrosive
  • Increased HSE concerns as H2S is highly toxic
  • Increased OPEX – due to H2S scavenger use
  • Increased CAPEX – due to selection of corrosion resistant alloys (CRA) or lining of pipelines
  • Disposal of large amounts of toxic spent H2S scavenger
  • Reduced value of oil and gas containing H2S

Oil Plus specialises in the understanding of production issues related to souring and their mitigation. Effective and accurate prediction of biogenic reservoir souring potential using comprehensive computer based modelling tools is essential when undertaking major techno-economic decisions regarding field development and material selection. The ability to recreate the essential environment necessary for generation, transportation and account for the mechanism of souring in a model, hugely affects prediction accuracy. Oil Plus provides expertise in this area and, uses comprehensive 2D and 3D souring modelling tools that incorporate all the above factors and more.

The 2D model is a finite difference flow simulator developed as part of a Joint Industry Project (JIP) which models single well pair scenarios and has been applied in various projects for effective souring history-matching and predictive forecasting.

Laboratory and field based research to investigate and continually improve reservoir souring simulation and control, as part of a JIP, has been carried out over several years and is on-going, with Oil Plus at the forefront of this research. This research programme has led to the development of the world’s foremost reservoir souring predictive modelling tool, SourSim®RL. The software has been developed with full 3D transient capability, which implies, the souring solution is solved by coupling with the reservoir simulator to incorporate the full 3D transient. Thus, reservoir parameters, fluid flow dynamics and well operating conditions provided by the reservoir simulator are brought into the souring simulator to provide the final souring solution. Additionally, SourSim®RL has the added capability of coupling to several industry standard reservoir simulators available in the market.

Oil Plus’s comprehensive predictive souring modelling capability enables our customers to plan process equipment requirements and production operations at the start-up stage of a green-field as well as helping control/limit reservoir souring in brown-field developments. In many producing assets effective monitoring of the produced fluids as well as onward quick reaction of the on-site operation teams are important to detect the onset of any potential H2S production and help set up specific follow-on management programmes to that field in order to prevent further escalation of the souring threat.

In addition, Oil Plus provides assistance to operators supporting their staff on both a short-term and long-term basis in achieving process optimisation.