Oil Reservoir Souring

Preventing reservoir souring is essential to maintain the value of oil reservoirs and fight corrosion in pipelines. See how PetroCare helps.

Every day, the leading oil service companies rely on Yara’s PetroCare to control biological hydrogen sulphide (H₂S) formation, prevent acidification in the oil tank, and to optimise drilling fluids.

Why PetroCare? 

PetroCare works by preventing the biological formation of H₂S, through stimulation of natural processes. It is an environmentally friendly solution in comparison with alternatives available on the market.

  • PetroCare offers the benefits of Yara’s extensive experience of controlling H₂S in industrial processes and wastewater treatment plants worldwide.
  • You can expect consistent high quality thanks to our experience gained as the world leader in the production of nitrates.
  • PetroCare can be delivered around the world in liquid or solid form. Yara supplies in IBC, flexiliner, container or ISO container.

Combat oil reservoir souring with PetroCare

Yara's H₂S reduction solutions for the oil industry: 

  • Prevent and mitigate biological souring
  • Fight corrosion in pipelines
  • Improve safety for the workforce

Independent academic reports, laboratory and field tests recommend nitrates to reduce H₂S formation and help improve work safety.

What causes oil reservoir souring?

Biological reservoir souring happens when water injection is used for secondary oil recovery, especially in offshore installations where sulphate-rich seawater is used. The lack of oxygen, warm temperatures and the presence of sulphate, stimulates naturally-occurring microbes, which then produce toxic H₂S. This turns sweet oil to sour.

Sour oil has a lower market value and the presence of H₂S gas at the producer can lead to:

  • Material damage (MIC corrosion)  
  • Restricted production rates  
  • Serious occupational health issues 

How PetroCare works 

PetroCare is dosed into the injected seawater. This encourages the microbes to generate harmless nitrogen gas – instead of the harmful sulphide produced when sour conditions prevail.

Specialty nitrates like PetroCare change the bacterial environment, so that they no longer produce sulphide gases. Nitrate is a natural substance present in soil, where it is a major nutrient for plants. Yara’s nitrate-based technology is, therefore, a natural, environmentally friendly way to eliminate the problems caused by H₂S.

PetroCare for drilling fluids 

Selection of an acceptable drilling fluid is now increasingly linked to environmental legislation on waste management, cost savings, as well as traditional technical aspects. Disposal of waste drilling fluids and associated contamination is becoming a concern worldwide.  

Operators adapt by developing and following waste minimization, recycling and bioremediation strategies. In addition the right choice of drilling fluid will increase Rate of Penetration (ROP) of the bit and therefore total drilling depth is increased. These are some of the reasons why the leading oil service companies have come to rely on Yara’s environmentally-friendly PetroCare in drilling fluid.

Yara’s knowledge of nitrates has allowed our experts to develop speciality nitrates that can be added to drilling mud (fluid).

Espen Langerød
Espen Langerød
Sales Manager

If you want help with combatting biological reservoir souring or a quote for PetroCare to use in drilling fluids, contact us.

Uses for PetroCare in drilling fluids


PetroCare replaces calcium chloride, sodium bromide or formate salts in the internal phase. It provides an environmentally friendly solution and reduces waste management issues and related costs. The wide range density PetroCare offers also gives operators the flexibility to use it as mid-range density brine.

Clear brine solution

PetroCare can be used as an inorganic flocculant. This application is linked to reactive clays with a high rate of penetration (ROP). Using it this way prevents bit balling and flowline plugging. PetroCare contains calcium nitrate, which is classified as a "medium clay inhibitor". Water resulting from dewatering process can be used as a base for preparing other mud systems.

Fracturating fluids

PetroCare acts as an inhibitor of sulphate-reducing bacteria during fracturing processes. Speciality nitrates are added, in addition to biocide products. Biocide is included to protect guar gum and reduce biofilms.

Cementing job

PetroCare can be used as cementing additives to help operators meet strict criteria of thickening time in cementing jobs including steam-injection slurries. PetroCare cementing additives increase the early compressive strength (up to 8 hours) and decrease wait on cement (WOC) time reaching 50 and 500 psi.

The use of PetroCare cementing additives drastically reduce slurry sedimentation, free fluid and cement fall-back. In addition, the overall well safety, well integrity and quality of cement job can be improved and eventually demand for any remedial job reduced.

Clorin fluid tracer

Thanks to PetroCare, you can determine the presence and extent of possible damage of core samples by invasion of the mud or filtrate from the mud.

Liquid and solid waste where PetroCare has been used can offer a greener solution for waste disposal. For example, Canada has a program for using bioremediation techniques (land farming) to help deal with waste soil by creating various conditions to stimulate aerobic microbial activity. Using Calcium Nitrate in place of calcium chloride offers several advantages: 

  • Lower acreage required to spread the same volume of waste.
  • Nitrate acts to biodegrade any oil left on cuttings and enrich the soil.
  • Removes the need to add additional nutrients to remineralize the soil.

Nitrates can stimulate bio-reactors used to process waste materials and therefore give a higher output from the process.

Why choose PetroCare from Yara?

Oil platform

Used by leading oil companies

PetroCare is used worldwide and has been chosen by a number of oil companies as their main souring mitigation strategy for oil fields in the North Sea, Latin America, the Gulf of Mexico, off the coast of West Africa, Russia and the Far East.

Oil platform

Proven technology against souring

Published case reports show that where nitrate is applied correctly it can provide a good preventative/ mitigation strategy for H₂S generation, improved worker safety and for souring control.

Reliability of supply

Reliability of supply

Expect reliable deliveries thanks to Yara's global logistics network, with more than 200 terminals and warehouses around the world. Depend on consistent high-quality thanks to our experience gained as the world leader in nitrate production.

Liquid or solid

Liquid or solid

PetroCare can be delivered around the world in liquid or solid form – so you can choose the form that suits you best. Yara supplies anywhere round the world in IBC, flexiliner, container or ISO container.