Environmental SRB Treatment

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An oil well is a complex ecosystem that contains a number of bacterial and microbacterial components that can impact oil production. Two important bacterial types are Sulphate Reducing Bacteria and Nitrate Reducing Bacteria.

An Environmental Approach for SRB Control - Sulphate Reducing Bacteria and Nitrate Reducing Bacteria in Oilwells

An oil well is a complex ecosystem that contains a number of bacterial and microbacterial components that can impact oil production. Two important bacterial types are Sulphate Reducing Bacteria and Nitrate Reducing Bacteria. 

Many bacteria reduce small amounts of sulfates in order to synthesize sculpture containing cell components; this is known as assimilatory sulfate reduction. By contrast, the sulfate-reducing bacteria (SRB) considered here reduce sulfate in large amounts to obtain energy and expel the resulting sulfide as waste; this is known as dissimilatory sulfate reduction. They use sulfate as the terminal electron acceptor of their electron transport chain and produce hydrogen sulphide (H2S) as the waste gas product. Most sulfate-reducing bacteria can also reduce other oxidized inorganic sulfur compounds, such as sulfite, thiosulfite, or elemental sulfur (which is also reduced to sulfide as hydrogen sulphide).

Nitrate Reducing Bacteria (NRB) consist of two specifc types of Bacteria. NR-SOB’s (Nitrate Reducing Sulphidde Oxdising Bacteria) and hNRB (Hetertrophic Nitrate Reducing Bacteria). NR-SOB’s directly oxidize H2S, eliminating its presence within the oil well, whilst hNRB’s  compete with SRBS for degradable organics for synthesis.

The hNRBS reduce the amount of SRBs present within the well by actively competing for degradable organics that can be used for synthesis. This means that the SRB numbers will be lessened, as there is essentially a ‘food shortage,’ due to the activity of the hNRB, resulting in a reduction in SRB multiplication and activity.

The NR-SOB’s use H2S gas for synthesis, oxidising this gas. In this way they actively reduce H2S levels by removing it from the downhole environment.

The Chemiphase treatment involves the introduction, stimulation and cultivation of the NRB’s in order to effectively manage H2S problems.

Firstly the product introduces and stimulates the growth of NRBs. In essence, the microbial community is changed from one that is abundant with SRBs to one that is abundant with NRB’s. Secondly, cultivation of the NRBS through a supply of suitable, specific nutrients enable the NR-SOB’s  to directly oxidize H2S, meaning a significant decrease in the levels of hydrogen sulphide present in the well and thus reduction in the issues which accompany high H2S levels.

Bacterial Contamination Testing

Not all oil wells will contain SRB’s and even very close, communicating wells can see differing levels of bacterial activity. It is necessary, before carrying out an NRB treatment programme to establish the level of SRB contamination (if indeed there is any).

In order to test for SRB contamination a sample of fluid is taken from the well to be tested and introduced to a test tube. These test tubes contain a selective microbial culture medium that semi quantitatively indicates the presence of SRBs, by the rate and extent of a colour change on the culture medium. The test tubes are incubated at a constant temperature for five days, with periodic recordings of the colour change and extent of colour change, taken.

 The tests are independently supplied and are calibrated against the Standard Test Method for SRB, NACE TMO-194-94 using API medium. 

Product Name            

Product Description 

Product Code

CWS 1122 Biological SRB Treatment                            CWS1122-1000


All our chemical ranges are formulated by our highly trained and vastly experienced chemists and are put through rigorous in house testing in our purpose built research and development laboratory. We subject our chemical ranges to the most stringent of testing to make sure our customers receive the best products, whilst also satisfying our need for constant product improvement.

Once the products have met our exacting standards, we move on to our modern production facility where our skilled technicians produce each and every product to the same precise formulations, before they are shipped on to you, our customers.

For more information on the products please see product data sheets below.