For the past 8 years Chemiphase Ltd has been working on an environmental biological treatment process to reduce the presence of Hydrogen Sulphide (H2S) in crude oil production.

This biological “process” entails the natural and environmental production of specific micro-organisms which essentially utillize biological pathways to convert the Hydrogen Sulphide Gas/liquid to safe components like sulphate ions.

 “Biokatz H2S Treat Process”

This Process has been devised to control the presence of Hydrogen Sulphide and the micro-organisms that produce the H2S. How the process works, is relatively simple to describe.

Chemiphase has formulated a biological treatment that contains a range of micro-organism strains, classed in biological terms as “chemo-lithotrophiles” that are known to effectively oxidise H2S, in stages that ultimately will oxidise all sulphide ions present to soluble sulphates.

In order for these “chemo-lithotrophiles organisms” to continually control the variable concentrations of H2S in the crude oil there is a requirement to produce a continuous stream of bacteria product.

To ensure these bacteria populations are continuously created Chemiphase has designed & built a static bioreactor. This bio-reactor is capable of continually growing up the organisms, at the correct concentration through variable temperature and weather conditions.

The nature of these chemo-lithotrophic organisms can be best described as a facultative species, which means they are able to live in either aerobic (oxygen is present) or anaerobic (where no oxygen is present) conditions.

As a general rule the organisms will:

• Under Aerobic conditions, use oxygen to oxidise any H2S species present to a more oxidised species.

                          H₂S + 20₂                                            2H⁺ + SO₄^2-

     Hydrogen Sulphide   Oxygen             Hydrogen ions     Sulphate ions

• Under Anaerobic conditions use typical “oxygen donor“species that Chemiphase has added in the form of liquid nitrates or other nitrogen/carbon oxides to the bio-reactors nutrient package.

        5H₂S + 8N0₃              4N₂ + 5SO₄^2- + 4H₂O + 2H⁺

 Hydrogen Sulphide       Nitrate Nitrogen  Sulphate Water  Hydrogen ions

 Therefore by using the two processes above we have been able to create the essential environmental conditions that favour the “oxidizing conditions”.

Achieving this state of Oxidising will then allow the treatment organisms to slow down the “in-situ bacteria’s scenario of producing Hydrogen Sulphide”, and allow the treatment oxidizing bacteria process to grow and out compete the inherent SRB reducing bacteria populations.

 The “Oxidation products formed” with this treatment approach are:

• Sulphates (SO₄^2-)
• hydrogen radicals (2H⁺⁾
• And under Anoxic conditions free nitrogen and water. (4N_{2 +} 4H₂O)

 These environmentally safe oxidation bi-products are re-injected along with the collected “produced water stream” back into the reservoir via a dedicated water injection well.

 To Ensure our treatment process Continually reduces the presence of Hydrogen Sulphide the Bio-Reactor must run accordingly:

1. By adding the correct bio-nutrients and at the correct levels along with the specific chemo-lithotrophic microbial strains mentioned will alter the environment to suit our “Oxidising Conditions”
2. To Ensure the correct levels of both components above, we use a Bio-reactor, designed to maintain, good mixing capabilities, temperature control and an environment for nurturing the growth of our biological strains, to the desired treatment levels. So the chosen bioreactor conditions will create sufficiently large populations of the intended bacteria strains –please see notes on Bioreactor below
3. Finally by continuous dosing the produced bacteria stream from the bio-reactor to selected points within the “wells” engineering process will then show the reductions in Hydrogen Sulphide.

To Summarize the technical discussion:

Our “Biokatz H2S Treat”. biological process is particularly effective for combating H2S produced by Suphate Reducing Bacteria (SRB’s) since it is well known in nature and documented in many technical literature.

• That the speed of the oxidation process is considerably faster than of the anaerobic reduction process that produces the H2S.
• Normal conventional chemical scrubbing units are termed as stoichiometric reaction, meaning 1 kilo of H2S present will require 5 kilos of Scavenger to remove the 1 kilo of H2S. So High levels of H2S will result in very high levels of Scavenger. Resulting in high levels of Chemical Wastes
• The “Biokatz H2S Treat”. biological process is described as a non-stoichiometric process meaning -- it does not require specific amounts of bacteria present to oxidise current levels of H2S. ie. 1 kilo of bacteria to 1 kilo of H2S.
• The actual biological process of Oxidation of Hydrogen Sulphide to Sulphate ions is the following:

1. Sulphide (S^2-)
2. Sulphur    (S^{o )}
3. Thiosulphate (S₂O₃^2- )
4. Tetrathionate (S₄O₆^2- )

1. Sulphite   (SO₃^2- )  
2. Sulphate   (SO₃^2- )            

 THE BIOREACTOR PROCESS:

The bioreactor has altered dramatically over the 8 year period of dosing. From our continuous research we have been able to reduce the size of the system and increase the effectiveness many fold.

Part 2 The bio reactor consists of the following:

• Nutrient Dosing Unit:
  • A variable timed liquid Nutrient dosing system that is capable of adding nutrient to a bio mixing chamber when required.
  • The nutrient product CP-1055 is a specific blend of inorganic & organic additives as described in the Material safety data sheet attached.
  • Biological dosing Unit
    • A variable timed liquid Concentrated Biological dosing system that is capable of adding bacteria to a bio mixing chamber when required.
    • The Biological product CP-1055 is a specific blend of specific chemo-lithotrophic microbial strains as described in the Material safety data sheet attached.
    • Heating system that will control the mixing chamber’s temperature between 25-32 degC at all times
    • Fresh Water system that will add required fresh water make up to the mixing chamber when required
    • Aeration system that essentially ensures a dissolved oxygen level within the mixing chamber is achieved at all times.
    • Re-circulation system for the mixing chamber to ensure all contents are continuously mixed to achieve maximum contact between nutrients and bacteria for optimum growth rates. The bateria concentration prior to dosing the FWKO vessel is controlled between (1x10^6--1x10⁸⁾ Colonies per ml (millilitre)
    • Dosing Pump that will add a specific amount of timed bio reactor product to FWKO vessel. We are currently adding 3 tonnes per day of bio-product to the system on a timer basis.

The Oil/water production system details:

The production of oil is around 4500 BOPD (barrel of oil per day) which consists of produced and power fluid.

• The “produced Water” is around 2100 BWPD (barrel water per day) which is cleaned of oil and then re-injected.
• The dry oil and the biokatz treatment is then returned to the power fluid tank for re-injection down the oil wells.
• The “Biokatz H2S Treat” Stream is then transported down the well, the bacterial product will then coat all surfaces, due to their ability to reasonably motile i.e. Places where the bacteria will coat:
  • Pipe surfaces
  • Pump
  • Lip of the formation

 Results to date:

We believe the bioreactor is treating the varying H2s levels exceptionally well. The true effectiveness of the system as it is deployed at present can be judged from the H2S levels in the gas leg of the 1^st Stage Separator.

The results have clearly shown:

• During periods when the bacteria populations have not been injected into the separator, H2S levels can reach levels greater than 20 ppm (considered sour).
• All of the times when the bioreactor is in operation the H2S levels have been shown to remain relatively consistant.
• Effective operation of the system also results in a recognizable improvement in the odour in the vicinity of the separator.
• We believe the use of this “Biokatz H2S Treat” scavenging system” has extended the period of time between recharging of the Sulphatreat Towers and thus reduces overall levels of waste arising and associated replenishment costs.

SUMMARY:

In effect, use of a biological H2S scavenging system extends the period of time between recharging of the Sulphatreat towers and thus reduces overall levels of waste arising and associated replenishment costs.

The system also provides the opportunity to reduce the dosage rates of the more expensive chemical treatment H2S scavenger. Since the process is Environmental, proven to be cost effective and produces at least as benign wastes as the processes which it supports, we believe that it constitutes a Best Available Techniques polishing system.