Oilfield and Industrial Applications

How the Basic SWR Formula Works

The SWR systems are made up of powerful, water-activated surfactants.  These formulations are notable in three major respects:

1. They have a very high affinity for water (a high hydrophilicity) and will extract and dissolve it selectively from oil-water emulsions and mixtures.
   
   
2. They are highly oil-repellent or oleophobic and strongly promote separation of oil from oily sludges and residues.  This results in part from the high surface energy that exists at the SWR/oil interface.
   
   
3. They are unusually strong surfactants and preferentially absorb on to metal and other (e.g., concrete) surfaces and in doing so (a) displace dirt and oil residues that are present and (b) leave behind a very thin, protective and paintable inorganic coating, even after washing.

In combination, these properties result in SWR's outstanding cleaning capability.  Oily residues, which are typically oil or oil/water mixtures contaminated with solids, are immediately separated by settling into three components - an oil and grease layer floating on the top, a recyclable, reusable SWR system in the middle and an oil-free solid residue on the bottom.  These three components are thus easily separated.  The SWR can be repeatedly re-used until it has biodegraded sufficiently to lose effectiveness - typically for 30-45 days.

Oil and dirt are easily removed in even the most challenging cleaning applications and the oil and dirt easily separated - or even recovered - by settling and skimming off the hydrocarbon layer, then filtering the SWR to remove particulate matter.

In addition to their biodegradability (in 30-45 days under most normal use conditions), SWR systems are nontoxic, nonflammable and have proven to be environmentally safe through all standard state and federal testing procedures.  SWR has received SNAP approval from the U.S. Environmental Protection Agency.

SWR

What is it?

SWR is a surfactant system which exhibits a combination of characteristics that are not found in any comparable commercially-available system.  It is biodegradable, non-flammable, non-toxic at use concentrations and, unlike almost all other surfactant systems, is both hydrophilic (water-attracting) and oleophobic (oil-repelling).  It thus offers excellent emulsion-breaking capability in addition to its outstanding performance as an agent for cleaning both metallic and non-metallic surfaces.  It is this unusual combination of  properties that makes it so attractive for such a broad range of oilfield and industrial applications. 

Characteristics and Uses

1.  Cleaning, Oil and Dirt Removal

The excellent surfactant and detergent properties of SWR result in removal of even the most resistant oil and grease deposits.  The SWR system operates by preferentially absorbing on the surface to be cleaned, displacing the previously existing deposits of oil, dirt and other contaminants.  Heavy or baked-on oil deposits stripped from the surface are reduced in viscosity, or liquefied by a proprietary mechanism, and float to the surface of the SWR solution.  Particulate matter and loose or lightly adherent scale is stripped of oil (and stripped from the surface) and sinks to the bottom.  A clean surface, protected by a micro-thin inorganic film, remains.  As a result of its combination of hydrophilic and oleophobic behavior, the SWR system strips any water from the oil so that excellent separation can be achieved.  The SWR can be reused until its effectiveness is reduced by biodegradation, usually after 30-45 days.

2.      Scale Removal and Inhibition

SWR has proven itself useful in oilfield applications as an agent for the removal of the carbonate scales commonly found in pipelines, fittings, pumps and submerged equipment.  The scale is typically derived from formation or cooling water.  The SWR System strips out of the scale the organic content that typically holds it together, leaving a loose deposit that is easily removed by re-establishing normal pipeline flow.

Injection of the SWR System into the water phase in pipeline and water handling systems that are subject to scaling will, by the same mechanism, inhibit scale formation.  The scale compounds may instead form as suspended solids or not precipitate at all.

3.      Corrosion Inhibition

The basic SWR formulation provides modest corrosion inhibition by depositing a very thin but tightly-bonded inorganic film on the metal surfaces to which it is exposed.  In addition, if the corrosion is microbial in origin (e.g., sulfide corrosion caused by anaerobic bacteria), the antibacterial action of SWR can reduce this markedly. 

4.      Interfacial Tension Control: Emulsion Breaking

SWR injected into produced fluids that are flowing to wash or storage vessels increases the surface energy at the oil/water interface and thus helps to break emulsions of all types into distinctly separate layers of oil and SWR-bearing water.  Any particulate in the incoming fluid is dropped out and all water present in the oil is absorbed into the SWR-containing water layer.  Any waxy solids are typically returned to the oil phase.  Any bacterial action in the produced fluid is sharply inhibited. 

As a consequence of the use of SWR in this application, excessive use of conventional emulsion breakers can be avoided.  Water drop-out is often acceptable with just the SWR treatment alone, or with a greatly-reduced (typically one-third) level of emulsion breaker.  In addition, because many emulsion breakers contain high levels of known or potential carcinogenic aromatic solvents such as benzene, toluene or xylene, their presence in the waste water from production operations presents serious disposal problems.  They can be used at greatly reduced levels or even eliminated entirely by using SWR.

5.      Paraffin (Wax) Control

One of the most interesting characteristics of SWR is its ability to solubilize waxy deposits or paraffins in the oil phase.  In the process, trapped water is absorbed by the SWR/water phase and clean, hydrocarbon-free, inorganic particulate is dropped out.  In a typical waxy deposit of 60% hydrocarbon and 40% water + particulate, the entire 60% hydrocarbon is returned as merchantable product while the remaining 40% is retained as easily disposable waste.  Similar results can be obtained down-hole or in pipelines or surface apparatus.  Once again, SWR contains no aromatic or volatile solvents, and is biodegradable, resulting in zero effluent problems.

A concentration of 60ppm SWR compound based on the water content of the produced fluid is sufficient to achieve or maintain complete paraffin solubilization (somewhat higher concentrations may be needed at lower temperatures more typical of northern operations).  This concentration will inhibit deposition, even from abnormally high-paraffin crudes.  

6.      Tank Bottom Cleaning

SWR has proven very effective at cleaning crude or heavy oil storage tanks containing heavy bottom residues (which are usually a mixture of particulate matter, crude oil and emulsified water or brine).  Similar problems are encountered in field production wash tanks, wastewater ponds and lagoons.  SWR can be used in two ways - (a) to correct problems that have already developed and (b) to prevent those problems from occurring in the first place.

In existing tanks, addition of SWR as a solution at suitable concentrations followed by agitation (using jets of recirculating SWR solution, for example) and subsequent settling quickly liquefies and strips the water from the heavy emulsion (provided that the latter is sufficiently agitated), leaving the hydrocarbon phase (now of somewhat lower viscosity) to float to the top and the residue of sand, dirt, rust and other solids to sink to the bottom.  The result is typically an oil-free tank with an easily removable particulate residue in the bottom, a marketable (or at least recyclable) hydrocarbon product and a water phase which is usually easily disposed of.

If the ingoing oil + water + suspended solid stream is pretreated with about 100ppm of SWR, any oil/water emulsion is broken, oil floats to the top of the tank or pit and is easily separated, heavy particulate settles to the bottom and fine particulate such as flour sand, clay etc. will remain suspended and leave with the water phase containing SWR.  The heavy solids can easily be removed by vacuuming or during scheduled tank cleanings. Occasionally, the effluent water may contain asphaltines.  In some cases, the higher surface energies induced on most materials by the SWR result in flocculation (or at least floc stabilization) of these and other particulates and hence enhanced downstream separation of solids.  This can be especially useful in areas where processed fluids are re-injected since the enhanced separation of suspended solids keeps the injection formation at optimum performance.

7.      Well Stimulation

Use of SWR in old wells experiencing a production decline has been well documented in field trials.  SWR has been shown to work in two ways:

a).  Produced water is blended with SWR at a level of approximately 1000 ppm of SWR and the combined fluid injected into the well with the well off-line.  A pump capable of achieving 800psi is then coupled to the well head and the well pressurized at maximum pressure, thus forcing the fluid into the formation.  The well is left off line for 72 hours, allowing the treated fluid to decontaminate the plugged formation, down-hole pipe, tubing, etc.  Scale removal may be significant factor in the enhanced performance of the cleaned-up well since scaling is often associated with production loss.  Once the well is back on line, recovered solids often consist of carbonaceous substrate, barium mud solids, rust and other likely flow-restriction agents.

b).  Second, and most commonly-used method, which minimizes production losses, is a slug treatment whereby a similar water/SWR formulation is injected down-hole and circulated with the well on line.  Depending on the specific problems that exist for a particular well, frequency of application is dependent of various factors and may vary from daily to weekly or bi-monthly.

8.      Biocide replacement

In some applications, the use of SWR is a proven alternative to the use of dangerous, costly and environmentally unsound biocide products.

The use of biocides in oilfields and in waste water treatment is a common cause of problems in many phases of oil production.  For example, many biocides are highly volatile and exposure to their fumes can involve high personal risk.  In addition, over-treatment is commonplace in the belief that "more is better" (the opposite is true) with the result that the desired results are often not achieved.  A reduction in the volume and frequency of application of most biocides can greatly reduce their undesirable environmental impact.

An example of the use of SWR is the control of hydrogen sulfide production in wash and storage tanks and in waste water treatment ponds and lagoons.  The H₂S is produced by the action of anaerobic bacteria on the organic sulfides present in the tank and pond bottoms where there is no oxygen available (anaerobic bacteria die in the presence of oxygen).  This problem is often addressed by the introduction of toxic and sometimes flammable biocides which do little more than sterilize the entire tank or pond contents, typically with the exception of the inaccessible anaerobic bacteria in the tank bottoms.  However, all aerobic microorganisms present are completely eradicated, and yet it is these that can be used to assist in the biodegradation and eventual disposal of the organic materials in the tank bottoms.  What is really needed is a selective means of eradicating the anaerobic bacteria present while stimulating the aerobic bacteria. 

Addition of biodegradable SWR not only provides nutrient for the anaerobes, thus stimulating their activity and the growth of biomass, but also helps to liquefy and thus provide access to the tank bottoms.  Under these conditions, aerobic destruction of the tank bottom hydrocarbons is accelerated while the oxygen in solution suppresses or even destroys the anaerobic bacteria present which, in turn, halts the production of H₂S.

Addition of conventional biocides will, of course, interrupt this process by eradicating the aerobic bacteria and returning the tank bottom to its original H₂S - producing condition.

The apparent liquefaction (viscosity-reduction) effect of SWR is not fully understood, but is very real.  Since the SWR strips water out of typical oilfield emulsions, it is not due to emulsification (other than transiently, perhaps) but may simply be due to the ability of SWR to destabilize the relatively complex "composite" of water, oil and solids that is representative of most heavy tank residues.  SWR is investigating the effect.

Chlorination of  influent into staged waste water lagoons is also a concern.  Chlorine is typically used to control coliform ( E.coli) bacteria which are present when domestic (human) and oil field waste are commingled.  Chlorine does an excellent job of dealing with the coliform bacteria but also (a) kills off all other forms of bacteria present, some of which are of use in biodegrading any hydrocarbons in the effluent (for example, aromatic solvents such as toluene, benzene and xylene) and (b) it may chlorinate those hydrocarbons into even more dangerous chloro-hydrocarbons such as dichlorobenzene.  The remaining biomass is likely to be inadequate for further biodegradation.  Under these circumstances, oxygen (as measured by BOD) is quickly depleted with the result that the effluent is not bioremediated and H₂S production becomes possible. 

Introduction of SWR into the influent stream well ahead of the chlorine injection point can promote the formation of biomass and hence the biodegradation process in the tank, pond or lagoon.  Although it is not likely that any live E.coli bacteria will remain, chlorination of the effluent water, followed by a brief "hold" can then be used to ensure that all remaining coliform are inactive before the water phase is  transferred to the receiving ecosystem.  Heavy biocide treatment can, as before, actually promote the formation of slime-forming and anaerobic bacteria.

SWR

ADVANTAGES IN THE OILFIELD

• SWR USED DOWN HOLE AS A WELL REJUVENATOR CAN INCREASE THE PRODUCTIVITY AND PROFITABILITY OF DECLINING WELLS WITHIN 72 HRS.
  
  
• SWR RECOVERS MARKETABLE OIL FROM WASH AND STORAGE TANKS, PONDS AND LAGOONS AND OIL PITS
  
  
• SWR IS ENVIRONMENTALLY BENIGN AND BIODEGRADABLE, THUS REDUCING CLEANUP COSTS
  
  
• SWR USED IN PRODUCTION TANKS CAN GREATLY REDUCE OR ELIMINATE THE NEED FOR TOXIC BIOCIDES WHILE PREVENTING H₂S GENERATION AND RESULTING CORROSION
  
  
• SWR ACTS AS A SCALE REMOVER AND RUST INHIBITOR IN PRODUCTION EQUIPMENT AND PIPELINES
  
  
• SWR CAN ENHANCE DOWNSTREAM BODs AND HENCE REMOVE DISCHARGE RESTRICTIONS