American Oil and Gas Reporter - October 2019 - 80

SpecialReport: Oil Field Chemistry
Enzymes
Some of the ingredients entering the
oil field are enzymes, which are proteins
produced by living cells that catalyze
specific chemical reactions, increasing
reaction frequency up to millions of times
the norm. In humans, enzymes aid digestion, metabolize and eliminate waste
from our bodies, and play a crucial role
in muscle contraction. For millennia, they
have been an essential part of cheese
making, brewing and baking.
Improved methods for producing enzymes and the ability to dramatically
change their properties through genetic
engineering have opened the door to new
applications in a wide range of industries.
They have tremendous potential to reduce
costs, produce less waste, and help decrease the need for energy, water and
toxic chemicals.
Enzymes are studied for use in industrial-scale catalysis because they offer
several advantages over traditional catalysts, from their ability to function in
milder reaction conditions, e.g. to facilitate
reactions at low temperatures, to their
exceptional product selectivity and lower
environmental and physiological toxicity.
There are more than 3,000 known enzymes, but only 150-170 are in use commercially.
Enzymes are used in the food, agricultural, cosmetic and pharmaceutical industries in order to increase the reaction
rates, yield and purity of the finished
products. Breweries could not make beer
without enzymes and the yeasts that produce them.
Industrial uses for enzymes are increasing with applications in the production
of biofuels and biopolymers. Enzymes
are transforming the nonfood industrial
sectors to improve process efficiencies
and decrease energy usage. For example,
acrylamide, a building block for manufacturing a wide range of polymers and
copolymers, including water treatment
polymers, friction reducers and scale inhibitors, is made from acrylonitrile using
nitrile hydratase. This enzyme efficiently
converts acrylonitrile into acrylamide
under mild conditions and offers significant
improvements in yield efficiency and reduced energy needs compared with traditional chemical techniques.
80 THE AMERICAN OIL & GAS REPORTER

Enzymes are also improving the production process for hydrogen peroxide, a
simple molecule used as an oxidizer,
bleaching agent and antiseptic. For more
than 75 years, hydrogen peroxide has
been synthesized through a single, complex
chemical process that involves a succession
of hydrogenation and oxidation reactions
from a palladium catalyst. Certain enzymes
have long been known to work with hydrogen peroxide in various biological
systems.
Translating that knowledge into a biological-based method to create hydrogen
peroxide proved difficult-until recently.
A specialty chemicals manufacturer has
developed and deployed the world's
first and only bio-based chemical peroxide. Solugen's proprietary enzymes
produce bio-based peroxides that are in
use to treat, clean and oxidize several
industries' waste waters, including oil
field produced water.
Enzyme-Based Breakers
Efficiently recovering hydraulic fracturing fluid normally means reducing the
fluid's viscosity after the frac using a
breaker chemical. The breaker's main
purpose is to reduce the molecular weight
of the completion fluid's viscosifying
agent, thereby minimizing viscosity and
maximizing both the volume and rate of
fluids returning from the formation. Misapplication or use of an ineffective breaker
can cause significant damage in the proppant pack and reduced permeability.
Common frac fluid breakers include
chemical oxidizers such as hydrogen peroxide and persulfates or organic acids.
However, enzyme-based breakers such as
hemicellulase, cellulose, amylase and
pectinase have been widely used in water-based fracturing fluids for three decades.
Enzyme breakers have several advantages over traditional oxidizer chemicals.
First, enzymes specifically break longchain polymers without causing undesirable damage to the wellbore, formation
or fracturing equipment. Second, because
the enzymes are catalysts, they are not
consumed in the breaking process and
work well even in low concentrations.
Third, enzymes are nontoxic compared
with oxidant breakers.
As an example, the enzyme mannanase

effectively can break linear and borate
crosslinked guar under broad ranges of
temperature and pH. This breaker belongs
to the glucanase family and reduces gel
viscosity by specifically targeting ß-1,4
glycosidic bonds between the mannose
units in guar.
Enzyme-based breakers can work
well in situations where chemical oxidizers struggle. For example, chemical
oxidizers have trouble breaking or degrading the polyacrylamide-based friction
reducers frequently used in slickwater
completions. Asparaginase, an enzyme
derived from a fungus used in East Asia
for soybean fermentation, has proven to
be far more effective.
Bio-Polymers
Bio-based polymers are materials produced from renewable resources. The
terms bio-based polymers and biodegradable polymers are used extensively in literature, but there is a key difference between them. Biodegradable polymers are
materials whose physical and chemical
properties deteriorate and eventually degrade completely when exposed to microorganisms, aerobic and anerobic
processes or hydrolysis. Bio-based polymers can be degradable (e.g. polylactic
acid) or nondegradable (e.g. biopolythioesters). Similarly, while many biobased polymers are biodegradable (e.g.
starch and polyhydroxyalkanoates), not
all biodegradable polymers are bio-based
(e.g. polycaprolactone).
Bio-based polymers are attracting increased attention motivated by environmental concerns and the realization that
global petroleum resources are finite and
more renewable, sustainable materials
must be identified. Bio-based polymers
not only replace existing polymers in
several applications, but also provide new
combinations of properties that unlock
new applications.
Bio-based polymers typically are produced through three methods: 1) extraction
and separation from agricultural resources,
2) fermentation processes and 3) conventional synthesis using building blocks
from renewable resources, including lignocellulosic biomass, fatty acids and organic waste. Some bio-based polymers,
such as proteins, nucleic acids and poly-

American Oil and Gas Reporter - October 2019

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