Performance Evaluation of Enzyme Breaker for Fracturing Applications under Simulated Reservoir Conditions

Abstract

Fracturing fluids are being increasingly used for viscosity development and proppant transport during hydraulic fracturing operations. Furthermore, the breaker is an important additive in fracturing fluid to extensively degrade the polymer mass after fracturing operations, thereby maximizing fracture conductivity and minimizing residual damaging materials. In this study, the efficacy of different enzyme breakers was examined in alkaline and medium-temperature reservoirs. The parameters considered were the effect of the breaker on shear resistance performance and sand-suspending performance of the fracturing fluid, its damage to the reservoir after gel breaking, and its gel-breaking efficiency. The experimental results verified that mannanase II is an enzyme breaker with excellent gel-breaking performance at medium temperatures and alkaline conditions. In addition, mannanase II did not adversely affect the shear resistance performance and sand-suspending performance of the fracturing fluid during hydraulic fracturing. For the same gel-breaking result, the concentration of mannanase II used was only one fifth of other enzyme breakers (e.g., mannanase I, galactosidase, and amylase). Moreover, the amount of residue and the particle size of the residues generated were also significantly lower than those of the ammonium persulfate breaker. Finally, we also examined the viscosity-reducing capability of mannanase II under a wide range of temperatures (104–158 °F) and pH values (7–8.5) to recommend its best-use concentrations under different fracturing conditions. The mannanase has potential for applications in low-permeability oilfield development and to maximize long-term productivity from unconventional oilwells.

A Review of Advanced Molecular Engineering Approaches to Enhance the Thermostability of Enzyme Breakers: From Prospective of Upstream Oil and Gas Industry

“…The mannanase enzyme is widely used at the industrial level such as in feed, medicines, and in the upstream oil industry as a gel breaker. Mannanase breaks the β-1,4-glycosidic bonds in guar gum with fewer residues [11]. As compared to others gel breakers, the mannanase enzyme was first isolated from hot spring bacteria to work in extreme oil wells at high temperatures.…”

“…Enzyme breakers have several advantages compared to traditional chemical oxidizers such as being environmentally friendly, their ability to break long-chain polymers without altering near-wellbore petrophysical impairment, and their effectiveness-a minimal number of enzymes can do a lot of work because of their catalytic nature, etc. [11]. Conventionally, the enzyme breakers α-1,6-galactosidase and β-1,4-mannanase were isolated from the hyperthermophilic bacterium Thermotoga neapolitana to degrade guar gum.…”

“…(5) Enzymes are substrate specific that increase their specificity to the target molecule. (6) Enzymes do not affect the tubes or equipment during hydraulic fracturing [11]. Enzyme breakers have been commonly used in a water-based fracturing fluid for many decades.…”

Strategies for Preparation of Chiral Stationary Phases: Progress on Coating and Immobilization Methods

“…The separation of enantiomers in an analytical and preparative scale is undoubtedly a matter of crucial importance in diverse research areas [ 1 ]. Liquid chromatography (LC) using chiral stationary phases (CSPs) proved to be the most versatile and useful approach for the evaluation of enantiomeric purity in quality control [ 2 , 3 ], the preparative enantioresolution process [ 4 , 5 ], monitoring enantiomeric reactions [ 6 , 7 ], food analysis [ 8 , 9 ], the stereochemistry determination of natural compounds [ 10 , 11 ], pharmacokinetic [ 12 ] and environmental studies [ 13 , 14 ], among other applications. Over the years, several types of CSPs have been developed which comprise polysaccharide derivatives, Pirkle-type, cyclodextrins, crown-ether, proteins, macrocyclic antibiotics, ion-exchange, cyclofructans, synthetic polymers and molecularly imprinted CSPs [ 15 , 16 , 17 ].…”

Delayed Breaker Systems To Remove Residual Polymer Damage in Hydraulically Fractured Reservoirs

“…Because of the great importance of enzyme activity in attacking the polymer chains, several studies have been conducted on various enzyme breakers that can degrade the glycosidic bonds of guar-based polymers, such as amylose, cellulose, galactose, pectinose, and mannanose. ,, There are various types of mannanase enzymes, which act on mannanose polymers (the backbone of guar polymer), but only a certain type exhibits higher activity at high temperatures and a wide pH range. , From the comparative studies conducted by Meng et al using mannanase, amylase, cellulase, pectinase, and xylanase, it was reported that only mannanase provides a rapid and homogeneous guar-polymer breakage at low concentrations retaining its activity over a wide range of temperatures and pH ranges. However, it was also found that the activity of wild mannanase strain is limited to 150–160 °F.…”