Hydraulic fracturing has been used by the oil and gas industry as a way to boost hydrocarbon production since 1947. Recent advances in fracturing technologies, such as multistage fracturing in horizontal wells, are responsible for the latest hydrocarbon produc- tion boom in the US. Linear or crosslinked guars are the most commonly used fluids in traditional fracturing operations. The main functions of these fluids are to open/propagate the fractures and transport proppants into the fractures. Proppants are usually applied to form a thin layer between fracture faces to prop the fractures open at the end of the fracturing process. Chemical breakers are used to break the polymers at the end of the fracturing process so as to provide highly conductive fractures. Concerns over fracture conduc- tivity damage by viscous fluids in ultra-tight formations found in unconventional reservoirs prompted the industry to develop an alter- native fracturing fluid called "slickwater". It consists mainly of water with a very low concentration of linear polymer. The low concentration polymer serves primarily to reduce the friction loss along the flow lines. Proppant-carrying capability of this type of fluids is still a subject of debate among industry experts. Constraints on local water availability and the potential for damage to formations have led the industry to develop other types of fracturing fluids such as viscoelastic surfactants and energized fluids. This article reviews both the traditional viscous fluids used in conventional hydraulic fracturing operations as well as the new family of fluids being devel- oped for both traditional and unconventional reservoirs. V C 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131 ,4 0735.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/app.40735

A review of fracturing fluid systems used for hydraulic fracturing of oil and gas wells

A review of the current progress of CO2 injection EOR and carbon storage in shale oil reservoirs

http://nlhfrp.ca/wp-content/uploads/2015/01/1-s2.0-S0304389414003021-main.pdf

Physical, chemical, and biological characteristics of compounds used in hydraulic fracturing

Application of nanotechnology by means of nanoparticles and nanodispersions in oil recovery - A comprehensive review

The technology of hydraulic fracturing for hydrocarbon well stimulation is not new, but only fairly recently has become a very common and widespread technique, especially in North America, due to technological advances that have allowed extracting natural gas from so-called unconventional reservoirs (tight sands, coal beds and shale formations). The conjunction of techniques such as directional drilling, high volume fracturing, micro-seismic monitoring, etc. with the development of multi-well pads has been especially successful in the last years in their application to shales, making gas production from shales technically and economically feasible. In Europe, the potential application of this technology has led to both great worries and high expectations: worries regarding the alleged magnitude of the environmental impact, and expectations about production of indigenous hydrocarbons. Other types of formation stimulation exist that do not make use of water-based fluids (for instance, explosive fracturing, dynamic loading, etc.), or that make use of fluids other than water. These are currently not extensively applied due to performance considerations. As for any other industrial activity, the deployment of high-volume hydraulic fracturing could potentially entail some risks to the environment. Among the concerns raised are high usage of water, methane infiltration in aquifers, aquifer contamination, extended surface footprint, induced local seismicity, etc. New technologies could help addressing these concerns (for instance by using non-toxic chemicals, by reducing or eliminating altogether the usage of water, by considerably reducing the surface footprint of a well, etc.). This report reviews hydraulic fracturing and alternative fracturing technologies, by searching the open literature, patent databases and commercial websites (mainly in the English language). For each identified technique, an overview is given. The technique is then briefly explained, and its rationale (reasons for use) is identified. Potential advantages and disadvantages are identified, and some considerations on costs are given. Finally, the status of the technique (for instance, commercially applied, being developed, concept, etc.) is given for its application to shale gas production. As the Commission’s in-house science service, the Joint Research Centre’s mission is to provide EU policies with independent, evidence-based scientific and technical support throughout the whole policy cycle. Working in close cooperation with policy Directorates-General, the JRC addresses key societal challenges while stimulating innovation through developing new standards, methods and tools, and sharing and transferring its know-how to the Member States and international community. Key policy areas include: environment and climate change; energy and transport; agriculture and food security; health and consumer protection; information society and digital agenda; safety and security including nuclear; all supported through a cross- cutting and multi-disciplinary approach. L D -N A -2 6 3 4 7 -E N -N

/pdf/an-overview-of-hydraulic-fracturing-and-other-formation-b2rkdo3z29.pdf

An overview of hydraulic fracturing and other formation stimulation technologies for shale gas production

Role of molecular diffusion in heterogeneous, naturally fractured shale reservoirs during CO2 huff-n-puff

Water-based polymer gels are used widely in the oil and gas industry to viscosify fluids used in the hydraulic fracturing of production wells, where they serve to increase the force applied to the rock and to improve the transport of proppants used to maintain the fracture after formation. After fracturing, the gel must be degraded to a low viscosity with enzymes or gel breakers. Existing systems add the breaker either directly to the gelant or encapsulated in beads that are crushed when the applied pressure is released and the fractures close. In the former case, the gel may be broken prematurely, and this may prevent efficient fracture propagation and proppant trans- port, whereas in the latter case, the breaker may not be uniformly distributed throughout the gel, with the result that the gel is incompletely broken and the hydraulic con- ductivity of the well is reduced. To obtain delayed release, combined with the homogeneous distribution of enzyme throughout the gel, polyethylenimine-dextran sulfate poly- electrolyte complexes were used to entrap pectinase. Such particles were originally developed to entrap pharmaceuti- cals, and we previously demonstrated their ability to delay the release of gel crosslinking agents for oilfield applica- tions. The degradation of both the viscosity and visco- elastic moduli of borate-crosslinked guar gel by pectinase loaded in polyelectrolyte nanoparticles was delayed by up to 12 h, compared to about 2 h for equivalent systems where the pectinase was not entrapped. The combination of homogeneous mixing and the delayed release of enzymes packaged in polyelectrolyte complex nanopar- ticles showed promise for improved cleanup after hydra- ulic fracturing. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 1292-1298, 2011

/pdf/fracturing-fluid-cleanup-by-controlled-release-of-enzymes-23k2yix4cn.pdf

Reza Barati

Papers

A review of fracturing fluid systems used for hydraulic fracturing of oil and gas wells

A review of the current progress of CO2 injection EOR and carbon storage in shale oil reservoirs

Role of molecular diffusion in heterogeneous, naturally fractured shale reservoirs during CO2 huff-n-puff

Fracturing fluid cleanup by controlled release of enzymes from polyelectrolyte complex nanoparticles

A workflow to estimate shale gas permeability variations during the production process