Oil and gas fields encounter issues associated with clay minerals through drilling and production. Depending on the types of clay minerals, they pose the danger of swelling and migration upon exposure to incompatible water. Drilling introduces water through drilling mud, and production introduces water through different treatments such as acid stimulation and hydraulic fracturing.The recovery of oil and gas from subterranean formations has been troublesome in formations that contain water-sensitive minerals, e.g., water-swellable clays, such as clays in the smectite group, and fines capable of migrating when disturbed, such as silica, iron minerals, and alkaline earth metal carbonates.It has been common practice to add salts to the treatment fluids. The salts adsorb to the clay surfaces in an ion exchange process that can temporarily reduce the swelling and/or migration of the clays. Another method used is to coat the area with a polymer in order to physically block the surface of the clays. This paper will mention the types of clays related to the oil industry, describe the structure of clays, mention the mechanisms behind swelling and migrating, and compare the different developments in the field of clay inhibition.

Borate crosslinkers are the most commonly used crosslinker in fracturing fluids. However, they exhibit lower performance at high temperature, high pressure, high water salinity, and low pH applications. Consequently, zirconium crosslinkers are utilized to address these limitations. Zirconium crosslinking chemistry is complex and depends on many factors such as pH, metal to ligand ratio, ligand order, ionic strength, and type of polymer used, which in turn influence the delay time, thermal stability and shear resistance performance. This work evaluates the rheological performance of four different zirconium crosslinkers with a biopolymer and a synthetic polymer. The tested crosslinkers are manufactured in different chemical structures. The two polymers tested are 40 lb/1,000 gal CMHPG and 40 lb/1,000 gal synthetic polymer. The rheological performance was measured through HPHT rheometer (100 s−1 shear rate) at 200-400°F for 2 hours. The shear tolerance performance was also evaluated under a custom shear rate schedule (100-1000 s−1). The results show significant variation in crosslinking performance due to the changes in crosslinker chemical structure and type of polymer used. Zirconium lactate and propylene glycol crosslinker shows the highest enhancement in shear and thermal stability with CMHPG based fracturing fluids. Surprisingly, the same crosslinker performed the least with synthetic polymer-based fracturing fluids. However, Zirconium triethanol amine and lactate showed significant enhancements in shear and thermal stability with synthetic polymer-based systems. The results also show and discuss the influence of systematically changing crosslinker ligand order in CMHPG and synthetic polymer-based fracturing fluids. The work studies the influence of the zirconium crosslinker chemical structure on the rheological properties of both biopolymer and synthetic polymer-based fracturing fluids. The performance evaluation shows that delay time, shear and thermal stability can be enhanced by manufacturing the appropriate crosslinker chemical structure, thus reducing additional additives required used and saving cost.

Hydraulic fracturing technology has grown popular with the rapidly increasing development of tight conventional and unconventional reservoirs. A major concern with this technique is the use of large amounts of water in these treatments. The use of water causes many potential damaging issues in the formation and limits the amount that can be saved for future generations. One solution is waterless fracturing treatments, which were developed to reduce or eliminate the need for water in hydraulic fracturing. Hydraulic fracturing treatments consume at least 200,000 gallons of water in conventional wells and up to 16,000,000 gallons of water in unconventional wells. The pumped water must include clay stabilizers to deal with the sensitive clays in the formation. Additionally, using water poses a risk of inorganic scale precipitation near the wellbore. Water can also cause severe emulsions that can lead to emulsion blockage cases. Moreover, there are significant reports of water blockage cases in tight gas wells. Only a mere 10-30% of pumped water flows back after the treatment, with the rest attached to clays, or stuck in the pores due to high capillary pressures. Water-based fluids can also cause alterations to relative permeability, and liquid holdup cases in many gas wells. These issues can certainly increase near wellbore skin and reduce production rates. At the end of the treatment, water still causes issues related to disposal and separation prior to diverting it to the plant. The main challenges in developing waterless fluids include feasibility, environmental friendliness, and effectiveness to stimulate the reservoir. This review will cover the various waterless fracturing methods such as hydrocarbon-based, liquid CO2, energized, and foamed fluids (CO2 and N2 foams) as well as their advantages and disadvantages. Studies into the properties of these fluids, such as rheology, solubility, compatibility, will also be discussed. Field trials will be examined where applicable. This literature review examines various waterless alternatives to traditional fluids for hydraulic fracturing. From this paper, readers can better understand the nature of waterless technologies and be able to better evaluate these technologies for fracturing purposes.

The action of anodic glow discharge electrolysis (gde) on ethanol in neutral aqueous phosphate buffer gave acetaldehyde, butan-2,3-diol, hydrogen peroxide, and acid. The yields of these products were found to vary substantially with the presence or absence of oxygen and in particular with oxygen flow rate and substrate concentration. A mechanism has been proposed for the reaction of substrate in both the presence and absence of oxygen.Ethanol vapor and water vapor, over aqueous ethanol solutions, were subjected to glow discharge electrolysis (gde).by Klemenc (1), who examined the gaseous products only. Gde has been performed also on pure methanol (2), with a variety of supporting electrolytes; products were a complex mixture of simple breakdown species. Scholes and co-workers (3) studied the effects of x-rays (200 kV) on ethanol in aqueous solution and found that in the presence of oxygen the products were hydrogen peroxide and acetaldehyde alone. Using deaerated solutions they found acetaldehyde and butan-2, 3-diol, with traces of hydrogen peroxide (under acid conditions). Seddon and Allen (4) studied the hydrogen yields arising from the 7-radiolysis of neutral aqueous solutions of ethanol both in the presence and in the absence of oxygen. Recently Schultze and Schulte-Frohlinde (5) studied the effects of the v-irradiation of dilute aqueous ethanol under a gaseous mixture of oxygen and nitrous oxide. The products were acetaldehyde, acetic acid, glycolaldehyde, ethylene glycol, and hydrogen peroxide.A careful study was made of the total yields in the present work to determine the ultimate fates of all the radicals generated by gde: As will be seen, we have accounted for G(OH) in terms of our products. We also studied carefully the proportion cf acetaldehyde and hydrogen peroxide since this gives valuable evidence about the reaction possibilities, and we were able to show that in gde under oxygen flow rates high enough to scavenge all the 1-hydroxyethyl radicals (CHsCHOH) and at ethanol concentrations high enough to scavenge all the hydroxyl radicals, there is a particularly straightforward interaction between the 1-hydroxyethylperoxyl radicals (CH3 CI-IOH) 02 yielding acetaldehyde and hydrogen peroxide in 2:1 proportions. ExperimentalThe ethanol solutions were prepared by dissolving the correct amounts of pure absolute ethanol in neutral phosphate buffer solution, except for runs on acid determination under oxygen where very dilute alkali was used. The solutions after gde were analyzed for hydrogen peroxide (6), acetaldehyde (7), butan-2, 3-diol, and acid. since these compounds were the products of x-irradiation of phosphate buffer/ ethanol solutions (3). Other species sought by the wor]~ers who used x-irradiation were acetic acid, ethylene glycol, glycolaldehyde, ethyl hydroperoxide, diethyl peroxide, peracetic acid, and ethyl acetate, but no evidence was found for any of these. The acetaldehyde determination is essentiM]y co]orimetric: the absorbance, which declined rapidly, was recorded as Key words: glow disc...

Commonly used borate crosslinkers produce weak fracturing fluids at high temperature, high pressure, high salinity, and low pH conditions. Accordingly, zirconium crosslinkers were developed to address these shortcomings. Zirconium crosslinking chemistry is complicated and depends on many factors such as pH, ionic strength, ligand type, ligand order, and ligand to metal ratio. This work evaluated the rheological performance of four commercial zirconium crosslinkers with a polysaccharide and a polyacrylamide. The tested crosslinkers are manufactured with similar zirconium content but differ in ligand type and ligand order, producing different crosslinker chemical structures. The rheological performance was assessed using an HPHT rheometer at 93–204°C for 1.5 h. Shear tolerance performance was evaluated under shear rates of 40 s−1–1000 s−1. The results showed substantial variation in crosslinking performance due to the differences in the crosslinker chemical structure and type of polymer used. Zirconium lactate and propylene glycol crosslinker exhibited the greatest enhancement in shear and thermal stability with the polysaccharide‐based fracturing fluid. Remarkably, the same crosslinker performed the least with the polyacrylamide‐based fracturing fluid. However, Zirconium triethanolamine and lactate demonstrated considerable improvements in shear and thermal stability with the polyacrylamide‐based system. The work unravelled the influence of the zirconium crosslinker ligand type and ligand order on the rheological properties of both tested polymers. The performance evaluation showed that shear resistance, crosslinking delay, and thermal stability could be improved by utilizing the appropriate crosslinkers. The enhancements ultimately reduce additional additives required, prevent screenouts, and save cost during field treatments.