The chemistry insight: epoxy sealant as an alternative remedial operation for well integrity

Abstract

Epoxy resin is commonly used in the oil and gas industry due to its excellent toughness, low shrinkage, good adhesive strength, and relatively good thermal resistance. It is used for water shutoff, zonal isolation, cementing, enhanced oil recovery, and preventing leakage in wells. This paper reviews the chemistry aspect of using an epoxy resin system as a sealant to prevent well leakage and it offers insights into the chemistry of the epoxy resin system, as applied in previous studies. The paper also unveils the reasons for the application of this system from the chemistry perspective, allowing this aspect to be better understood. Success in the investigated cases depended on the formulation design. The epoxide and hydroxyl functional groups have been found to contribute substantially to the excellent performance of the sealant system. Furthermore, the amine curing agent triggers the abrupt reaction of the oxirane ring to stabilise when the cured sealant is perfectly applied. Based on the findings, it is suggested that other types of epoxies, namely epoxidised oils, require further study. Finally, in terms of safety and sustainable energy, it is suggested that more curing agent and diluent studies are undertaken.

Biobased Epoxy Resin with Inherently Deep-UV Photodegradability for a Positive Photoresist and Anticounterfeiting

“…Then, DGETA was synthesized by reacting TA with epichlorohydrin according to the traditional method. The chemical structures of TA and DGETA are confirmed by 1 H NMR and 13 C NMR spectra, and the results are shown in Figures 1b,c, S1, and S2. In the 1 H NMR spectrum of TA (Figure 1b), the peaks at 3.84 and 4.26 ppm indicate the formation of a cyclobutane ring, the peaks at 7.23 and 7.35 ppm are attributed to the benzene ring, and the peak at 12.12 ppm belongs to the hydroxyl in the benzene ring.…”

“…Eventually, after removing dichloromethane and then drying in vacuo, a light-yellow solid was collected with a yield of 12.66 g, 62.0%. 1 Preparation of Cured Epoxy Resins. Commercial bisphenol A epoxy resin (DGEBA) and DGETA were cured with a commonly used low-temperature curing agent, 4,4′-diaminodicyclohexylmethane (HDDM).…”

“…Characterizations. 1 H NMR and 13 C NMR spectra were collected on an AVANCE III 400/600 MHz spectrometer (Bruker, Switzerland) with tetramethylsilane (TMS) as an internal standard and CDCl 3 /DMSO-d 6 as a solvent. Differential scanning calorimetry (DSC) measurements were performed under a N 2 atmosphere on a Mettler Toledo Star 1 apparatus and a PerkinElmer DSC8000 apparatus to study the thermal property of the epoxy monomer, curing behavior of epoxy resins, and glass transition temperature (T g ) of cured products.…”

“…An aqueous dispersion (200 mL) of trans-cinnamic acid (5.00 g) was placed in a round-bottom flask and UV irradiated using a high-pressure mercury lamp (400 W, peak at 365 nm) for 48 h. 44 The formed precipitate was filtered, washed with ethyl acetate, and dried in vacuo, and finally, the αtruxillic acid powder was obtained (yield: 3.58 g, 71.6%). 1 Synthesis of Diglycidyl Ether-α-Truxillic Acid (DGETA). α-Truxillic acid (14.8 g, 50 mmol), epichlorohydrin (130 g, 1.5 mol), and a tetrabutylammonium bromide (0.44 g, 3 wt % of α-truxillic acid) catalyst were placed in a three-neck flask equipped with a magnetic stirrer and a reflux condenser, and the mixture was reacted at 75 °C for 3.5 h. After being cooled to 5 °C, 5 g of a 50 wt % sodium hydroxide solution (0.125 mol NaOH) was added dropwise into the flask and reacted for 5 h. The solution was washed with distilled water five times after being diluted with dichloromethane.…”

“…Epoxy resins are one of the classic thermosets and have been widely used in many fields such as adhesives, coatings, and composites owing to their superior mechanical property and solvent and thermal resistance, etc. − As the global consumption of epoxy resins is increasing each year, it leads to a great demand for raw materials. Meanwhile, petroleum-based epoxy resins are facing serious environmental and sustainability problems due to their nonrenewability.…”