Yaqi Ge,Pengfei Diao,Xiangxu Li,Yukun Zhou,Zhenchun Xu,Huiguang Bian,Yao Xiao,Chuansheng Wang
In this paper, pyrolysis carbon black (CBp) was introduced into nitrile butadiene rubber (NBR), the effects of the ratio of CBp and carbon black (N326) on the properties of NBR composites were investigated, and the optimal ratio was determined. On this basis, the accelerator DPG, coupling agent KH550 and CBp were modified by ball milling and plasma. The results showed that when the ratio of CBp to N326 was 40:15, the overall properties of NBR composites was better. Compared with the unmodified CBp/NBR composites, the change rate of tensile product, resilience and DIN abrasion of ball milling-plasma modified CBp/NBR composites in oil environment were reduced by 52.96%, 12.81%, and 27.19%, respectively, and the tear strength after double damage by high temperature and oil bath was increased by 15.63%, which resulted in better oil and high temperature-resistance. In summary, the ball milling-plasma combined with DPG/KH550 modified CBp can not only replace N326 carbon black, but also realize the preparation of NBR composites with better oil and high temperature-resistance.
In foam flooding, foams stabilized by conventional surfactants are usually unstable in contacting with crude oil, which behaves as a strong defoaming agent. In this article, synergistic effects between different surfactants were utilized to improve foam stability against crude oil. Targeted to reservoir conditions of Daqing crude oil field, China (45 °C, salinity of 6778 mg L −1 , pH = 8–9), foams stabilized by typical anionic surfactants fatty alcohol polyoxyethylene ether sulfate (AES) and sodium dodecyl sulfate (SDS) show low composite foam index (200–500 L s) and low oil tolerance index (0.1–0.2). However, the foam stability can be significantly improved by mixing the anionic surfactant with a sulfobetaine surfactant, which behaves as a foam stabilizer increasing the half-life of foams, and those with longer alkyl chain behave better. As an example, by mixing AES and SDS with hexadecyl dimethyl hydroxypropyl sulfobetaine (C 16 HSB) at a molar fraction of 0.2 (referring to total surfactant, not including water), the maximum composite foaming index and oil tolerance index can be increased to 3000/5000 L s and 1.0/4.0, respectively, at a total concentration between 3 and 5 mM. The attractive interaction between the different surfactants in a mixed monolayer as reflected by the negative β s parameter is responsible for the enhancement of the foam stabilization, which resulted in lower interfacial tensions and therefore negative enter (E), spreading (S), and bridging (B) coefficients of the oil. The oil is then emulsified as tiny droplets dispersed in lamellae, giving very stable pseudoemulsion films inhibiting rupture of the bubble films. This made it possible to utilize typical conventional anionic surfactants as foaming agents in foam flooding.
Sanbao Dong,Jiabao Fan,Chenwei Liu,Yongli Yan,Weiwei Han
Liquid buildup in gas wells would undoubtedly obstruct the gas production. The use of foaming surfactants to generate foams and remove the loaded liquid is very common. Due to the undesirable conditions (e.g., high condensate cut (ratio of condensate oil volume to total liquid volume) and high salinity, etc.) that often encountered in the wells, different foaming surfactants were often compounded together to unload liquid in gas wells. In this paper, lauramide propyl dimethylamine (C12 Amine), palmitamide propyl dimethylamine (C16 Amine) and cocamidopropyl betaine (CAPB) were synthesized and compounded with L-aspartic acid (Asp) and N-lauroylsarcosine sodium (LSS) to form foaming supramolecular complexes through optimization (with Waring blender method and liquid unloading tests) to quantify their application potentials in foam-based deliquification treatment for gas wells. The C12 Amine-Asp-LSS-CAPB complex (in an optimized mole ratio of 10:4:14:7) exhibited superior condensate tolerance than the C16 Amine-Asp-LSS-CAPB complex (in an optimized mole ratio of 10:4:14:42). The salinity posed a significant influence on the liquid unloading performance ( k ) and foaming efficiency ( ƞ , defined as the ratio of the foam mass to the initial liquid mass) of the C12 Amine-Asp-LSS-CAPB complex, however, the nitrilotriacetic acid trisodium (NTA) can greatly enhance the properties of the C12 Amine-Asp-LSS-CAPB complex against the salinity (up to 6 × 10 4 mg/L). The temperature (25 °C −90 °C) favored the performances (as indicated by k and ƞ ) of the C12 Amine-Asp-LSS-CAPB complex, which achieved k and ƞ values of 85.0% and 100% at 90 °C, respectively. Meanwhile, the synergy observed in the foaming ability, foam stability and liquid unloading performance tests using the C12 Amine-Asp-LSS-CAPB mixture was also proved by the surface tension analysis and the calculations of the supramolecular interactions (interaction energies and electrostatic interactions).
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