Experimental study and mechanism analysis of spontaneous imbibition of surfactants in tight oil sandstone

The process of spontaneous imbibition is the basis of oil recovery from tight oil reservoirs. In this study, spontaneous imbibition experiments were conducted based on tight oil weakly hydrophilic sandstone cores from the Honghe oilfield in the Ordos Basin. Four different types of surfactants, such as nonionic Triton X-100, nonionic Tween-80, cationic dodecyl trimethyl ammonium bromide, and anionic sodium dodecyl benzene sulfonate, were separately dissolved in 30 g/L potassium chloride solution as simulated formation water. The effects of surfactant type on spontaneous imbibition were analyzed, and the results indicated that, because the nonions are adsorbed on the surface via Van der Waals force and adsorb H+ through hydrogen bonds, the two nonionic surfactants altered the wettability of the core from weakly hydrophilic to strongly hydrophilic, the recovery rate was relatively high. The Triton X-100 was selected for subsequent spontaneous imbibition experiments by changing the mass concentration to adjust interfacial tension. It was found that the maximum recovery rate was 32% when the Triton X-100 mass concentration was 0.1%, which indicates that the enhanced recovery rate of spontaneous imbibition requires a sufficiently low wettability factor and a suitably high interfacial tension factor. Finally, the surfactants mixed with 0.03% sodium dodecylbenzene sulfonate and 0.1% Triton X-100 were used for spontaneous imbibition, attaining an oil recovery of up to 45%, which was 21.6% higher than that of single-surfactant imbibition. It was established that the synergistic mechanism depends on the wettability alteration of nonionic surfactant facilitating the spontaneous imbibition, while the anion accelerates oil removal from the core by continuously encasing oil droplets in the aqueous phase. This paper provides a theoretical basis for the imbibition development of weakly hydrophilic tight sandstone with high-salinity formation water.Cited as: Zhang, X., Ye, Q., Deng, J., Zhu, W., Tian, W., Kuang, S. Experimental study and mechanism analysis of spontaneous imbibition of surfactants in tight oil sandstone. Capillarity, 2023, 7(1): 1-12. https://doi.org/10.46690/capi.2023.04.0

Influence of Post-Weld Heat Treatment on Microstructure and Toughness Properties of 13MnNiMoR High Strength Low Alloy Steel Weld Joint

Weld and base metals require hot or cold working during the steel equipment manufacturing process. As a result, the components should be subjected to a normalizing heat treatment in order to recover their mechanical properties. In this study, the submerged-arc welding of the high strength low alloy (HSLA) thick steel plate(13MnNiMoR) is adapted for the vessel head under the normalizing and tempering heat treatment. The findings showed that the material toughness decreases after heating to simulate a vessel head forming process. The stamping process is carried out under the conditions of 980 °C for one hour, normalizing at 920 °C for 1 h and tempering between 600–660 °C for 2 h, respectively. The martensite-austenite (M-A) constituent is distributed in granular bainite and the boundary of austenite in island constituent. Therefore, it was deemed to be the most detrimental to Charpy-V impact toughness. Between normalizing and tempering, intercritical normalizing at 740 °C was added. As a result of the ferrite with fine particles M-A constituent, the toughness increases significantly

A new polyketide, penicillolide from the marine-derived fungus <i>Penicillium sacculum</i>

<p>A new polyketide, penicillolide (<b>1</b>) was isolated from the fermentation broth of the marine-derived fungus <i>Penicillium sacculum</i> GT-308. Compound <b>1</b> is a polyketide with a unique carbon skeleton. The structure of this compound was established via extensive spectroscopic analyses including 1D-, 2D-NMR, and HRESI-MS.</p