Adsorption behavior of welan gum on quartz sand in reservoir

Welan gum (WLG) has been reported being used in chemical flooding and hydraulic fracturing for hightemperature and high-salinity reservoir development due to its good temperature resistance and salt tolerance properties. The adsorption and retention of WLG in reservoir rocks will reduce the reservoir permeability and affect the economic development of oil and gas fields. However, there are no reports about the adsorption of WLG on quartz sand. Therefore, in this study, standard curve of absorbance-WLG concentration was established by anthrone colorimetry method. The adsorption behavior accorded with the Langmuir adsorption isotherm. The adsorption capacity was 4.01 mg/g. By means of Fourier transform infrared spectrum analysis, X-ray diffraction technology, thermogravimetric analysis, scanning electron microscope, optical microscope, and contact angle measurement, it is confirmed that the adsorption was physical adsorption and surface adsorption, and did not have obvious influence on crystal spacing and wettability of quartz sand. Based on this, the study of the influence of reservoir conditions showed that: the adsorption capacity decreased with the increase of temperature; pH value had little effect; the adsorption capacity first increased and then decreased with the increase of inorganic salt content, and this trend varied with the types of inorganic salts.