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Reservoir sensitivity is a parameter that is used to evaluate the degree of change in reservoir permeability under the influence of external fluids. Accurate evaluation of reservoir sensitivity is conducive to the optimization of fluid parameters during exploration and development. Taking the Wenchang Formation and Enping Formation of the Paleogene in the Huilu area of the Pearl River Mouth Basin as the research object, reservoir sensitivity experiments were carried out. Combined with the corresponding experimental results obtained using methods such as thin section identification, scanning electron microscopy (SEM), X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), and screening analysis, based on mineral sensitization and pore structure sensitization, qualitative and quantitative evaluations of reservoir sensitivity were carried out, and factors affecting sensitivity and sensitization mechanisms were analyzed. This work shows the following: (1) The sandstone reservoirs in the two areas have the same clay type, but the total clay content of the Wenchang Formation is greater than that of the Enping Formation. The porosity of the Wenchang Formation is less developed than the Enping Formation. (2) The Wenchang Formation has weak or moderately weak water sensitivity and moderately weak or moderately strong flow velocity sensitivity. The water sensitivity of the Enping Group samples is moderately weak or moderately strong, the flow rate sensitivity is moderately weak, the alkali sensitivity is weak, the acid sensitivity is moderately weak, and the salinity sensitivity is moderately weak or moderately strong. (3) The sensitivity of the Wenchang Formation is mainly affected by the content of clay minerals. The sensitivity of the Enping Formation is also affected by the clay content and type. Although the clay content is not high, the permeability is more susceptible to sensitivity due to the pore structure and debris particle distribution characteristics. These conclusions are beneficial for the selection of fluid parameters and efficient reservoir development. [ABSTRACT FROM AUTHOR]

ABSTRACT: Cellulose nanocrystals (CNCs) as attractive nanomaterials are widely distributed in higher plants, algae, and marine animals. Herein, three kinds of CNCs were isolated by sulfuric acid hydrolysis from cotton pulp, algae, and tunicate cotton, respectively. Their morphologies and size were characterized by scanning electron microscope and atomic force microscope. The results showed that the aspect ratio of CNCs was in the order of CNCs from cotton pulp (CCNCs) (15 ± 10) < CNCs (ACNCs) from algae (ACNCs) (18 ± 12) < CNCs from tunicate (TCNCs) (75 ± 60). The phase transitions of CNC suspensions were also determined by phase diagram and rheological experiments. Two critical concentrations from isotropic to biphasic phase (Ci) and from biphasic to anisotropic phase (Ca) were measured and calculated, indicating that CNCs with higher aspect ratio reached Ci and Ca at lower concentration. Furthermore, the critical concentrations were also checked by polarized optical microscopy measurement. This work provided important information for construction of CNCs reinforced nanocomposites and investigation of CNCs chiral nematic liquid crystals. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45702. [ABSTRACT FROM AUTHOR]