In order to realize the safe transportation of liquefied ethane pipeline in the Oilfield of China, it is necessary to fully study the process of pipeline replacement, operation and shutdown. The accurate calculation of physical property parameters and critical parameters is the basis of studying the gas-liquid two-phase flow and heat and mass transfer process of liquefied ethane in the pipeline. In this paper, different equations of states (EOSs) were used to predict the physical properties (such as density, dew point and dynamic viscosity) of ethane or ethane mixture, and the predicted results were compared with the corresponding experimental data from the literature. The prediction performance of different EOSs were evaluated by using two evaluation indicators, including average absolute deviation (AAD) and average relative deviation (ARD). The results showed that the PR-Peneloux EOS has the best performance for predicting the density of CH₄-C₂H₆-N₂ mixture with an ARD value of 4.46%; for predicting the dew point, the BWRS EOS exhibits the superior performance with an ARD value of 0.58%; and for predicting dynamic viscosity, the SuperTRAPP formula has the smallest calculation error, with an ARD value of 1.33%. Considering the comparison results of the calculation accuracy of density, dew point and dynamic viscosity of ethane or ethane mixture by using different EOSs, PR-Peneloux EOS was recommended to calculate the phase characteristics in the process of ethane pipeline replacement operation. The phase characteristics of ethane for pipeline transport in the oilfield of China were obtained. The critical temperature is 32.79℃ and the critical pressure is 4.97 MPa.

In order to effectively adjust reservoir heterogeneity and further exploit the remaining oil, a new type of low-viscosity gel was prepared by adding a regulating agent, retarder, and reinforcing agent on the basis of a polymer + Cr³⁺ crosslinking system. The new gel has the advantages of low initial viscosity, a slow gel formation rate, and high strength after gel formation. The effectiveness of the gel was verified through three-layer core displacement experiments, and the injection scheme was optimized by changing the slug combination of the polymer and the gel. The results showed that the gel can effectively block the high-permeability layer and adjust reservoir heterogeneity. An injection of 0.1 pore volume (PV) low-initial-viscosity gel can improve oil recovery by 5.10%. By changing the slug combination of the gel and polymer, oil recovery was further increased by 3.12% when using an injection of 0.07 PV low-initial-viscosity gel +0.2 PV high-concentration polymer +0.05 PV low-initial-viscosity gel +0.5 PV high-concentration polymer.

High-gravity rotating packed beds enhance mass transfer via high-gravity fields, where the flow and viscosity distribution of polymer solutions govern dissolution efficiency and equipment compactness. Understanding these behaviors is essential for optimizing polymer dissolution in offshore polymer flooding, yet experimental methods are hindered by poor light transmittance and observational blind spots, making it difficult to capture the dynamic dispersion and evolution of polymer solutions within the wire mesh packing. To address this issue, a two-dimensional computational model was constructed by combining the VOF multiphase model with the Carreau–Yassuda viscosity model, accounting for the shear-thinning characteristics and viscosity variations of the polymer solution. The effects of zero-shear viscosity, rotational speed, and inlet velocity on flow morphology, aggregation, and apparent viscosity distribution were systematically examined. Results show the following: (1) Increasing rotational speed from 300 to 900 rpm promotes the transition from film-dominated to droplet-dominated flow, increasing zero-shear viscosity from 59 to 348 mPa·s suppresses dispersion and forms coexisting films and droplets, and increasing inlet velocity from 1.74 to 3.17 m/s drives the transition from droplet-dominated to film-dominated flow. (2) Increasing rotational speed reduces apparent viscosity by up to 30% and improves distribution uniformity, with a turning point near 1000 rpm; inlet velocity has limited effects, with radial distribution higher in the inner region. (3) The Carreau–Yassuda model reveals a shear-thinning effect, where high rotational speed mitigates the influence of high zero-shear viscosity, and the combination of high rotational speed and high inlet velocity synergistically enhances dispersion. These findings provide a theoretical basis for optimizing polymer dissolution in high-gravity carbon capture processes.