Experimental study of gas-water elongated bubble flow during production logging

In order to improve the interpretation of production log data on gas-water elongated bubble （EB） flow in horizontal wells, a multi-phase flow simulation device was set up to conduct a series of measurement experiments using air and tap water as test media, which were measured using a real production logging tool （PLT） string at different deviations and in different mixed flow states. By understanding the characteristics and mechanisms of gas-water EB flow in transparent experimental boreholes during production logging, combined with an analysis of the production log response characteristics and experimental production logging flow pattern maps, a method for flow pattern identification relying on log responses and a drift-flux model were proposed for gas-water EB flow. This model, built upon experimental data of EB flow, reveals physical mechanisms of gas-water EB flow during measurement processing. The coefficients it contains are the specific values under experimental conditions and with the PLT string used in our experiments. These coefficients also reveal the interference with original downhole flow patterns by the PLT string. Due to the representativeness that our simulated flow experiments and PLT string possess, the model coefficients can be applied as empirical values of logging interpretation model parameters directly to real production logging data interpretation, when the measurement circumstances and PLT strings are similar.

Evolution of Polymer Melt Conformation and Entanglement under High-Rate Elongational Flow

Using molecular dynamics(MD)simulations,this study explores the fluid properties of three polymer melts with the same number of entanglements,Z,achieved by adjusting the entanglement length Ne,while investigating the evolution of polymer melt conformation and entanglement under high-rate elongational flow.The identification of a master curve indicates consistent normalized linear viscoelastic behavior.Surprising findings regarding the steady-state viscosity at various elongational rates(Wi_(R)>4.7)for polymer melts with the same Z have been uncovered,challenging existing tube models.Nevertheless,the study demonstrates the potential for normalizing the steady-state elongational viscosity at high rates(Wi_(R)>4.7)by scaling with the square of the chain contour length.Additionally,the observed independence of viscosity on the elongational rate at high rates suggests that higher rates lead to a more significant alignment of polymer chains,a decrease in entanglement,and a stretching in contour length of polymer chains.Molecular-level tracking of tagged chains further supports the assumption of no entanglement under rapid elongation,emphasizing the need for further research on disentanglement in polymer melts subjected to high-rate elongational flow.These results carry significant implications for understanding and predicting the behavior of polymer melts under high-rate elongational flow conditions.