Recent research has highlighted a growing focus on stimuli-responsive surfactant wormlike micelles (WLMs), particularly those with switchability. Here we report CO2-switchable WLMs based on the commercial anionic surfactant sodium dodecyl sulfate (SDS) and N,N,N',N'-tetramethyl-1,3-propanediamine (TMPDA) mixed in a mole ratio of 2:1. When CO2 is bubbled into an aqueous mixture of these reactants, the TMPDA molecules are protonated to form quaternary ammonium species, two of which in the same protonated TMPDA molecule "bridge" two SDS molecules by noncovalent electrostatic attraction, behaving like a pseudogemini surfactant and forming viscoelastic WLMs as verified by cryo-TEM. Upon removal of CO2, the quaternized spacers are deprotonated back to tertiary amines, dissociating the pseudogeminis back to conventional SDS molecules that form low-viscosity spherical micelles. Such a reversible sphere-to-worm transition could be repeated several cycles without a loss of response to CO2.

We investigate a Bose-Einstein condensate strongly coupled to an optical cavity via a repulsive optical lattice. We detect a stable self-ordered phase in this regime, and show that the atoms order through an antisymmetric coupling to the P-band of the lattice, limiting the extent of the phase and changing the geometry of the emergent density modulation. Furthermore, we find a non-equilibrium phase with repeated intense bursts of the intra-cavity photon number, indicating non-trivial driven-dissipative dynamics. arXiv:1905.10377v1 [cond-mat.quant-gas]

With the depletion of light oil, heavy oil is becoming one of the most promising resources for meeting future energy consumption. Heavy oil resources are abundant, but the traditional water flooding method can only achieve less than 20% of heavy oil recovery. Thermal recovery has proven effective in producing heavy oil, but not suitable for many heavy oil formations that are either thin or buried deep underground. Carbon Dioxide injection is a ‘win‐win’ enhanced oil recovery (EOR) technique for many heavy oil fields. Injected CO2 not only increases heavy oil output, but also traps injected CO2 underground. Carbon dioxide effectively recovers heavy oil thanks to several mechanisms, including oil swelling, viscosity reduction, and blow‐down recovery. This review discusses the advances of CO2 flooding at both laboratory scale and field scale. Laboratory tests show that CO2 can significantly improve heavy oil recovery. Several field cases in the USA, Turkey, Trinidad, and China are reviewed. Field experiences show that CO2 flooding is a successful EOR method for heavy oil fields. However, some issues were encountered in field applications, such as early gas breakthrough, corrosion, CO2 availability, and high costs.

We realize a non-degenerate two-mode Dicke model with competing interactions in a Bose-Einstein condensate (BEC) coupled to two orthogonal polarization modes of a single optical cavity. The BEC is coupled to the cavity modes via the scalar and vectorial part of the atomic polarizability. We can independently change these couplings and determine their effect on a self-organization phase transition. Measuring the phases of the system, we characterize a crossover from a single-mode to a two-mode Dicke model. This work provides perspectives for the realization of coupled phases of spin and density. arXiv:1902.09831v1 [cond-mat.quant-gas]

Gas injection into tight oil reservoirs, as a secondary recovery technique, can be favorable and promising in terms of high gas injectivity and good displacement/sweeping efficiency over water injection. Particularly, CO2 injection is the best option due to its superior miscibility effect with oil and in consideration of geological storage of the greenhouse gas. In this study, CO2 injection into a tight oil reservoir for IOR is assessed and a pilot project is underway. The reservoir is located in the G89 Block of Shengli Oilfield East China, which has very poor water injectivity due to very low permeability of less than 5 mD in average, and has been producing via natural depletion since 2005. The original reservoir pressure was over 40 MPa, and the reservoir temperature of 126  . A CO2 injection and storage program has been proposed, and CO2 will be from a coal-fired power plant 30 km away under a Sinopec’s CCS (Carbon Capture and Storage) scheme. Laboratory investigation includes PVT experiments, slim tube test and core flooding/displacement experiments, in order to study the miscibility effect and displacement efficiency via CO2 injection at various conditions. Reservoir simulations were performed to predict the IOR potentials of CO2 injection at different pressures, namely at immiscible, miscible and near-miscible modes. The MMP (Minimum Miscibility Pressure) of the reservoir oil is determined as over 29 MPa, while the reservoir pressure at the beginning of CO2 injection was around 23 MPa after several years’ depletion. Therefore, CO2 flooding at a near miscible mode will prevail. A field pilot of CO2 injection at current reservoir conditions (at near-miscible mode) is designed and its performance is presented in the paper.