Experimental investigation on the enhanced oil recovery efficiency of polymeric surfactant: Matching relationship with core and emulsification ability

The polymeric surfactant can be used as an efficient agent for enhanced oil recovery(EOR)because of its large bulk viscosity and good interfacial activity.However,there is a sparse understanding of its matching relationship with reservoirs and emulsification occurrence conditions,which may affect its migration and EOR efficiency.One intermolecular association molecule polymeric surfactant(IAM)was synthesized by micellar polymerization and characterized with 1 H NMR,FTIR,and TGA.The matching relationship between IAM and reservoirs was evaluated by comparing the viscosity retention rate of effluent in the core flow experiments.Moreover,the effect of the matching relationship on EOR in the heterogeneous reservoir was clarified with parallel core displacement experiments by considering different flow abilities of IAM in the high-permeability layer.The occurrence conditions of in-situ emulsification of IAM were evaluated via oil-water co-injection experiments under the different injection rates and oil-water ratios.Microscopic visualization displacement was carried out to compare the micro EOR mechanisms of different chemical systems.The results show that IAM features thickening,shearing resistance,viscoelasticity,thermal stability,and interfacial activity.The matching relationship between cores and IAM could be divided as hardly injected,flow limited,and flow smoothly,corresponding to the viscosity retention ratio of<20%,20%-80%,and>80%,respectively.IAM could gain better EOR efficiency(17.69%)when its matching relationship to the high permeability layer was“flow limited”.The defined mixture capillary number shows that only when it is greater than 1×10^(3),the in-situ emulsions can be generated.Compared to HPAM,IAM could reduce IFT and form vortices to more effectively displace film and corner remaining oils by stripping and peeling off crude oil.The formed emulsion accumulated at the pore throat could further increase flow resistance,which benefits swept area enlargement.This work could provide theoretical and data support for the parameters design in the polymeric surfactant practical application.

Failure mechanism and influencing factors of cement sheath integrity under alternating pressure

The failure of cement sheath integrity can be easily caused by alternating pressure during large-scale multistage hydraulic fracturing in shale-gas well.An elastic-plastic mechanical model of casing-cement sheath-formation(CSF)system under alternating pressure is established based on the Mohr-Coulomb criterion and thick-walled cylinder theory,and it has been solved by MATLAB programming combining global optimization algorithm with Global Search.The failure mechanism of cement sheath integrity is investigated,by which it can be seen that the formation of interface debonding is mainly related to the plastic strain accumulation,and there is a risk of interface debonding under alternating pressure,once the cement sheath enters plasticity whether in shallow or deep well sections.The matching relationship between the mechanical parameters(elastic modulus and Poisson's ratio)of cement sheath and its integrity failure under alternating pressure in whole well sections is studied,by which it has been found there is a“critical range”in the Poisson's ratio of cement sheath.When the Poisson's ratio is below the“critical range”,there is a positive correlation between the yield internal pressure of cement sheath(SYP)and its elastic modulus.However,when the Poisson's ratio is above the“critical range”,there is a negative correlation.The elastic modulus of cement sheath is closely related to its Poisson's ratio,and restricts each other.Scientific and reasonable matching between mechanical parameters of cement sheath and CSF system under different working conditions can not only reduce the cost,but also protect the cement sheath integrity.

Coordinated development of land multi-function space: An analytical framework for matching the supply of resources and environment with the use of land space for ecological protection, agricultural production and urban construction

Based on the carrying capacity of the resources and the environment,this article defines the connotation of the land multifunctional space(LMFS)from three aspects,ecological protection,agricultural production and urban construction,in the new era of land space planning system.Moreover,a framework is constructed for the coordinated development of the multi-functional oriented space to match the use of land space(ULS)with the supply of resources and environment(SRE).Based on this,the technology and methods of comprehensive evaluation,dominance recognition,and matching relationship division functions of the use of land space(FULS)and functions of the supply of resources and environment(FSRE)are discussed.The advantageous functions of the use of land space(AFULS)and advantageous functions of the supply of resources and environment(AFSRE)are also identified in the study area.A LMFS coordinated development system integrating“function position-comprehensive partition-regulation strategy”is proposed.Through the empirical study of Shandong province,we found that,first,the FULS of ecological protection space in the province is mainly found in high value areas,and the FSRE is mainly in low value areas,which has certain complementarity in the space.The FULS of agricultural production space is mainly observed in high value areas,the FSRE is mainly in middle value areas,and the spatial distribution is balanced and staggered.The FULS of the urban construction space and the FSRE are mainly in middle values areas,and the spatial distribution is basically similar.Second,the FULS in the study area is dominated by the single advantage of agricultural production and urban construction,while the FSRE has a relatively balanced distribution of the advantages of ecological protection,single agricultural production and compound advantages of agricultural production and urban construction,and urban construction and ecological protection.The matching between the two is mainly at high and middle levels.Specifically,70%of the province’s land space still has a certain development and utilization potential,and 30%of ULS intensity is close to or exceeds the resource and environment carrying capacity.Third,considering the comprehensive impact of resource endowment,social and economic development and policy and institutional environment on different matching relationships,this paper constructs the land spatial development strategic pattern of“two screens-seven regions-multicore”positioning and“four regions-eight categories”hierarchical area of Shandong at the macro level,and puts forward a differentiated land space development strategy.

A global model for evaluating discharge characteristics and performance of hollow cathodes

Hollow cathode,with the highest plasma density,current density,and temperature,becomes one of the most important components in the electro-thruster system.As the electric-propulsion thruster performance is directly related to the ionization rate,reliability,and lifetime of the hollow cathode,this paper develops a global model to study the effects of discharge current,gas flow rate,and gas species on the discharge characteristics in the insert and orifice regions of the hollow cathode.The emitter wall temperatures of hollow cathodes predicted by the global model are compared with experimental results from NSTAR thruster neutralization cathodes,confirming the model's validity.The influence of hollow cathode emitter material and structure sizes on the plasma parameters in the internal regions was also evaluated.The simulation results show that there is an optimal matching relationship between the discharge current and gas flow rate to guarantee the maximum ionization rate.The optimal working region for the hollow cathode has been deter-mined under different energetic,regime and structural parameters.The global model established in this paper can quickly determine the key structure and operating parameters of hollow cathode at the design stage,and provide the theoretical basis for hollow cathode design and development.

Matching mechanism analysis on an adaptive cycle engine

As a novel aero-engine concept,adaptive cycle aero-engines（ACEs） are attracting wide attention in the international aviation industry due to their potential superior task adaptability along a wide flight regime.However,this superior task adaptability can only be demonstrated through proper combined engine control schedule design.It has resulted in an urgent need to investigate the effect of each variable geometry modulation on engine performance and stability.Thus,the aim of this paper is to predict and discuss the effect of each variable geometry modulation on the matching relationship between engine components as well as the overall engine performance at different operating modes,on the basis of a newly developed nonlinear component-based ACE performance model.Results show that at all four working modes,turning down the high pressure compressor variable stator vane,the low pressure turbine variable nozzle,the nozzle throat area,and turning up the core-driven fan stage variable stator vane,the high pressure turbine variable nozzle can increase the thrust at the expense of a higher high pressure turbine inlet total temperature.However,the influences of these adjustments on the trends of various engine components＇ working points and working lines as well as the ratio of the rotation speed difference are different from each other.The above results provide valuable guidance and advice for engine combined control schedule design.