ZnS:Er quantum dots were prepared in aqueous medium from readily available precursors. The construction, morphology and luminescence properties of the ZnS:Er quantum dots were evaluated by X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescence spectra. The average particle size was calculated using the Scherrer formula to be 4 nm, which is also observed from high resolution transmission electron microscopy (HRTEM) image. Different laser wavelengths at 976 +/- 2 nm and 1480 nm were utilized as the excitation source. ZnS:Er quantum dots had a fluorescence spectrum in 1550 nm region through the 4I13/2 --> 4I15/2 transition. Furthermore, intensity increased with increasing excitation intensity and dopant concentration. The reason for the photoluminescence spectra broadening is discussed. It is because the energy levels of Er3+ are split by a coulombic interaction between electrons, including spin correction and spin-orbit coupling, and eventually by the Stark effect due to ZnS QDs crystal field and local coordination.

Si 4+ -doped BaZr(BO 3 ) 2 :Eu 3+ phosphors are prepared by a conventional solid-state reaction. The influence of Si 4+ addition on the charge transfer state of Eu 3+ -O 2-and photoluminescence (PL) properties of BaZr(BO 3 ) 2 :Eu 3+ are discussed. Room temperature PL spectra indicated that efficient emission is obtained by Si doping. Increased values for the peak-peak ratio (PPR) of BaZr(BO 3 ) 2 :Eu 3+ at higher Si doping concentrations implied that the Eu 3+ ion is located in a more asymmetric environment in BaZr 0.8 Si 0.2 (BO 3 ) 2 :Eu 3+ than in the undoped samples. The Judd-Ofelt parameters Ω λ (λ=2,4) were calculated from the PL data, giving results that were consistent with those from the PPR. The maximum radiative quantum efficiency was achieved at a Si doping concentration of 20 mol%. BaZr(BO 3 ) 2 :Eu 3+ , charge transfer state, peak-peak ratio, Judd-Ofelt theory Citation: Zhang Z P, Li G M, Zhang X S, et al. Structural investigation and luminescent properties of BaZr(BO 3 ) 2 :Eu 3+ phosphors containing Si.In recent years, many researchers have focused on improving the luminescence properties of traditional materials [1-3] and preparing new luminescent phosphors with high performance [4,5]. Xing et al. [3] reported an enhancement of the luminescent intensity of Gd 2 O 2 S:Tb phosphors through the use of a new synthetic method. Luo et al.[5] reviewed the recent progress in alkaline earth silicate host luminescent materials with broad excitation bands for phosphor-converted white light emitting diodes. Borate-based systems have the advantages of low synthesis temperature, high UV transparency and good thermal stability. Eu 3+ is commonly adopted as an activator in commercial red phosphors [1,2]. There are two main radiative transitions that occur in the 4f levels of Eu 3+ . The emission centered at 591 nm is caused by a magnetic dipole transition of 5 D 0 -7 F 1 and

Er3+-doped 25BaO-(25-x)SiO2-xAl2O3-25B2O3 transparent glasses are prepared with x = 0, 12.5 and 25 by a solid-state reaction. The Er-related NIR luminescence intensity, which corresponds to the transition of 4I15/2-4I13/2, is obviously altered with different silicon/aluminum ratios. The Judd-Ofelt parameters of the Er3+ ions are adopted to explain the intensity change in the NIR fluorescence, and the Raman scattering intensity versus the amount of Al and/or Si components are discussed. The spectra of the three samples are quite similar in the peak positions, but different in intensity. The maximal phonon density of state for the samples is calculated from the Raman spectra and is correlated to the NIR luminescence efficiency.

Si4+ and Al3+ doped BaZr(BO3)2:Eu phosphors were prepared by solidstate reaction. BaZr(BO3)2:Eu3+, BaZr(BO3)2:Eu3+, Si4+ and BaZr(BO3)2:Eu3+, Al3+ were characterized by X-ray diffraction spectra (XRD) and photoluminescence spectra. After codoped with Si or Al, the charge-transfer state (CTS) band of Eu3+-O(2-) shows blue shift accompanied by increasing intensity due to shorter ionic radius and stronger electro negativity of Si or Al compared with Zr4+. The high value of asymmetric ratio R(2-1) and omega2 of BaZr(BO3)2:Eu3+ with Si or Al codoping indicates a less symmetrical local structure of Eu3+. This implies that the quantum efficiencies of the 5D0 level of these complexes can be enhanced by doping with Si and Al respectively. Calculation of the Judd-Ofelt parameters of Eu3+ under different crystal fields gives similar results.

In many matured fields around the world, the infill well development faces multiple challenges; reservoir depletion caused by existing wells is unavoidable, the remaining area to be targeted by infill is typically relatively marginal, with thinner formations that still bear significant subsurface uncertainty compared with sweet spot area developed in the initial phase. In addition, some fields are impacted by PSC conditions, with a strict time constraint. When developing infill wells several key aspects have to be considered: starting from potential severe mud losses, drill pipe stuck during the drilling phase, to formation damage, production interference with neighboring wells, earlier load up for gas wells etc. Shell China developed an integrated approach by considering all these challenges, and successfully implemented it for the Changbei tight gas infill well project. During the Design Phase, a series of core lab tests were carried out to evaluate the formation damage and related permeability reduction. The lab test results indicated that the permeability reduction as result of water encroaching into water wet rock formation is significant (+90%), causing a "water locking" effect. Another topic pertaining to the Desing phase in the Changbei field is the optimisation of the dual lateral well trajectory based on the expected depletion state of the reservoir. Also discussed is the horizontal well tubing size optimization, which accounted for the selection matrix based on KH, online date (related to PSC end) and expected reservoir pressure (depleted). In the Delivery phase, the surfactant additive identified through the lab testing has been used into the drilling mud and completion fluid to appropriately mitigate the water locking effect. The lab test results demonstrated that a permeability improvement of at least 10% could be achieved. Furthermore, the surfactant concentration was optimized to maximise the emulsion effect for water treatment and the foaming effect during the drilling phase. This paper also covers the well flowback efficiency improvement achieved by additional nitrogen lifting and prolonged firing time. During the Well Reservoir and Facility Management phase (WRFM), a study of infill well production interference with existing wells was carried out and the recovery could be maximized at the cluster level.