Distribution and treatment of harmful gas from heavy oil production in the Liaohe Oilfield, Northeast China

The distribution and treatment of harmful gas （H2S） in the Liaohe Oilfield, Northeast China, were investigated in this study. It was found that abundant toxic gas （H2S） is generated in thermal recovery of heavy oil. The H2S gas is mainly formed during thermochemical sulfate reduction （TSR） occurring in oil reservoirs or the thermal decomposition of sulfocompounds （TDS） in crude oil. H2S generation is controlled by thermal recovery time, temperature and the injected chemical compounds. The quantity of SO4^2- in the injected compounds is the most influencing factor for the rate of TSR reaction. Therefore, for prevention of H2S formation, periodic and effective monitoring should be undertaken and adequate H2S absorbent should also be provided during thermal recovery of heavy oil. The result suggests that great efforts should be made to reduce the SO4^2- source in heavy oil recovery, so as to restrain H2S generation in reservoirs. In situ burning or desulfurizer adsorption are suggested to reduce H2S levels. Prediction and prevention of H2S are important in heavy oil production. This will minimize environmental and human health risks, as well as equipment corrosion.

An improved coupled flow-geomechanical model for cyclic steam stimulation

Considering the pore deformation and permeability changes during dilation-recompaction in cyclic steam stimulation(CSS),an existing geomechanical model is improved and thermo-mechanically coupled with the flow equations to form a coupled flow-geomechanical model.The impacts of dilation-recompaction parameters can be quantified through sensitivity analysis and uncertainty assessment utilizing the synergy between Latin hypercube designs and response surface methodology.The improved coupled flow-geomechanical model allows a more reasonable history-matching of steam injection pressure and volume and oil/water production volume.In both the linear and quadratic models,the rise in recompaction pressure has the most significant effect on the rise in the volumes of steam injection and water production,both rock compressibility and recompaction pressure are positively correlated with steam injectivity and oil/water production,and the dilation pressure is negatively correlated with steam injectivity and oil/water production.In the linear model,dilation pressure has the most significant negative impact on the cumulative oil production,and compressibility and recompaction pressure are positively correlated with oil production.In the quadratic model,the rise in recompaction pressure has the most significant effect on the rise in the cumulative volumes of oil/water production and steam injection.The interactions between the dilation/recompaction pressures and spongy-rock compressibility negatively affect the cumulative volumes of oil/water production and steam injection.

Energy dependence of resonance production in relativistic heavy ion collisions

The production of the hadronic resonances K^＊0（892）,φ（1020）,∑^＊（1385）,and Ξ^＊（1530） in central AA collisions at √SNN=17.3,200,and 2760 GeV is systematically studied.The direct production of these resonances at system hadronization is described by the quark combination model and the effects of hadron multiple-scattering stage are dealt with by a ultra-relativistic quantum molecular dynamics model（UrQMD）.We study the contribution of these two production sources to final observation and compare the final spectra with the available experimental data.The pT spectra of K^＊0（892） calculated directly by quark combination model are explicitly higher than the data at low pT≤1.5 GeV,and taking into account the modification of rescattering effects,the resulting final spectra well agree with the data at all three collision energies.The rescattering effect on φ（1020） production is weak and including it can slightly improve our description at low p_T on the basis of overall agreement with the data.We also predict the pT spectra of ∑^＊（1385） and Ξ^＊（1530）,to be tested by the future experimental data.

Search for the doubly heavy baryons Ω^(0)_(bc) and E^(0)_(bc) decaying to Λ^(+)_(c)π^(-) and E^(+)_(c)π^(-)

The first search for the doubly heavyΩ^(0)_(bc)baryon and a search for the E^(0)_(bc)baryon are performed using pp collision data collected via the LHCb experiment from 2016 to 2018 at a centre-of-mass energy of 13 TeV,corresponding to an integrated luminosity of 5.2 fb^(-1).The baryons are reconstructed via their decays to Λ^(+)_(c)π^(-)and E^(+)_(c)π^(-).No significant excess is fbund for invariant masses between 6700 and 7300 MeV/c^(2),in a rapidity range from 2.0 to 4.5 and a transverse momentum range from 2 to 20 MeV/c.Upper limits are set on the ratio of the Ω^(0)_(bc)and E^(0)_(bc)production cross-section times the branching fraction to Λ^(+)_(c)π^(-)(E^(+)_(c)π^(-))relative to that of the Λ^(0)_(b)(E^(0)_(b))baryon,for different lifetime hypotheses,at 95%confidence level.The upper limits range from 0.5 x 10^(-4)to 2.5 x 10^(-4)for theΩ^(0)_(bc)→Λ^(+)_(c)π^(-)(E^(0)_(bc)→Λ^(+)_(c)π^(-))decay,and from 1.4x 10^(-3)to 6.9 x 10^(-3)for theΩ^(0)_(bc)→E^(+)_(c)π^(-)(E^(0)_(bc)→E^(+)_(c)π^(-))decay,depending on the considered mass and lifetime of theΩ^(0)_(bc)(E^(0)_(bc))baryon.

Recent results on strangeness,charm and beauty production at HERA

Based on the data collected with the H1 and ZEUS detectors at HERA, recent results on strangeness, charm and beauty production in ep collision are presented.

Λb^0-baryon production in pp collisions in the general-mass variable-flavour-number scheme,and comparison with CMS and LHCb data

We calculate the next-to-leading-order cross section for the inclusive production ofΛ（b ）baryons in pp collisions in the general-mass variable-flavor-number scheme.We use realistic evolved non-perturbative fragmentation functions obtained from fits to B-meson production in e^＋e^-annihilation and compare our results for transversemomentum and rapidity distributions with recent experimental data from the CMS and the LHCb collaborations at the CERN LHC.We find satisfactory agreement in general,with some indication for the need to modify the available fragmentation functions at larger values of the scale variable.