Long-term and widespread use of plastic mulching has led to the accumulation of residual plastic film(RPF)in farmland soils of Xinjiang,China.However,there is no specific quantitative basis for RPF pollution or a clea...Long-term and widespread use of plastic mulching has led to the accumulation of residual plastic film(RPF)in farmland soils of Xinjiang,China.However,there is no specific quantitative basis for RPF pollution or a clear understanding of the influence of residual film on crop growth.The aim of this study was to investigate the effect of RPF on the growth of cotton,an important cash crop of Xinjiang.Based on the field conditions and previous reports,various amount of residual film was applied in 0-30 cm soil layer.The growth index including emergence rate,dry matter,and yield of cotton was examined at different growth stages under different soil residual film levels.Results demonstrated a significant effect of RPF on soil moisture distribution and movement.Plastic residues had a significant effect on cotton growth at levels above 200 kg/hm2,and the yield decreased as the RPF amount increased.Based on these findings,200 kg/hm2 was suggested as a threshold level to determine the effects of RPF on cotton.This study provided a basis to rate RPF pollution in farmland soils and help understand the impact of pollution on crop productivity.展开更多
Weakly consolidated reservoirs are prone to sand production problem,which can lead to equipment damages and environmental issues.The conditions for sand production depend on stresses and properties of rock and fluid.A...Weakly consolidated reservoirs are prone to sand production problem,which can lead to equipment damages and environmental issues.The conditions for sand production depend on stresses and properties of rock and fluid.Accurate sand volume estimation is,however,still a challenging issue,especially for reservoirs in weak formations.The weak reservoirs containing viscous or heavy oil are mainly discovered in shallow depths in Kazakhstan,with moderate temperature and pressure.Many prediction models developed for open-hole completions where the reservoir materials usually possess certain strength are not applicable for the local reservoirs where the materials are significantly weaker even if casing is used to support the wellbore with oil produced through the perforation tunnels.In this context,a prediction model was proposed where the volume of the produced sand was estimated as the volume of the plastic zone of the failed materials surrounding the perforation tunnels.The model assumes an evolving truncated conical shape for the damage zone and takes into account stress distributions and shear failure in this zone.Then,the proposed model was used to estimate sand volumes in 20 wells during oil production with sequential increase of flow rates.The predictions match well with the measured sand volumes in a local oil field.Finally,a sensitivity analysis was conducted on the model performance.It shows that the permeability of the plastic zone was the most significant controlling factor in the prediction results.展开更多
基金This work was financially supported by National key R&D plan of China(No.2017YFD0701102)the Corps key R&D projects(No.2019AB007)+2 种基金the Special Fund for Agroscientific Research in the Public Interest(No.201503105)and the National Natural Science Foundation of China(Grant No.11562019)The authors are grateful to the farmers of the trial area for their cooperation.
文摘Long-term and widespread use of plastic mulching has led to the accumulation of residual plastic film(RPF)in farmland soils of Xinjiang,China.However,there is no specific quantitative basis for RPF pollution or a clear understanding of the influence of residual film on crop growth.The aim of this study was to investigate the effect of RPF on the growth of cotton,an important cash crop of Xinjiang.Based on the field conditions and previous reports,various amount of residual film was applied in 0-30 cm soil layer.The growth index including emergence rate,dry matter,and yield of cotton was examined at different growth stages under different soil residual film levels.Results demonstrated a significant effect of RPF on soil moisture distribution and movement.Plastic residues had a significant effect on cotton growth at levels above 200 kg/hm2,and the yield decreased as the RPF amount increased.Based on these findings,200 kg/hm2 was suggested as a threshold level to determine the effects of RPF on cotton.This study provided a basis to rate RPF pollution in farmland soils and help understand the impact of pollution on crop productivity.
基金sponsored by a Nazarbayev University research grant
文摘Weakly consolidated reservoirs are prone to sand production problem,which can lead to equipment damages and environmental issues.The conditions for sand production depend on stresses and properties of rock and fluid.Accurate sand volume estimation is,however,still a challenging issue,especially for reservoirs in weak formations.The weak reservoirs containing viscous or heavy oil are mainly discovered in shallow depths in Kazakhstan,with moderate temperature and pressure.Many prediction models developed for open-hole completions where the reservoir materials usually possess certain strength are not applicable for the local reservoirs where the materials are significantly weaker even if casing is used to support the wellbore with oil produced through the perforation tunnels.In this context,a prediction model was proposed where the volume of the produced sand was estimated as the volume of the plastic zone of the failed materials surrounding the perforation tunnels.The model assumes an evolving truncated conical shape for the damage zone and takes into account stress distributions and shear failure in this zone.Then,the proposed model was used to estimate sand volumes in 20 wells during oil production with sequential increase of flow rates.The predictions match well with the measured sand volumes in a local oil field.Finally,a sensitivity analysis was conducted on the model performance.It shows that the permeability of the plastic zone was the most significant controlling factor in the prediction results.
