Based on the literature and experimental results, three kinds of amendments, namely, rice biochar, hydroxyapatite and potassium dihydrogen phosphate(KH2PO4), and deeper ploughing were selected to evaluate the field ap...Based on the literature and experimental results, three kinds of amendments, namely, rice biochar, hydroxyapatite and potassium dihydrogen phosphate(KH2PO4), and deeper ploughing were selected to evaluate the field application effect of soil amendments and agronomic measures on the remediation of Cd contamination in greenhouses. Cd-contaminated greenhouse screening was conducted from 2015 to 2017. In September 2017, comparative tests of eight treatments were performed in September 2017, and a selective test was performed in September 2018. The results of the screening of contaminated areas indicated that the distributions of over-standard sites and Cd content were significantly different. Greenhouse No. 4, in which the highest over-standard rate was 83.33% and the average content of Cd in soil was 0.535 mg/kg, was used as a comparative test experimental site for eight treatments. Greenhouse No. 1 was selected as the optimum test greenhouse for selective testing, with three plots having average Cd concentrations of 0.530, 0.568 and 0.792 mg/kg. The 8 months following comparative treatment showed that the content of available Cd following the treatment of rice biochar+hydroxyapatite+deeper ploughing(treatment T6) was reduced by 32.55% and 24.96% compared with the CK(the control) and 2 months following treatment, respectively. The content of available Cd using rice biochar+KH2PO4+deeper ploughing(treatment T7) treatment decreased by 47.88% and 31.00% compared with the CK and 2 months following treatment. The selective test results showed that in rice biochar+hydroxyapatite+deeper ploughing: the total Cd content of decreased from 0.489 to 0.372 mg/kg(23.86% lower), compared with the CK, and the mean content of available Cd decreased by 10.71% after 8 months, which was the lowest available Cd measured(0.133 mg/kg). In addition, the bean plant Cd content, bioconcentration factor(BCF) and translocation coefficient(TF) decreased by 15.86%, 23.68% and 25.77%, respectively. Rice biochar+hydroxyapatite+deeper ploughing is a favoured technology for the remediation of Cd-contaminated protected vegetable fields.展开更多
According to the investigation and analysis of the production situation of horizontal wells in major oilfields at home and abroad, there are five types of accidents in horizontal wells, namely, blockage caused by fall...According to the investigation and analysis of the production situation of horizontal wells in major oilfields at home and abroad, there are five types of accidents in horizontal wells, namely, blockage caused by falling objects, blockage caused by string breaking, blockage caused by downhole tools, blockage caused by casing damage and other types of failures. Influenced by factors such as large angle of inclination, long horizontal section and large curvature of borehole, there are six technical difficulties in the process of horizontal well overhaul, such as difficulty in fishing, difficulty in running and pulling out large-diameter tools, serious weight loss on bit, easy wear of lead mold, high friction between string and casing, and difficulty in sand production. Therefore, the technical countermeasures are studied, including the fishing technology of horizontal well, drilling and grinding technology of horizontal well, continuous sand washing technology of horizontal well, etc. The composition, technical principle and construction technology of key pipe strings are analyzed and studied. Taking L Oilfield as an example, the application effect of horizontal well overhaul technology is analyzed. The obtained results and knowledge can provide reference experience for peers.展开更多
基金Supported by National Key Research and Development project(2016YFD0801003)Hebei Province Modern Agricultural Industry Technology System Vegetable Industry Innovation Team Project(HBCT2018030206)+1 种基金Talents Engineering Training Project of Hebei Province(A201803030)Hebei Province Innovation Capability Enhancement Plan Project(19244010D)。
文摘Based on the literature and experimental results, three kinds of amendments, namely, rice biochar, hydroxyapatite and potassium dihydrogen phosphate(KH2PO4), and deeper ploughing were selected to evaluate the field application effect of soil amendments and agronomic measures on the remediation of Cd contamination in greenhouses. Cd-contaminated greenhouse screening was conducted from 2015 to 2017. In September 2017, comparative tests of eight treatments were performed in September 2017, and a selective test was performed in September 2018. The results of the screening of contaminated areas indicated that the distributions of over-standard sites and Cd content were significantly different. Greenhouse No. 4, in which the highest over-standard rate was 83.33% and the average content of Cd in soil was 0.535 mg/kg, was used as a comparative test experimental site for eight treatments. Greenhouse No. 1 was selected as the optimum test greenhouse for selective testing, with three plots having average Cd concentrations of 0.530, 0.568 and 0.792 mg/kg. The 8 months following comparative treatment showed that the content of available Cd following the treatment of rice biochar+hydroxyapatite+deeper ploughing(treatment T6) was reduced by 32.55% and 24.96% compared with the CK(the control) and 2 months following treatment, respectively. The content of available Cd using rice biochar+KH2PO4+deeper ploughing(treatment T7) treatment decreased by 47.88% and 31.00% compared with the CK and 2 months following treatment. The selective test results showed that in rice biochar+hydroxyapatite+deeper ploughing: the total Cd content of decreased from 0.489 to 0.372 mg/kg(23.86% lower), compared with the CK, and the mean content of available Cd decreased by 10.71% after 8 months, which was the lowest available Cd measured(0.133 mg/kg). In addition, the bean plant Cd content, bioconcentration factor(BCF) and translocation coefficient(TF) decreased by 15.86%, 23.68% and 25.77%, respectively. Rice biochar+hydroxyapatite+deeper ploughing is a favoured technology for the remediation of Cd-contaminated protected vegetable fields.
文摘According to the investigation and analysis of the production situation of horizontal wells in major oilfields at home and abroad, there are five types of accidents in horizontal wells, namely, blockage caused by falling objects, blockage caused by string breaking, blockage caused by downhole tools, blockage caused by casing damage and other types of failures. Influenced by factors such as large angle of inclination, long horizontal section and large curvature of borehole, there are six technical difficulties in the process of horizontal well overhaul, such as difficulty in fishing, difficulty in running and pulling out large-diameter tools, serious weight loss on bit, easy wear of lead mold, high friction between string and casing, and difficulty in sand production. Therefore, the technical countermeasures are studied, including the fishing technology of horizontal well, drilling and grinding technology of horizontal well, continuous sand washing technology of horizontal well, etc. The composition, technical principle and construction technology of key pipe strings are analyzed and studied. Taking L Oilfield as an example, the application effect of horizontal well overhaul technology is analyzed. The obtained results and knowledge can provide reference experience for peers.
