Aiming at the problem that the existing risk assessment methods in China cannot simply and accurately assess the safety risk of gas wells, a rapid semi-quantitative risk assessment method for gas wells under high temp...Aiming at the problem that the existing risk assessment methods in China cannot simply and accurately assess the safety risk of gas wells, a rapid semi-quantitative risk assessment method for gas wells under high temperature and pressure is studied. Based on the rapid risk assessment method of annulus well with pressure in Chevron Company and the existing risk assessment methods, the well barrier and annulus pressure of high temperature and high pressure gas wells are fully considered. A rapid semi-quantitative risk assessment method for high temperature and high pressure gas wells is established, which takes the annulus pressure value, well service life, annulus pressure recovery after pressure relief, reservoir conditions (formation pressure, production) and well CO<sub style="font-family:" white-space:normal;"=""><span style="font-size:12px;font-family:Verdana;">2 </span></sub><span style="font-family:Verdana;">and H</span><sub style="font-family:" white-space:normal;"=""><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">S content as the key risk indexes. The method is applied in a gas field, and the risk value and risk grade of a practical well are semi-quantitatively evaluated. The overall risk situation of the well is obtained. The research results provide important technical guidance for the safe production of gas well.</span>展开更多
Objective To understand the occurrence and distribution of Campylobacter jejuni in chicken in China, assess its health risk to the Chinese population, and provide recommendations for effective risk control. Methods Da...Objective To understand the occurrence and distribution of Campylobacter jejuni in chicken in China, assess its health risk to the Chinese population, and provide recommendations for effective risk control. Methods Data from the National Food Safety Risk Surveillance Network on Campylobacter jejuni between 2007 and 2010 and from published articles were analyzed. Eleven parameters were used based on the whole chicken preparation process and prevalence of Campylobocter jejuni for risk assessment by using the Ross-Sumner Method. Results The detection rates of Campylobacterjejuni in raw chicken were between 0.29% and 2.28% during 2007-2010 in China （more than 20 provinces）. The probability of illness caused by Campylobacter jejuni due to chicken consumption was around six out of one million consumers per day in urban areas and around one out of one million consumers per day in rural areas. Total predicted illnesses per year was about 736 000, accounting for 1.6‰ of the general population in urban areas and about 301 000, accounting for 0.37‰ of the total population in rural areas. The risk rankings of Campylobocterjejuni in chicken were 52 and 49 in urban and rural areas, respectively. Conclusion A high risk score for Campylobacterjejuni in chicken was obtained in China. This result may contribute to development of food safety management strategies. Key efforts should be made to control the risk of Campylobacterjejuni in chicken in China, especially in chick breeding and chicken preparation processes.展开更多
文摘Aiming at the problem that the existing risk assessment methods in China cannot simply and accurately assess the safety risk of gas wells, a rapid semi-quantitative risk assessment method for gas wells under high temperature and pressure is studied. Based on the rapid risk assessment method of annulus well with pressure in Chevron Company and the existing risk assessment methods, the well barrier and annulus pressure of high temperature and high pressure gas wells are fully considered. A rapid semi-quantitative risk assessment method for high temperature and high pressure gas wells is established, which takes the annulus pressure value, well service life, annulus pressure recovery after pressure relief, reservoir conditions (formation pressure, production) and well CO<sub style="font-family:" white-space:normal;"=""><span style="font-size:12px;font-family:Verdana;">2 </span></sub><span style="font-family:Verdana;">and H</span><sub style="font-family:" white-space:normal;"=""><span style="font-size:12px;font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">S content as the key risk indexes. The method is applied in a gas field, and the risk value and risk grade of a practical well are semi-quantitatively evaluated. The overall risk situation of the well is obtained. The research results provide important technical guidance for the safe production of gas well.</span>
文摘Objective To understand the occurrence and distribution of Campylobacter jejuni in chicken in China, assess its health risk to the Chinese population, and provide recommendations for effective risk control. Methods Data from the National Food Safety Risk Surveillance Network on Campylobacter jejuni between 2007 and 2010 and from published articles were analyzed. Eleven parameters were used based on the whole chicken preparation process and prevalence of Campylobocter jejuni for risk assessment by using the Ross-Sumner Method. Results The detection rates of Campylobacterjejuni in raw chicken were between 0.29% and 2.28% during 2007-2010 in China （more than 20 provinces）. The probability of illness caused by Campylobacter jejuni due to chicken consumption was around six out of one million consumers per day in urban areas and around one out of one million consumers per day in rural areas. Total predicted illnesses per year was about 736 000, accounting for 1.6‰ of the general population in urban areas and about 301 000, accounting for 0.37‰ of the total population in rural areas. The risk rankings of Campylobocterjejuni in chicken were 52 and 49 in urban and rural areas, respectively. Conclusion A high risk score for Campylobacterjejuni in chicken was obtained in China. This result may contribute to development of food safety management strategies. Key efforts should be made to control the risk of Campylobacterjejuni in chicken in China, especially in chick breeding and chicken preparation processes.
