Ginseng is a perennial herb with a long growth cycle and is known to easily accumulate pesticides during its growth process, seriously threatening people's health. Therefore, to ensure safe consumption, it is necessary to detect and monitor pesticide residues in ginseng. In this study, a novel analysis method was established for simultaneous determination of 31 pesticides in ginseng by high-performance liquid chromatography-mass spectrometry. Ginseng samples were extracted using acetonitrile, cleaned up by primary secondary amine (PSA) solid-phase extraction column eluted with acetonitrile-toluene, and then detected in multiple reaction mode (MRM). The calibration curves of target compounds were linear in the range of 0.005–1.0 mg/L, with correlation coefficients greater than 0.9921. The limits of detection of all the pesticides in ginseng were between 4.4×10−5 and 1.6 × 10−2 mg/kg. For fresh ginseng, the average recoveries ranged from 72.1 to 111.6%, and the relative standard deviations were 1.3–12.2%. For dry ginseng, the average recoveries were 74.3–108.3%, and the relative standard deviations were 0.9–14.9%. The residual concentrations of some pesticides in real samples were greater than the maximum residue limit (MRL) for European Union (EU). The method established here is rapid and simple with high sensitivity and good reproducibility, which is sensitive in the residue analysis of many pesticides in ginseng.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIndustry experience has shown that frac pack completions can provide effective production stimulation and reliable sand control for unconsolidated sand reservoirs. One of the more rewarding areas of opportunity is in the completion of longer and more complex intervals that can be stimulated with a single frac pack, high-rate water-pack (HRWP) or EX-Tension Pac SM Service treatment. One of the major considerations in planning the \well completions in the BZ-25-1 field was design efficiency. To complete each individually zone independently with a Stack Pack completion would have been very time consuming. This paper presents the results from installing frac-pack and HRWP treatments through a single-trip, multiple-zone (STMZ) completion system in the offshore Bohai field in China. Using the 9 5/8 × 4.75-in. ID single-trip gravel pack tools, operators have performed frac packing and HRWP treatments on 58 wells, on three platforms, during 2003 and 2005 with an average of 3 to 5 zones per well, spending an average of less than 3 days to complete each well. This paper presents the selection process for the completion technique used to achieve high production efficiency and initial performance of the field. It provides guidelines and results associated with frac packing and demonstrates the importance of selecting completion techniques that will provide high-efficiency production.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIndustry experience has shown that frac pack completions can provide effective production stimulation and reliable sand control for unconsolidated sand reservoirs. One of the more rewarding areas of opportunity is in the completion of longer and more complex intervals that can be stimulated with a single frac pack, high-rate water-pack (HRWP) or EX-Tension Pac SM Service treatment. One of the major considerations in planning the \well completions in the BZ-25-1 field was design efficiency. To complete each individually zone independently with a Stack Pack completion would have been very time consuming. This paper presents the results from installing frac-pack and HRWP treatments through a single-trip, multiple-zone (STMZ) completion system in the offshore Bohai field in China. Using the 9 5/8 × 4.75-in. ID single-trip gravel pack tools, operators have performed frac packing and HRWP treatments on 58 wells, on three platforms, during 2003 and 2005 with an average of 3 to 5 zones per well, spending an average of less than 3 days to complete each well. This paper presents the selection process for the completion technique used to achieve high production efficiency and initial performance of the field. It provides guidelines and results associated with frac packing and demonstrates the importance of selecting completion techniques that will provide high-efficiency production.

This paper summarizes the three big challenges in the development of the oilfields in Bohai Bay: most of the reserve is heavy oil; formation is unconsolidated and lower productivity after sand control operation. Through years of research and improvement, based on serious analysis of reservoir characters and oil production performance, method of drilling and completion and production management, traditional distribution of the mesh of directional well and conventional gravel pack sand control method are changed and an alternation of sand management multilateral technology is adopted to enhance the production and oil recovery with three technology characters: one is the control of the drop of production pressure under the condition of sand management, until this technology is applied in Bohai Bay, remarkable achievement is made in the field of enhance the production and oil recovery for the development of new oil field and the reboot of the older oil field, which has been one of the key technologies to apply to a large scale and continuously improve. It has been exerting a lot of pressure and positive influence on the technology of production, drilling and completion technology, and further performance of the EOR. Key words: Bohai Bay Oilfield development Drilling and completion technology multilateral well Sand management Enhanced oil recovery Introduction Over fourth year's exploration, Numbers of oil fields has been developed in Bohai field, which has been a mainly base of oil and gas production for CNOOC. However, during the development of the Bohai oil field, the mainly characters is the most of reservoirs distribute at upper series with heavy oil and higher viscosity. The development of the old field faces the serious challenges because of the higher investment and higher operational risk. On stepping into the middle of eighties, as a delegation of Northern Cheng Oilfield, we initiate to probe the development of the offshore oilfields. In nineties, the largest oil fields at that time BHSZ36–1, operated by us, was developed by applying for technologies such as the branch well and cased hole gravel packing [1], [2]. Great achievements have been made on the mode of developing heavy oil and related drilling and completion technologies, also accumulated a wealth of experience for the development of the heavy oil in Bohai Bay. Later on, The Optimized Drilling Technology was conducted in Bohai bay and applied in the BHSZ36–1-J region successfully [3], [4], [5]. However, New challenges such as low productivity for individual, higher cost of completion, formation damage, economical benefit marginal etc., has encountered during the development of the oilfield, therefore, How to improve the technologic level further, accelerate the development of the marginal oilfield and reduce the operational cost, enhance the well productivity has been a badly in need of being resolved. Recently, lateral well and fish-born wellborn technology was taken into the drilling of Bohai bay, while sand management technology was taken into the completion operation. Great progress has made during the development of new oilfield and positive and valuable attempts have been conducted on the heavy oil development and EOR with drilling technologies.

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