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In most parts of the world, open hole logging with con-ventional gamma density tool remains the only option available, which is, though, not practical under complex well conditions when it is difficult to obtain formation parameters and control the operational risks. Therefore, the application of through-casing density logging is es-sential. However, through-casing gamma density meas-urement could be challenging due to gamma’s weak pen-etrating power. To better overcome these challenges, a new four-detector gamma density tool is designed and presented in this work together with a novel interpreta-tion algorithm for through-casing density measurements. In order to identify the relationship between the four de-tectors, a significant amount of Monte Carlo models is constructed and executed to quantitatively evaluate the response of tool under various environmental conditions such as lithology, fluid, salinity, casing and cement. It is proven through open-hole benchmarking and extensive modelling that the four-detector design is capable to pro-vide sufficient information for removal of diverse envi-ronmental effects via an inversion algorithm developed by obtaining a formula that correlates the four-detector responses. This algorithm is validated against actual log-ging data and show a better though-casing evaluation than when using three or two detectors. In this work a case story using the four-detector tool to obtain through-casing formation density and using the algorithm mentioned above for correction is presented. The final results are analyzed and compared against open hole measurements, a very good consistency is achieved which demonstrates the correctness of the inversion al-gorithm.

This paper presents the evolution of completion sand control designs for the Peng Lai field in Bohai Bay, offshore China. A range of sand control designs from open hole gravel packs to open hole standalone screens to cased hole high rate water packs and cased hole frac-packs have been tried over time. Evaluation of these various designs indicates that single-trip multi-zone cased hole frac-pack designs provide the most effective method for developing the thick, low net-to-gross, unconsolidated sandstone reservoirs in this waterflood field. The paper describes the completion design and evaluation process used in the field and shows how field challenges led to innovative frac-pack downhole equipment designs. This paper highlights completion practices and results from a range of well types used to develop the large Peng Lai field, offshore China. Development challenges and productivity and reliability results for alternative completion designs are discussed on the basis of field performance. The resulting preferred design, consisting of cased hole frac-packs using large-bore and small-bore single-trip multi-zone equipment are then discussed in further detail with emphasis on development of an innovative, fit-for-purpose, small-bore design. The installation challenges, solutions and successes experienced during the design and installation process and the actual performance and benefits of the new system are also discussed in this paper. Over the course of Peng Lai field development, a range of alternative completion sand control designs have been tried and evaluated. Cased hole frac-packs provide the most effective completion method for the thick, low net-to-gross, sandstone reservoirs. To enable effective completions in sidetracked wells, a 7" single-trip multi-zone frac pack tool has been developed. This small-bore system has been used to complete 13 wells with 67 zones in the field to date, saving over 43 rig days and $8MM. This paper presents reliability and productivity comparisons for a range of alternative completion sand control designs in a single, large field environment. A new 7" single-trip, fit-for-purpose design has been developed for the field and successfully implemented in multiple well campaigns. Installation time data and cost savings are provided.

Using Fourier transform near-infrared (FTNIR) transmission spectroscopy and moving window partial least squares (MWPLS) method, the quantitative analysis models for brix degree of sugarcane clarified juice were established, and spectral analytical waveband was optimized. All samples were differently divided into the calibration set and the prediction set for 50 times, and the MWPLS models with changeable parameters were established for each division respectively, for the same parameters combination, then RMSEPs for all the 50 divisions were averaged. Based on the average data, the optimal model was selected, with the waveband, number of adopted wave numbers, PLS factor, RMSEP and RRMSEP were 7367-7324cm-1, 12, 8, 0.44oBx and 2.8%, respectively. The result shows the above prediction effect was obviously better than the one of PLS model on the whole spectroscopy collecting region, and the optimal model using only 12 wave number points was simple and stable, providing valuable reference for designing minitype special NIR spectral instruments.