Natural Gas Compressibility Factor Correlation Evaluation for Niger Delta Gas Fields
Natural Gas Compressibility Factor Correlation Evaluation for Niger Delta Gas Fields
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尼日尔三角洲气田天然气压缩系数相关性评价
DOI：
10.9790/1676-0640110
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发表时间：
2013
期刊：
影响因子：
--
通讯作者：
C. Ubani
中科院分区：
文献类型：
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作者：
J. Obuba;S. S. Ikiesnkimama;C. Ubani
天然气压缩系数(Z)是天然气工业生产和输送的关键因素。本研究提出了尼日尔三角洲气田天然气压缩系数的新关联式。首先，天然气属性数据库是从尼日尔三角洲气田的二十二(22)个实验室气体PVT报告中开发的。其次，根据已开发的数据库(包括22个气藏和223个数据集)，对现有的天然气压缩系数对比进行了评价。利用建立的新关联式计算了干气、溶解气、富CO2气和富凝析气藏四种天然气成藏体系的z因子，并与已有的关联式进行了比较。与评价的相关系数相比，改进的校正结果显示出更好的统计排序、良好的图形趋势和最好的交会图奇偶线。结果表明，新建立的关联式的标准偏差和绝对误差最小，干气分别为1.461%和1.669%，溶液分别为6.661%和1.674%，富二氧化碳分别为7.758%和6.660%，富凝析气藏分别为7.668%和6.661%。新关联式的相关系数也很高，干气为93.39%，溶解气为89.24%，富CO2为83.56%，富凝析气藏为83.34%。此外，建议的新模型保持了良好的图形趋势，有四个z因素与之匹配：实验、估计(Standing-Katz)和匹配时的最佳评估相关性。与评估的相关性相比，交叉图的奇偶线表现非常好。由此可以得出结论：新发展的关联式和Papay关联式是计算尼日尔三角洲气田天然压缩系数最合适的关联式。Carr，Kobayashi和Burrow(1954)和Wichert-Aziz(1972)的修正因子法被用来修正非碳氢化合物的存在。但是，对PVT行为进行实验室分析的主要挫折有时是昂贵和耗时的。用于预测气体压缩系数的关联式比状态方程更容易、更快捷，而且总能节省成本。
Natural gas compressibility factor (Z) is key factor in gas industry for natural gas production and transportation. This research presents a new natural gas compressibility factor correlation for Niger Delta gas fields. First, gas properties databank was developed from twenty-two (22) laboratory Gas PVT Reports from Niger Delta gas fields. Secondly, the existing natural gas compressibility factor correlations were evaluated against the developed database (comprising 22 gas reservoirs and 223 data sets). The developed new correlation was used to compute the z-factors for the four natural gas reservoir system of dry gas, solution gas, rich CO2 gas and rich condensate gas reservoirs, and the results were compared with some exiting correlations. The performances of the developed correction indicated better statistical ranking, good graph trends and best crossplots parity line when compared with correlations evaluated. From the results the new developed correlation has the least standard error and absolute error of (stdEr) of 1.461% and 1.669% for dry gas; 6.661% and 1.674% for solution; 7.758% and 6.660% for rich CO2 and 7.668% and 6.661 % for rich condensate gas reservoirs. The new correlation also show high correlation coefficient of: 93.39%, for dry gas; 89.24% for solution gas; 83.56% for rich CO2 and 83.34% for rich Condensate gas reservoirs. Also the proposed new model maintained good graphical trends for four z-factors matched it: experimental, estimated (Standing - Katz) and the best evaluated correlation when matched. Very good crossplots parity line performance when compared with the evaluated correlations. It could then be concluded that the new developed correlation and that of Papay correlation are most appropriate correlations for calculating natural compressibility for Niger Delta gas fields. Carr, Kobayashi, and Burrows (1954) and Wichert-Aziz (1972), correction factor methods; were applied to correct the presence of non-hydrocarbons. But the major setbacks on laboratory analyses for PVT behavior are sometimes expensive and time consuming. Correlations, which are used to predict gas compressibility factor, are much easier and faster than equations of state, invariably save cost.