Analysis of the nutrient distribution features and affecting factors in the Jiulongjiang estuary

根据2009、2010年“丰水期“和“枯水期“四航次九龙江河口混合区的调查资料,且结合历史资料对营养盐含量及分布特征、周日变化特征进行了统计和相关分析,研究了九龙江流域营养盐输入海洋的变化过程,探讨九龙江河口营养盐伴随潮汐变化,以及河口混合过程中的生物地球化学行为。调查期间溶解无机氮、硅和磷含量的平面分布呈现出由径流冲淡水高值向河口外海端递减的变化趋势;在涨潮时,河口区感潮段高溶解无机氮、硅、磷营养盐的陆源冲淡水与低溶解无机氮、硅、磷营养盐外海水相遇,随着外海水的侵入,外海水的作用逐渐加强,在稀释混合过程中呈现出无机营养盐逐步降低的变化趋势,退潮时则相反;营养盐在这复杂的河口过程中往往表现出在水动力的作用下稀释混合是主要过程,无机氮和活性硅酸盐在河口稀释混合过程中呈现保守性特征,活性磷酸盐在河口转移(补充)过程的行为复杂化,呈现缓冲作用为主。Based on the historical data and the data from four surveys in the wet season and dry season of 2009 and 2010 in the Jiulongjiang estuary,the concentration and distribution of nutrient were discussed in the mixing process.Furthermore,the daily variation of nutrient concentration with the tide was also discussed.The results showed that:(1) the concentration of total dissolved inorganic nitrogen,silicate and phosphate all decreased gradually from the river runoff to seawater;(2) in high tide,in the mixing process of the runoff with high nutrient concentration and the seawater with low concentration of nutrient,the concentration of nutrient decreased due to seawater.On the contrary,during the ebb,the concentration of nutrient increased due to the runoff;(3) in the mixing process in Jiulongjiang estuary,nitrogen and silicate were both conservatively diluted,but phosphate was buffered because of the complicated transfer and complement of phosphate.国家海洋局公益性项目(200805064);国家海洋局第三海洋研究所基本科研业务费项目(海三科2009021);海三科200900

水驱气藏气井试井曲线特征及典型实例分析

针对水驱气藏的特点,建立了边水、底水驱气藏的不稳定渗流的物理模型。按正常温压、高温高压系统两种情况,分析了气、水两相流体高压物性对边、底水气藏试井曲线的影响,揭示了边水驱气藏试井曲线具有复合模型特征的原因;论述了底水气藏、边水气藏与封闭有界情形试井曲线特征的差异。最后用测试实例并结合生产动态说明了底水气井试井曲线特征以及进行早期识别水侵的方法

A balance equation of gas materials with recharge capacity and their performance prediction

传统的物质平衡方法将整个气藏当作一个容器,忽略了地层的非均质性以及渗流阻力,在使用二项式产能方程和物质平衡方程对非均质低渗透气藏进行早期动态预测时,指标总是偏向乐观。针对该问题,假设气藏被一低渗透条带分为两个相互联系的相对均质区块,根据质量守恒原理,利用半透壁模型建立了具有补给的非均质气藏物质平衡方程及动态预测理论模型。该模型不但考虑了气田区域性非均质变化因素以及流动阻力,使物质平衡模型更加接近实际,又可简单快捷地预测气井动态变化趋势,揭示了两区内压力、产量随时间变化规律。实例计算结果表明:该模型能够改善早期动态预测结果,各项指标接近生产实际

Dynamic production performance prediction and decline laws of rectangular gas reservoirs

单井的生产动态预测通常分为定产降压和定压降产两个阶段,采用二项式产能方程和物质平衡方程对矩形低渗透气藏进行早期动态预测时,指标总是倾向乐观。针对该问题,将井位于矩形边界某一位置处的压力解与物质平衡方程相结合来预测定产降压阶段的井底流压、地层平均压力的变化,避开了产能方程的时效性问题;根据物质平衡方程和产能方程,建立了定压生产条件下的递减公式,并采用Wattenbarger定压形状因子进行定压降产阶段的动态预测,揭示了压力、产量随时间变化规律。实例计算结果表明:新建模型能够改善早期动态预测结果,各项指标接近生产实际。研究成果对于类似气藏合理有效开发方案的制订具有指导意义

A well test model for composite reservoir with resistance force on interface

Tazhong No.1 gas field is a typical vug-fractured carbonate gas condensate reservoir with the characteristics of high heterogeneity and complex geological and dynamics. A physical and effective hole-diameter mathematical model for well test in the composite reservoir is established, which considers the resistance force on interface. Specifically, the following factors are involved, including wellbore storage and skin factor of inner boundary, fracture open of interface, and infinite boundary of outer boundary. Moreover, the exact solution of wellbore pressure is obtained in terms of ordinary Bessel functions in the Laplace space. The numerical computation of the solution is obtained by using the Stehfest numerical inversion method, and the behavior of the system is studied as a function of various interface parameters. Results show that the composite radius controls the time of the interface performance. The larger the composite radius, the later the interface performance begins. In addition, the condition of open fracture has a heavy impact on the transitional zone performance. Resistance force on the interface disguises the influence of the condition of the open fracture, which is more apparent with larger resistance force. Comparisons with the regular well test model shows that the new model can improve the data utilization, reduce multiple solutions of well test analysis and increase the accuracy on the identification of formation parameters and evaluation stimulation. The method is useful for the reservoir dynamic description

Characteristics of well tests in the carbonate reservoirs of the eastern Tazhong-1 Gas Field,Tarim Basin

塔里木盆地塔中Ⅰ号气田东部试验区储层高温高压,流体性质和流动机理复杂;试井曲线具有多样性、复杂性及多解性的特点,试井分析面临巨大的挑战。为此,根据研究区地质特点及有关资料录取情况,采用现代试井分析方法与生产动态分析相结合的非均质气藏动态描述综合技术,将储层划分为视均质、双重孔隙、复合模型以及裂缝、裂缝孔洞模型等5种类型进行试井分析。结果表明:该区储层非均质性较强,平面连通性差;试井特征与稳产能力有着紧密的联系,对不同类型的井,应制订相应的开发技术对策

基于二阶B样条的ILK流量反褶积算法改进及应用

受ILK压力反褶积算法压力计算精度高的启发,基于一个等价的褶积积分方程,改用流量数据代替原算法所采用的累积流量数据进行反褶积计算,并给出了反褶积算法的快速求解方法:利用褶积积分的数学性质,采用按照压力降落段进行分段积分的方法,快速地解析求解反褶积计算过程中的敏感性矩阵;同时利用二分法快速查找每组流量数据点所属的压力降落段,进一步提高了计算效率。通过理论算例和实际算例的测试分析表明,改进后的ILK流量反褶积算法具有更高的计算精度,尤其使初始和后期阶段的流量数据精度有了较大提高,实际算例的计算结果更加符合单位井底压力降下的流量递减变化规律。与原算法相比,改进算法在产量递减分析时可以获得更长的表征拟稳态流的特征直线段,显著提高了数据的拟合效果,也具备较高的计算速度、稳定性及实用性。因此,将该反褶积算法应用于产量递减分析不仅可以有效降低数据误差影响的敏感性,还可以获得更多的数据信息量,提高数据的拟合效果,降低解释结果的不确定性