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Injection profile surveillance using impulse oxygen activation logging based on optimization theory
Journal of Petroleum Science and Engineering ( IF 5.168 ) Pub Date : 2020-08-01 , DOI: 10.1016/j.petrol.2020.107701
Guofeng Yang , Xiangjun Liu , Jiacai Dai , Meng Chen , Xiaolong Wu

Impulse oxygen activation logging based on pulsed neutron technique is a widely used method to monitor the injection profile. The instrument utilizes a D-T generator to activate the oxygen nuclei in the borehole and the secondary gamma-rays are measured by the scintillation detector. According to the timing principle, it can detect the water flow and provide a quantitative measure of flow using a serious of station measurements. The traditional interpretation method uses the travel time of the activated water and the known source-to-detector spacing to estimate the flow velocity, which is not suitable for complex completions, due to the superposition of the signals from the tubing and annulus streams. In this paper, an optimization method is proposed to quantify the injection profile based on the physical principle of impulse oxygen activation measurement. The theoretical model of the dependence of the spectral count rate on time is established by numerical simulation based on the detector response function and the oxygen activation rate distribution. The theoretical model is a non-linear model, which describes the detector response to the flowing activated water. Then, the objective function for determining the flow velocities is constructed by minimizing the error between the measured spectrum and the predicted spectrum. A kind of evolutionary computing algorithm is used to search the optimal solution of the objective function to directly extract the flow velocities from the spectrum, which avoids the calculation of the travel times. The field example shows the unique advantage of the method in separating the flows in different spaces and the interpretation result proves the proposed optimization method can improve the precision of quantitative injection profile surveillance.



中文翻译:

基于优化理论的脉冲氧活化测井注气剖面监测

基于脉冲中子技术的脉冲氧活化测井是监测注入剖面的一种广泛使用的方法。该仪器利用DT发生器激活井眼中的氧核,并通过闪烁检测器测量二次伽马射线。根据计时原理,它可以检测水流,并通过大量的站点测量来提供水流的定量测量。传统的解释方法使用活化水的传播时间和已知的源到检测器间距来估计流速,由于来自管道和环流的信号叠加,因此不适合复杂完井。在本文中,提出了一种基于脉冲氧活化测量的物理原理来量化喷射曲线的优化方法。通过基于检测器响应函数和氧气活化速率分布的数值模拟,建立了光谱计数速率对时间的依赖性的理论模型。理论模型是非线性模型,它描述了检测器对流动的活化水的响应。然后,通过最小化测量光谱和预测光谱之间的误差来构造用于确定流速的目标函数。一种进化计算算法用于搜索目标函数的最优解,直接从频谱中提取流速,从而避免了行程时间的计算。

更新日期:2020-08-06
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