一种利用霍尔导数曲线反求地层参数的新方法

A New Method for Calculation of Formation Parameters by Hall Derivative Curve

改进霍尔曲线法是通过导数曲线与积分曲线的相对位置定性识别地层是否产生大孔道。由于导数曲线公式中含有与工作制度有关的参数,而实际生产中工作制度经常改变,这与改进霍尔曲线法采用的理想模型进行计算有所不同,通过实际生产数据绘制出的导数曲线特征与改进霍尔曲线法也有差异,因此为了避免工作制度对曲线产生的影响并能够定量识别孔道特征,将某区块生产数据计算出的导数数值解代入到解析解公式中,再利用提出的修正系数对与工作制度有关的参数相进行修正,得到修正系数为1.2。把渗透率作为未知数,将全区水井投产初期数据计算出的导数数值解代入到解析解公式中,将计算出的各井渗透率与实际水井地层渗透率相比较,误差小于8%的井占总井数的91.4%,验证本方法合理有效。取其中一口水井计算投产初期渗透率为16.41mD,预测长期注水后地层渗透率为36.77mD,发现长期注水后地层渗透率变大,说明产生优势渗流通道,与绘制的改进霍尔曲线规律一致。

The modified hall curve method is qualitative identification of stratum pore passage characteristics from relative relationship between derivative curve and integral curve.The analytic solution formula contains the work system-related parameters,however,the work system often changes in practice production,therefore,this formula is slightly different from the ideal model used in the modified hall curve method.The derivative numerical solution curve and analytic solution curve plotted according the actual production data are different from the modified hall curve.In order to avoid the effect of work system on analytic solution and quantitatively identify pore passage characteristics,the derivative numerical solution calculated from the production data of one block was taken into the analytic solution formula,and the proposed correction efficient was used to modify the parameters related to the working system,and the correction efficient was 1.2.The permeability was used as an unknown value,and the derivative numerical solution calculated from the initial production data of the block was taken to the analytic solution formula.The comparison of the calculated permeability and actual formation permeability of the wells showed that the number of wells with the error below 8%accounted for 91.4% of total number of wells,verifying that this method was rational and effective.For one well,the permeability was 16.41 mD at initial production stage,and the predicted formation permeability was 36.77 mD after long-term water injection.It was found that an increase in formation permeability after long-term water injection showed that preferential migration passages were produced,which was consistent with the plotted modified Hall curve.