利用声波时差划分地层在周口坳陷的应用

Application of Interval Transit Time to Formation Zonation in Zhoukou Sag

通常依据岩性和电性特征进行地层划分,当二者在地层划分存在分歧时,常以主观偏重于某一因素而确定地层分界线,有失客观。利用声波时差,结合自然电位,在储集层段自上而下读取声波时差值(Δt),并以地层深度(H)为横坐标,以对数为纵坐标,作散点图;按散点图特征进行线性回归,在回归线斜率发生变化之处,即是地层层位发生变化,以此确定地层分界线,进行地层划分。该方法具体应用在周口坳陷的FY区块地层划分上,解决了地层划分上的分歧,得到较客观的结果。

Formation classification usually relies on lithological or electrical characteristics in geology, which makes mistake when there is difference between the results of the two characteristics. The new method of interval transit time to classify formation may solve the problem. The value Δt of reservoir displayed by SP curves is read from top to bottom; and the dispersing or distributing points of formation depth(H) versus its corresponding value Δt are plotted with the depth H as abscissa and common logarithm as ordinate. These points are the changes of regressed curves declination rate of the dispersing points , thus indicating that the intervals have changed . So , the formation is zoned based on these changes. This new method has been successfully used in formation zonation of Zhoukou sag .