临兴地区下石盒子组盒8段层序地层精细研究

Detailed study of sequence-stratigraphic of He 8 Members of Lower Shihezi Formation in Linxing Area

目前利用单一的常规测井曲线不能清晰地识别出地层的叠置序列与沉积旋回特征,在砂层组划分与对比过程中存在较强的多解性。针对这些问题,在最大熵谱分析(MESA)的基础上进行预测误差滤波分析(PEFA),进一步对PEFA曲线进行积分处理得到综合预测误差滤波分析(INPEFA)趋势线,该方法能够提取出所隐藏测井曲线中反映地层叠置序列及沉积旋回特征的频谱趋势线,通过分析其变化特征及其所代表的地质意义,厘定历史时期的沉积演变旋回过程。利用INPEFA方法对临兴地区盒8段自然伽马曲线进行处理,得到自然伽马曲线的频谱趋势线,并反复进行连井剖面对比,进而将盒8段地层划分为3个中期基准面旋回,在此基础上将其砂体划分为5套砂层组,并分别绘制了各砂层组的平面厚度等值线图。

At present,multiple solutions are exist in the division and correlation of sand formations when using of a single conventional logging curve. As a result,the stratigraphic sequence and sedimentary cycle characteristics of the strata can not be clearly identified. As a solution to the above problem,the Prediction Error Filter Analysis(PEFA) was carried out on the basis of Maximum Entropy Spectrum Analysis(MESA). And the Integral Prediction Error Filter Analysis(INPEFA) trend line was obtained by the further integration of the PEFA curve. This method can extract the spectrum trend line which reflects the stratigraphic stacking sequence and the sedimentary cycle characteristics that are hidden in the logging curve. The process of sedimentary evolution of the historical period was established through analyzing the variation characteristics and the geological significance of the spectrum trend lines. In this paper,the INPEFA method was used to analyze the natural gamma ray curve of He 8 formation in Linxing Area and then the spectrum trend line is obtained. By contrasting the well connection profile in detail,the He 8 formation was divided into three mid-term base-level cycles. And based on that,the sand body was divided into five sand groups and the thickness contour map was drawn respectively.