胜坨油田三角洲前缘地层测井频谱分析及地质意义

以东营凹陷胜坨油田沙二段8砂组三角洲前缘地层为例,利用最大熵谱分析法和预测误差滤波分析法,揭示了三角洲前缘地层中的测井频谱特征及地质意义。研究表明,地球轨道周期是控制三角洲前缘地层旋回形成的重要因素,测井频谱特征表现为米氏旋回与非米氏旋回叠加。米氏旋回在三角洲前缘地层中占主导地位,主要存在于同一期次的沉积地层中,反映沉积环境相近或渐变,沉积连续性好。非米氏旋回对应的层段所占比例较小,主要存在于2期三角洲前缘地层的分界处,反映沉积不连续或沉积环境突变,可以作为沉积界面的解释依据。利用频谱趋势曲线,将胜坨油田沙二段8砂组三角洲前缘地层划分为2个完整的中期基准面旋回,合理揭示了地层的成因及沉积过程。

Log spectrum analysis and its geological significance on delta front formation of Shengtuo Oilfield

Taking the delta front formation of Es2s sands of Shengtuo Oilfield in Dongying Depression as an example, the maximum entropy spectrum analysis and predication error fiher analysis were utilized to describe the logging frequency spectrum features and reveal the geological significance. The study shows that the cycle sequence in the delta front formation is controlled by the earth orbit cycle, and the spectrum feature presents as the superimposition of Milankovitch cycle and non-Milankovitch cycle. The Milankovitch cycles are dominant in the delta front formation and are conserved mainly in equivalent layer, which reflect the similar or gradual- change depositional environments and continuous depositional process. The intervals corresponding with non-Milankovitch cycles occupy a small proportion, and they exited mainly in the strata between two-stage delta front formations, which reflec, t the discontinuous deposition and the abrupt change of depositional environment and can act as a criterion to distinguish the depositional interface. Based on the spectrum trend curve, the delta front reservoir of Es 2 8 sands in Shengtuo Oilfieht can be divided into two integral middle-term base level cycle, which revealed the genesis and sedimentary process of formation reasonably.