Determination of the sequence boundaries of the Pliocene formations (Cheleken and Aghchagyl) of Gorgan plain by cyclolog software and gamma-ray deviation method

The use of borehole logs in no-core wells to identify complications related to rock strata has always been of interest to geologists. Identifying the key levels of sequence stratification is one of the important parts of the geological characterization of hydrocarbon reservoirs. In this study, the effectiveness of the Dynamic-Integrated Prediction Error Filter Analysis (D-INPEFA) of gamma log dynamic error prediction filter integrated analysis chart in identifying and separating sequences and key stratal surfaces in Sofikam-1 key well in Gorgan-Gonbad Kavus plain for the Cheleken and Aghchagyl formations sequence has been evaluated. gamma Log analysis, especially (D-INPEFA), led to identifying stratal surfaces in Cheleken and Aghchgyl sequences. Fifteen sequence boundaries, including eight negative boundaries (nb) and seven positive boundaries (pb), were identified in the Sofikam-1 well using cumulative error prediction filter analysis. The sequence levels, including formation boundary, sequence boundary, and maximum flooding surface, were identified. According to the identified boundaries four third order sequences, were determined in Sofikam-1 well. Based on this, according to the general trend of the gamma diagram, a regressive trend was determined for the Cheleken Formation and a progressive trend for the Aghchagyl Formation.