Automatic pickup algorithm of shale bedding based on derivative characteristics of micro resistivity curve
Bedding is one of the most typical and important characteristics of clastic rocks,and its development density(bedding density)reflects the changes of sedimentary environment and sediment to a certain extent.Aiming at the identification of shale bedding using micro resistivity scanning logging,first,the logging response of the bedding is extracted by trend filtering.Secondly,the quantitative relationship between the bedding interface and the first and second derivative of the logging curve is established.In other words,the bedding interface usually corresponds to the"half amplitude point"of the logging curve,which is approximately represented by the extreme point of the first derivative or the zero point of the second derivative in mathematics.Then the zero search algorithm is used to automatically pick up the bedding interface and calculate the bedding density.The method in this paper is applied to the bedding evaluation of the shale gas reservoir in Longmaxi formation,south Sichuan,and the calculated results are consistent with the bedding fractures observed in the core.Meanwhile,the comparison with the organic carbon content shows that the bedding density of the"sweet spot"segment with better source rock quality shows an obvious decreasing trend,indicating the effectiveness and feasibility of the bedding parameter evaluation in the shale gas reservoir evaluation.
Micro resistivity scanning loggingTrend filteringSecond derivativeShale reservoirBedding density
万方数据
维普
