联合EMD及小波阈值去噪在电成像测井数据中的应用

钻井过程中钻头震动井壁会形成较浅的孔洞与划痕,在电成像静态图中表现为麻点噪声或颜色相对较深的条、块状干扰,影响裂缝的识别和参数的提取。为了降低背景噪声的影响,将联合经验模态分解法(EMD)及小波阈值去噪方法应用到电成像测井的电导率曲线中。结果表明:背景噪声主要存在于电导率曲线的高频部分,把电导率数据EMD分解后,对得到的高频固有模态函数(IMF)分量进行小波阈值去噪可有效减少背景噪声,输出的FMI(地层微电阻率扫描成像)静态图中麻点噪声和条、块状干扰明显减少;由去噪电成像静态图计算得到的缝洞面孔率与岩心孔隙度有更好的线性关系,与常规资料孔隙度和人工拾取的裂缝面孔率具有一致性,说明基于EMD的小波阈值去噪方法在电成像测井数据中的应用是有效的。

Coalbody structure classification method based on dual-lateral and RXO crossplot analysis

According to the positive correlation of coal ash content and natural gamma, using a new coal core reposition method, which is ordered by global and local extreme, coal samples from medium-thickness seam are reasonably located. Inte- grated the data of coal macrostructure characteristics, coal petrography analysis and coal gas production test, it studies the rela- tionship between coalbody structure and amplitude variation of different well logging data, and the tectonic coal recognition method with well logging data in fresh-water mud invasion. The results show that： the anomalous response of natural gamma ray, neutron, density and apparent resistivity does not reflect the coalbody structure type. In fresh-water drilling mud invasion, using the crossplot technique of dual-lateral, RXO resistivity response and the coalbody structure can classify granulated coal accurately; the proposed method is of good practicability and high reliability.