致密砂岩裂缝填充识别及其测井响应特征——以鄂尔多斯盆地镇泾油田延长组为例

鄂尔多斯盆地镇泾油田延长组发育致密砂岩裂缝，准确识别裂缝的填充程度有助于更好地评价和开发致密砂岩储层。运用延长组的岩心资料、成像测井资料和常规测井资料，统计裂缝的产状、填充矿物和填充情况，确定研究区裂缝主要岩性为细砂岩和粉砂岩，主要填充物为方解石，通过交会图和正态分布，总结了有填充裂缝和未填充裂缝的测井响应特征，对比了有填充裂缝和未填充裂缝的测井响应差异，选取裂缝敏感的测井参数，构建曲线变化幅度参数和曲线变化率参数，进而构建裂缝有未填充的综合指数识别方法。结果显示，感应测井对裂缝有填充和未填充响应有明显差异，孔隙度测井对裂缝有填充和未填充有一定的响应差异，岩性测井响应差异最不明显。将响应特征和识别方法应用于研究区2口井，对裂缝有未填充的综合识别率达76%。结果表明该响应特征和识别方法可为致密砂岩裂缝填充评价提供新思路，完善裂缝致密砂岩储层的评价方法。

Fracture filling identification and logging response characteristics of tight sandstone -a case study of Yanchang Formation in Zhenjing oilfield, Ordos Basin

The presence or absence of mineral fill in fractures has an important influence on the evaluation and development of tight sandstone reservoirs, and the accurate identification of fracture fill can help to better evaluate and develop tight sandstone reservoirs. The core observation and imaging log analysis were used to summarize the fracture production, filling minerals and filling degree; the fracture-sensitive log parameters were selected for the calcite-filled fractures mainly developed in the fine sandstone and siltstone in the study area, and the log response characteristics of filled and unfilled fractures were summarized by the rendezvous plot analysis and normal distribution analysis, and the log response differences between filled and unfilled fractures were compared. The response differences between the logs with and without filled fractures were compared. The results show that there is a significant difference between the response of induction logs to fractured and unfilled fractures, a certain difference between the response of porosity log series to fractured and unfilled fractures, and the least significant difference between the response of lithology log series. By extracting the fracture sensitivity parameters, the curve change amplitude parameter (FIA) and curve change rate parameter (FIR) are constructed, and then the integrated index (FFA) identification method of fracture with unfilled is constructed. The response characteristics and identification method were applied to two wells in the study area, and the results showed that the method achieved a 76% comprehensive identification rate of fracture with unfilled fractures. The response characteristics and identification method can provide new ideas for fracture filling evaluation of dense sandstone and improve the evaluation method of fractured dense sandstone reservoirs.