鄂尔多斯盆地延长组长7段致密油源储配置关系测井评价

Source-reservoir configuration of logging evaluation for tight oil in Chang 7member,Yanchang formation,Ordos basin

源储配置关系是致密油评价的核心组成部分.以鄂尔多斯盆地延长组长7段的岩心、测井资料为基础,经岩—电关系分析,优选深感应电阻率（RILD）与声波时差（AC）测井参数曲线重叠图法来识别烃源岩,并结合地球化学参数进行烃源岩品质评价;同时,开展砂体结构特征研究,并在单井、连井剖面中综合分析烃源岩品质、砂体结构特征、源储配置关系及含油性.研究表明：1）延长组长7段烃源岩发育段在深感应电阻率（RILD）与声波时差（AC）测井曲线重叠图上存在明显幅度差,累计厚度一般5~70 m,分布面积达10×104km;岩心分析及测井模型计算TOC值一般2%~20%,平均11.6%,TOC在平面上分布具较强非均质性;基于测试分析数据和实际生产需求,把鄂尔多斯盆地长7段泥页岩分为4类,优质烃源岩：TOC〉10%,中等烃源岩：6%〈TOC〈10%,差烃源岩：2%〈TOC〈6%,非烃源岩：TOC〈2%.2）影响鄂尔多斯盆地长7致密油富集程度的关键因素是烃源岩有机碳含量,其次是砂体结构,以及砂体与烃源岩之间的距离.一般在优质和中等烃源岩发育区,紧邻烃源岩的块状砂体的每米日产油指数（PI）一般大于2.0 t/m·d,远离优质或中等烃源岩的块状砂体PI一般为1.5t/m·d;不论层状砂体与烃源岩的距离远近,PI一般均为1.0t/m·d.差烃源岩发育区,紧邻或远离烃源岩发育区的块状砂体、层状砂体一般均为差油层或干层.

Source-reservoir configuration is an important part of tight oil evaluation. In this study, based on well logging and core data, we analyzed geologic information carried by various well logging data and used multiple parameters such as Deep Induction Resistivity of induction log （RILD） and Acoustic Transit Time （AC）, together with geochemical parameters, to identify and evaluate source rocks in Chang 7 member, Yanchang Formation, Ordos Basin. We studied the sand bodies and evaluated their oiliness on the basis of a comprehensive analysis on source rock quality, sand body structure, and source-reservoir configuration. The study shows： first, at the section that the Deep Induction Resistivity and Acoustic Transit Time logging curve overlaps, there is obvious separation in source rocks in Chang 7 member, where the thickness varies from 5m to 70 m, with an area of up to 10 x 104 km2. TOC values are between 2% and 20% , with an average of 11.6%. The TOC content of source rocks is horizontally anisotropic. According to the testing data and actual production demand, the source rock characteristics in Chang 7 member can be summarized as the following： high quality source rocks, TOC 〉 10% ; medium source rocks,6% 〈 TOC 〈 10% ; poor source rocks, 2% 〈 TOC 〈 6%; non-hydrocarbon source rocks, TOC 〈 2%. Second, it is indicated that the TOC content of source rocks played a key role in controlling tight oil enrichment, then come to sand body and the distance between sand body and source rocks. In the high quality and medium source rocks development zone, the well testing and oil producing （PI） index of massive sand body are more than 2.0 t/m · d. that of the bedded sand body are about 1.0 t/m · d. the index of massive sand body are in general 1.5 t/m · d in the regions further away from the high quality and medium source rock development zone. In poor source rocks development zones, the two kinds of sand bodies usually are poor oil layers or dry layers.