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特高含水后期,河道砂体内部夹层是影响层内剩余油分布的重要因素。针对特高含水后期密井网条件下不同类型的河道砂体,以萨尔图油田北二西区5口小井距密闭取心检查井为研究对象,采用统计和预测分析方法,对曲流河河道、辫状河河道、高弯曲分流河道、低弯曲分流河道和水下分流河道砂体内部夹层进行了定量描述,对夹层的岩性、厚度、分布部位及稳定性等特征进行了研究。结果表明,辫状河河道—曲流河河道—高弯曲分流河道—低弯曲分流河道—水下分流河道砂体内部夹层的岩性呈泥砾岩—粉砂质泥岩—泥质粉砂岩—泥岩的变化趋势,夹层厚度呈明显变薄趋势;不同类型河道砂体内部夹层厚度较小,厚度小于5 cm的夹层占总夹层数的65.5%;夹层的分布部位和倾角差异大,层内薄夹层多,测井资料无法识别的夹层占总夹层数的69.6%;辫状河河道砂体内部夹层的稳定性较好,曲流河河道砂体内部夹层稳定性最差。辫状河河道砂体剩余油主要受沉积韵律影响,曲流河河道砂体中的剩余油主要受侧积夹层控制,低弯曲分流河道发育水平稳定层理,削弱了油层内部流体因重力作用而导致的水淹程度差异,砂体内部水淹程度相对均匀,有利于驱油效率的提高。
In the late ultra-high water-cut period, the inter-channel interbed of channel sand bodies is an important factor that affects the remaining oil distribution in the strata. Aiming at the different types of channel sand bodies under the conditions of close well pattern in the late ultra-high water-cut period, taking five well-bore closed coring wells in the north two-western region of Salto Oilfield as the research object, the statistical and predictive methods were used to analyze the meandering river channels , Braided river channel, high-bending distributary channel, low-bend distributary channel and underwater distributary channel sand body were described quantitatively. The lithology, thickness, distribution location and stability of the interlayer were studied. The results show that the braided river channel - meandering river channel - high curved distributary channel - low curvature distributary channel - the lithology of interbeds inside the distributary channel sand body is conglomerate - silt mudstone - muddy siltstone - mudstone The thickness of interlayer is obviously thinning; the thickness of interlayer in different types of channel sand bodies is smaller, the thickness less than 5 cm accounts for 65.5% of the total number of layers; the distribution of sandstone and the angle of dip differ greatly, And the unrecognized mezzanine data account for 69.6% of the total number of sand layers. The stability of interlayer in braided river sand bodies is better, and the mezzanine stability in meandering river sand bodies is the worst. The remaining oil in the braided river channel sand body is mainly affected by the depositional rhythm. The remaining oil in the meandering river channel sand body is mainly controlled by the lateral mezzanine and the stable stratification of low-bending distributary channel development, which weakens the internal gravity of the oil layer due to gravity Resulting in the difference of water flooding degree, the water level inside the sand body is relatively uniform, which is propitious to the improvement of flooding efficiency.