新安边地区长7主力油藏辨识

Identification of Chang 7 main reservoir in Xin′anbian area

鄂尔多斯盆地三叠系延长组长7致密油储集层致密,孔隙结构复杂,孔隙度小,渗透率低,储集层微裂缝发育,盆地新安边地区长7油藏受沉积环境控制,砂体横向变化快,纵向隔夹层发育,主力贡献层识别难度大。综合地质研究认为,长7段页岩油具有砂泥储层大面积分布、储层致密但流体可动性较好、含油饱和度高、油质轻、气油比较高、埋藏较浅、资源量大等特点。针对新安边地区长7致密油储层,通过综合应用数理统计法和岩心观察、常规测井、核磁测井识别法,建立了主力贡献层纵向识别标准,以目前勘探成果为依据,多参数综合评价确定有利区、次有利区和不利区的阈值范围。评价结果具有很好的一致性,解决了储层单因素评价过程中出现的评价结果相互交叉、不唯一的问题,有利于对致密油储层进行合理评价。应用该结果指导水平井轨迹设计优化,取得了较好的应用效果。

Chang 7 tight oil reservoir in Yanchang Formation of Triassic in Ordos Basin is dense,with complex pore structure,small porosity,low permeability and developed microfractures.Chang7 reservoir in Xin′anbian area of Ordos Basin is controlled by sedimentary environment,with rapid horizontal change of sand body and development of vertical interlayer,so it is difficult to identify the main contributing layer.Comprehensive geological research shows that shale oil in Chang7 member has the characteristics of large area distribution of sand mud reservoir,compact reservoir but good fluid mobility,high oil saturation,light oil quality,high gas oil ratio,shallow burial and large amount of resources.Aiming at Chang7 tight oil reservoir in Xin′anbian area,through the comprehensive application of mathematical statistics,core observation,conventional logging and nuclear magnetic logging identification methods,the vertical identification standard of main contributing layer is established.Based on the current exploration results,the threshold range of favorable area,secondary favorable area and unfavorable area is determined by multi parameter comprehensive evaluation.The evaluation results have good consistency,which solves the problem that the evaluation results are cross and not unique in the process of reservoir single factor evaluation,and it is conducive to the correct and reasonable evaluation of tight oil reservoirs.The application of this understanding to guide the trajectory design optimization of horizontal wells has achieved good application results.