姬塬地区长81油层组砂体结构特征及对油藏的控制作用

作为姬塬地区主力开发层系的长8₁油层组，其砂体的交错叠置关系严重影响该地区油藏分布规律的认识。为了研究长8₁油层组砂体结构特征及其对油藏分布的控制作用，立足于长8₁油层组的砂体形成机理，综合沉积、测井等资料划分砂体结构类型，刻画砂体的横向交错和纵向叠置关系，进而厘清砂体结构对油藏分布的控制作用。研究结果表明:姬塬地区的砂体结构可划分为4种类型，分别为叠合箱型、齿化钟型、孤立箱型和孤立指状型，其中叠合箱型砂体含油性好，是油藏主要储集体；齿化钟型和孤立箱型砂体顶底含油性差，中部含油性好且均匀；孤立指状型砂体物性和含油性均较差。该地区的砂体结构与有利区分布具有显著关系，叠合箱型砂体发育地区多为Ⅰ类有利区。研究成果可为姬塬地区长8油藏的精细勘探开发提供依据和方向。 

Controlling effects of sand body structural characteristics on oil reservoirs of Chang 81 oil layer in Jiyuan area

As the main development strata in Jiyuan area, Chang 8₁ oil layer has a staggered superimposed relationship of sand bodies, which seriously affects the reservoir distribution in this area.The study on the structural characteristics of the sand bodies in Chang 8₁ oil layer and their control effects on reservoir distribution is carried out, which is beneficial to the continuous exploration and development in Jiyuan area. Based on the formation mechanism of sand bodies in Chang 8₁ oil layer, the sedimentary and logging data were combined to divide the structural types of sand bodies, and the relationship between transverse interlacing and longitudinal superposition of sand bodies was described. Further, the control effects of sand body structure on reservoir distribution were clarified. Results show that the sand body structure in Jiyuan area can be divided into four types, including superimposed box shape, toothed bell shape, isolated box shape and isolated finger shape. The superimposed-box-shape sand body has good oiliness and is the main reservoir body. The top and bottom of the toothed-bell-shape and isolated-box-shape sand body have poor oiliness, but the middle part of them has good and uniform oiliness. The isolated-finger-shape sand body's physical properties and oiliness are poorer. The sand body structure in this area is significantly related to the distribution of favorable reservoirs. Most of the superimposed-box-shape sand bodies are of type I favorable reservoir. The result can provide the basis and direction for delicate exploration and development of Chang 8 reservoir in Jiyuan area.