岩相单元是比小层更细、更能体现油藏地质特征的单油砂体。通过对岩相单元的细分与对比,可以满足油田开发中后期挖掘剩余油潜力的需要。以克拉玛依油田五2西克下组为例,遵循等时对比的原则,利用电测、岩心资料,以标准井为基础,作连井拉平沉积剖面图,从标志层、沉积旋回、沉积微相、砂体(油层)连通关系等方面进行对比,完成了区块的对比及统层。认为五2西克下组S7层属扇三角洲沉积,主力油层为S47;该层北部砂体厚度大,分布面积较广,连通性好,向南向西则逐渐变薄,面积变小,连通性变差,横向变化大,分布零散。

Lithofacies unit is the single oil sandbody which is more finer than microlayers, which mostly reflects geological characteristic of oil reservoir. Subdivision and contrast are done to meet the demand of tapping remaining oil during middle and later periods of oilfield development. Taking Kexia formation in Wu 2 xi of Karamay oilfield as an example, joint-well sedimentary profile is made according to principle of isochronous contrast and utilizing logging curves and core data, contrast of layers is fulfilled based on contrast of standard well, sedimentary cycle, microfacies and connectivity of sandbody. It is considered that formation S-7 is fan-delta sedimentary, and S+4-7 is main production layer, thick is large and distribution is extensive in the north of the block, connectivity is gradually good, thick becomes thin, area is small, connectivity is poor form north to south and west, the change is great in the horizontal, distribution is scattered. The method is effectivel, and worth popularizing in the refined description of the similar oil reservoir during the development of oilfield.