塔河油田奥陶系生物扰动型储集层的三维重构及启示意义*

塔河油田奥陶系鹰山组和一间房组生物扰动型储集层发育。在岩心观测的基础上,通过典型岩样切片、偏光显微镜、阴极发光显微镜和X射线显微镜观测以及XRD测试分析,对研究区奥陶系生物扰动型储集层的发育特征进行了研究。研究区奥陶系可识别的生物扰动分为2类,分别是 Thalassinoides和Helminthopsis,但以Thalassinoides最为发育,扰动体积可达90%;生物潜穴充填物以白云石颗粒为主,可达90%以上;宿主围岩为泥晶灰岩。随着塔河油田早—中奥陶世海侵、海退沉积环境的变化,生物潜穴的发育呈现出明显的周期性演化规律。在综合提取生物扰动型储集层特征信息的基础上,以沉积学和遗迹学理论为指导,应用3ds Max软件对研究区奥陶系生物扰动型储集层进行了三维重构。该研究虚拟再现了塔河油田生物扰动型储集层的内部结构与微观特征,不仅为后续研究这类储集层的宏观非均质性与微观各向异性、定量表征该类储集层微观尺度上的渗流特征奠定了基础,而且还为完善塔河油田奥陶系油藏模型提供了一种新思路。

Three-dimensional reconstruction and their significance of bioturbation-type reservoirs of the Ordovician in Tahe Oilfield

This paper studied the bioturbation-type reservoirs well-developed in the Ordovician Yingshan and Yijianfang Formations of the Tahe Oilfield based on core observation,cathodoluminescence microscopy,three-dimensional X-ray microscope,and X-ray diffractometer. Two kinds of trace fossils (i.e.,Thalassinoides and Helminthopsis) were identified;the former is most prevalent with the bioturbated volume up to 90%. The burrow infillings are composed mainly of dolomite,accounting for more than 90%. The host rock is micrite. Along with the change of depositional environment during the Early-Middle Ordovician transgression and regression in Tahe Oilfield,burrows also show obvious periodicity. Three-dimensional geological model of the bioturbation-type reservoir in the study area was established using the three-dimensional reconstruction software package by 3ds Max software. This study visualizes the internal structures and microscopic features of the bioturbation reservoir in Tahe Oilfield and provides a solid academic basis for subsequently investigating macro-heterogeneity and micro-anisotropy,quantitatively characterizing the percolation characteristics on the microscopic scale of those bioturbation reservoirs. In addition,it also provides a new idea to improve and perfect the model of Ordovician reservoir of Tahe Oilfield.