基于格子Boltzmann方法的致密气藏微尺度效应研究

发布时间：2018-01-07 14:27

本文关键词：基于格子Boltzmann方法的致密气藏微尺度效应研究　出处：《断块油气田》2016年06期 　论文类型：期刊论文

【摘要】：致密储层孔隙结构复杂,气体在致密孔喉中的流动存在微尺度效应,宏观流动规律难以准确描述其渗流特征。针对致密多孔介质孔隙主要分布在微纳米尺度的特点,建立修正克努森数(Kn)、固体边界处考虑镜面反弹(边界滑移效应)的格子Boltzmann模型。通过模拟压差驱动下的二维平板流动,验证了模型的正确性,并分析了克努森数对流动速度的影响。基于随机生长四参数生成法,对致密储层的二维微观孔隙结构进行了重构,利用修正格子Boltzmann模型进行流动模拟。结果表明:气体在致密储层中的流动存在微尺度效应,滑脱效应使得通道中间部分流体速度增大;在一定的压力梯度下,渗透率随着克努森数的增加而呈线性增加;克努森数不变时,渗透率随着平均压力倒数的增加而呈线性增加,即随着平均压力的增加,岩心的绝对渗透率减小。
[Abstract]:The pore structure of the tight reservoir is complex, and the flow of gas in the tight pore throat has microscale effect. It is difficult to describe the percolation characteristics of macroporous media accurately. Aiming at the distribution of pores in dense porous media on micro- and nanoscale scale, a modified Knudsen number (Kn) is established. The lattice Boltzmann model with mirror rebound (boundary slip effect) is considered at the solid boundary. The validity of the model is verified by simulating the two-dimensional plate flow driven by pressure difference. The influence of Knudsen number on the flow velocity is analyzed. Based on the method of generating four parameters of random growth, the two-dimensional micro-pore structure of tight reservoir is reconstructed. The modified lattice Boltzmann model is used to simulate the flow. The results show that there is a microscale effect in the flow of gas in the tight reservoir, and the slippage effect increases the velocity of the fluid in the middle part of the channel. Under a certain pressure gradient, the permeability increases linearly with the increase of Knudsen number. When the Knudsen number is constant, the permeability increases linearly with the increase of the reciprocal of the mean pressure, that is, the absolute permeability of the core decreases with the increase of the average pressure.
【作者单位】：中国石油大学(北京)石油工程教育部重点实验室;中海油研究总院开发研究院;
【基金】：国家自然科学基金项目“基于孔隙网络模型的多孔介质近混相油气水三相流动模拟研究”(11072268)
【分类号】：TE312
【正文快照】： 随着非常规油气资源日益受到重视,致密气藏的勘探开发逐渐成为热点[1￣3]。由于致密储层岩性致密,渗透率极低,实验时对设备和技术人员要求较高,常规的实验方法难以保证实验数据的准确性和精度。作为一种介观模拟方法,格子Boltzmann方法可以对处理过的多孔介质图像进行流动仿真

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