碳酸盐岩酸蚀蚓孔双重分形描述方法  

Dual fractal model of carbonate acidizing wormholes

作　　者：张合文[1] 邹洪岚[1] 刘双双[1] 鄢雪梅[1] 梁冲[1] 

机构地区：[1]中国石油勘探开发研究院,北京100083

出　　处：《天然气地球科学》2017年第3期466-472,共7页Natural Gas Geoscience

基　　金：国家自然科学基金项目"复杂非均质碳酸盐岩储层水平井酸化高效布酸基础理论研究"(编号:51474182);国家科技重大专项"复杂碳酸盐岩油气藏采油采气关键技术研究与应用"(编号:201700503005)联合资助

摘　　要：基质酸化是碳酸盐岩油气藏中应用范围最广、最经济有效的增产方式之一,而酸化最典型的特征是形成酸蚀蚓孔。由于酸岩反应影响因素多、蚓孔形态多样、生长随机性强,目前仍未形成对蚓孔的定量描述方法。对碳酸盐岩酸蚀蚓孔的定量描述主要包括确定单蚓孔形态及多蚓孔分布2部分内容,这是优化施工设计、经济有效开发此类油气藏的重要前提。为此,通过多组岩心流动实验,采用三维CT扫描后重组的手段得到了蚓孔的真实形态,并验证了岩心线性和径向流动下蚓孔的分形特征,得到了其分形维数。运用分形几何学方法,建立了单蚓孔等效长度分形计算模型,为从长度和平面分布2个维度定量描述单蚓孔提供了可能。其次,为了明确不同蚓孔在空间分布情况,建立了多蚓孔间竞争分布数学模型,并对其进行了求解和模拟分析,验证了蚓孔间竞争分布的分形性特征。在此基础上,建立了蚓孔分布双重分形模型,为定量描述三维酸蚀蚓孔形态奠定了基础,也为更准确优化酸化施工提供了可能。Matrix acidizing is one of the most popular and cost-efficient method for carbonate stimulation.The main characteristic of carbonate acidizing is forming wormholes.Until now,there is no effective model to describe these wormholes quantitatively,because of so many affecting parameters,wormhole types and their growing randomness.There are two main parts to calculate carbonate acidizing wormholes parameters,distribution and its length of single wormhole and competition relationship between several wormholes.This is an important prerequisite to optimize the acidizing treatment design and develop such carbonate reservoir cost-effectively.To this end,several sets of core flow experiments were completed,and the actual shape of wormhole were reorganized using three dimensional computed tomography scan facility.By analyzing these wormholes,fractal characteristic was proved to be both of linear and radial flow status.Their fractal dimensions,which are key parameter for describing fractal geometry,were given then.Based on previous conclusions,fractal model of dingle wormhole equivalent length was established,which make it possible to describe wormhole considering both length and plane distribution.Secondly,in order to clarify the relationship between several different wormholes,competition mathematic model of multiple wormholes was given.After solution and simulation analysis of this model,its fractal characteristic and fractal dimension were also obtained.On this basis,dual fractal mathematic model of wormholes was finally established,which make it possible to describe three-dimensional shape of wormhole quantitatively and optimize a more accurate acidizing treatment design.

关 键 词：采油/气工程 酸化 碳酸盐岩 酸蚀蚓孔 分形 

分 类 号：TE357[石油与天然气工程—油气田开发工程]