基于频变属性的储层连通性评价

发布时间：2018-04-02 22:03

本文选题：流度属性　切入点：K_1属性　出处：《成都理工大学》2017年硕士论文

【摘要】：渗透率作为储层的一种重要物性,表征储层的连通性和流体的流动能力,能在流体的分布、油气开发中发挥重要作用。从低频地震信号中提取的成像属性和流度属性包含了储层渗透率和流体黏滞系数两项重要参数的信息,能够体现储层所含流体的活动能力,而结合地震高频信号和低频信号的1属性能够表征裂缝储层的连通性。因此,成像属性、流度属性和1属性的应用价值越来越受到油气地球物理解释界的重视。尽管目前成像属性和流度属性在储层流体流动能力评价中已经有一些应用,但有一些关键问题仍需要进一步研究:1、储层内部透镜体互层的影响,成像属性和流度属性的计算公式来源于储层顶部的低频渐近反射系数,该反射系数只考虑了界面处的反射,而实际的地震反射信号不仅仅是地震波在界面处的反射,还可能包含了储层内部多层透镜体互层的反射信息。2、优势频率的选取,优势频率对于成像属性和流度属性的计算至关重要,常用的方法是人工选取,这样致使提取出的属性体人为干扰因素较大,不能真实反映储层流体的活动能力。针对上述问题,本文基于岩石物理,探讨了常规的流度属性和1属性的适用条件;从考虑多层反射的渐近反射系数表达式出发,解决了优势频率的选取问题,消除了储层互层的影响,主要的工作内容和认识有:(1)介绍了基于渗流理论的饱和流体多孔介质的顶界面反射机制,分析了低频渐近反射系数与渗透率、黏滞系数和频率的关系,说明了地震低频信号包含了储层物性和流体流动能力的信息,并阐述了低频渐近反射系数和成像属性、流度属性的推导过程。在上述的研究的基础上利用两个属性的计算公式对比了成像属性和流度属性的优缺点,实例应用结果表明流度属性在对储层流体活动能力的评价中要优于成像属性。(2)基于双重孔隙介质模型,应用数值模拟分析了不同顶底波阻抗差异情况下的流度属性和1属性对渗透率变化的响应特征,结果表明两个属性对于渗透率的变化有着明显的反映。从总体趋势看,流度属性随渗透率的增大而增大,1属性则与模型有一定关系。数值模拟结果为这两个属性的应用提供了依据。实例证明,两个属性结合使用能有效反映储层流体的流动能力,明显降低了单个属性进行储层连通性预测的多解性和不确定性。(3)引入了考虑储层内部多层透镜体反射的等效渐近反射系数,数值模拟了反射系数因子随频率和层厚的变化,对优势频率的选取增添了理论基础。从等效的渐近反射系数出发,重新推导了流度属性的计算公式,考虑了储层内部多层透镜体对流度属性的影响,从而降低了由储层厚度给流度属性在实际应用中带来的不确定性。
[Abstract]:As an important physical property of reservoir, permeability can play an important role in the distribution of fluid and the development of oil and gas by characterizing the connectivity of reservoir and the flow ability of fluid.The imaging attributes and mobility attributes extracted from low-frequency seismic signals contain the information of two important parameters, reservoir permeability and fluid viscosity coefficient, which can reflect the mobility of the fluid contained in the reservoir.Combining the 1 attribute of seismic high frequency signal and low frequency signal, the connectivity of fractured reservoir can be characterized.Therefore, the application value of imaging attribute, mobility attribute and 1 attribute has been paid more and more attention to by geophysical interpretation of oil and gas.Although there have been some applications of imaging and mobility attributes in the evaluation of reservoir fluid flow capacity at present, there are still some key issues that need to be further studied to study the influence of the internal lens interbedded in the reservoir.The formulas for calculating imaging and mobility attributes are derived from the low frequency asymptotic reflection coefficients at the top of the reservoir, which only consider the reflection at the interface, while the actual seismic reflection signals are not only the reflection of seismic waves at the interface.It may also contain reflection information of interlayer of multi-layer lens in reservoir. The selection of dominant frequency and dominant frequency are very important to the calculation of imaging attribute and mobility attribute. The commonly used method is manual selection.As a result, the extracted attribute bodies can not truly reflect the activity ability of reservoir fluids because of the large human interference factors.In view of the above problems, based on rock physics, the conventional mobility attribute and the applicable condition of 1 attribute are discussed, and the problem of selecting dominant frequency is solved based on the expression of asymptotic reflection coefficient considering multi-layer reflection.In this paper, the influence of interbedded reservoir is eliminated. The main work content and understanding are: (1) the reflection mechanism of the top interface of saturated fluid porous media based on seepage theory is introduced, and the relationship between the low frequency asymptotic reflection coefficient and permeability, viscosity coefficient and frequency is analyzed.The information of reservoir physical property and fluid flow capacity is included in the low frequency seismic signal, and the derivation process of the low frequency asymptotic reflection coefficient, imaging attribute and mobility attribute is described.On the basis of the above research, the advantages and disadvantages of imaging attribute and mobility attribute are compared by using the calculation formula of two attributes.The application results show that mobility attribute is superior to imaging attribute in evaluating reservoir fluid activity based on dual pore media model.Numerical simulation is used to analyze the mobility properties and the response characteristics of the 1 attribute to the permeability change under the condition of different impedance of the top and bottom wave. The results show that the two attributes have obvious effect on the permeability change.From the general trend, mobility attribute increases with the increase of permeability, which is related to the model.The numerical simulation results provide the basis for the application of these two attributes.Examples show that the combination of two attributes can effectively reflect the flow capacity of reservoir fluid.The multiplicity and uncertainty of reservoir connectivity prediction by single attribute is obviously reduced.) the equivalent asymptotic reflection coefficient considering reflection of multi-layer lens in reservoir is introduced, and the variation of reflection coefficient factor with frequency and layer thickness is numerically simulated.It adds the theoretical basis to the selection of dominant frequency.Based on the equivalent asymptotic reflection coefficient, the calculation formula of mobility attribute is rededuced, and the influence of convective property of multi-layer lens in reservoir is considered.Thus, the uncertainty caused by the mobility attribute of reservoir thickness is reduced.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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