Characterization of a Geothermal Reservoir Crack Based on the Analysis of Dynamic Response of a Crack Filled with Fluid

基于充液裂缝动态响应分析的地热储层裂缝表征

基本信息

批准号：
08650086
负责人：
HAYASHI Kazuo
金额：
$ 1.22万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1997
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08650086/
关键词：
Geothermal Energy HDR Geothermal Reservoir Crack Characterization of Crack AE Elastic Wave

项目摘要

The objective of the present project is the establishment of a method for characterizing the geometrical and physical characteristics of a fluid-filled geothermal reservoir crack. Firstly, we have proposed a model for a fluid-filled crack within an elastic medium with permeation of fluid. The upper and lower surfaces are in partial contact to each other, thus there exists interface stiffness along the crack, and also the fluid viscosity is taken into account. It has been revealed that, in the case that the partial contact is absent, the eigen angular frequencies are highly dependent on the aspect ratio (the ratio between the crack size and aperture), when the viscosity and permeability are small. However, in the case that the partial contact is present, the eigen angular frequencies are highly dependent on the interfacial stiffness. When the permeability is large as that of a formation in a usual geothermal field, then the effects of the permeability and viscosity become stronger. In order to get clear understanding of the effects of permeability and fluid viscosity, we have analyzed the case that the rock is rigid and have found that there exists an optimum value of fluid viscosity which gives the largest pressure response. The optimum value of fluid viscosity is mostly determined by the permeability of the formation. Inversely speaking, it is possible to get the maximum pressure response by choosing the fluid with the optimum value of viscosity depending on the formation permeability. Finally, on the basis of the results of the analysis, we have set up the inverse problem to estimate the aspect ratio of the crack, the initial crack aperture and the interfacial stiffness by using a newly introduced objective function.

本项目的目的是建立一种表征流体填充地热储层裂纹的几何和物理特征的方法。首先，我们提出了一个模型，用于透明流体的弹性培养基中充满流体的裂纹。上表面和下表面彼此部分接触，因此存在沿裂缝的界面刚度，并且考虑了流体粘度。已经揭示了，在没有部分接触的情况下，当粘度和渗透率较小时，特征角频率高度依赖于纵横比（裂纹尺寸和光圈之间的比率）。但是，在存在部分接触的情况下，特征角频率高度取决于界面刚度。当渗透性像通常的地热场中的形成一样大，那么渗透性和粘度的影响就会变得更强。为了清楚地了解渗透性和流体粘度的影响，我们分析了岩石是刚性的案例，并发现存在最佳的流体粘度值，从而产生了最大的压力响应。流体粘度的最佳值主要取决于形成的渗透性。相反，可以通过选择粘度的最佳值来获得最大压力响应，具体取决于粘度的最佳值。最后，根据分析结果，我们通过使用新引入的目标函数来估算裂纹，初始裂纹孔径和界面刚度的纵横比的反面问题。