大连地下石油储备库初始渗流场数值反演

 初始渗流场分析是水封式地下石油储备库设计中的重要内容和先决条件，现场压水试验只能提供较准确的各向同性渗透系数，而不能反映各向异性的渗透特征。结合大连地下石油储备库工程，提出一种基于随机节理网络模拟技术反演岩体各向异性渗透特征的方法。首先，采用三维离散元程序3DEC内置的Fish语言，直接生成不同尺寸的三维节理网络模型，通过推导的判别式来统计模型中各组节理的个数及产状信息。其次，利用裂隙介质的渗透张量理论计算不同尺寸的岩体渗透张量，进而确定节理岩体的表征体元(REV)。根据现场压水试验实测资料，修正节理岩体的渗透张量，再利用Matlab软件计算渗透主值及渗透特征向量。最后，考虑渗透系数的空间正交各向异性，采用FLAC3D的Fl_anisotropic的渗流模型反演库区的初始渗流场，为水封式地下石油储备库水幕设计及稳定性分析提供较合理的初始渗流场条件。

INVERSION ANALYSIS OF INITIAL SEEPAGE FIELD OF DALIAN UNDERGROUND OIL STORAGE CAVERN

The initial seepage field analysis is prerequisite and important content for the water-tight underground oil cavern design. Although the field water pressure test can provide a more accurate isotropic permeability coefficient,which does not reflect the anisotropy permeability of jointed rock mass. In initial seepage field analysis of Dalian underground oil storage cavern,based on joins network simulation technique,a new method for calculating the anisotropy permeability is proposed. Firstly,different sizes of three-dimensional random joint networks are generated with the programming language Fish embedded within 3DEC. The values of joint geometric characters and number of random joints in each group are decided through the derivable formulas. Different sizes of rock permeability tensor are calculated based on fractured rock permeability tensor theory;meantime,with the size of three-dimensional random joint networks increasing,representative elementary volume is also determined until rock permeability tensor is not changed obviously. As the difficulty of fracture width measurement,some fracture fillings and the presence of non-connected,as well as the impact of fracture roughness,the calculated permeability tensor have a certain degree of error in value. It is necessary to amend according to field water pressure test. Principal value and characteristic vector of permeability tensor are easily calculated with Matlab software. Finally,considering the space orthotropic permeability coefficient,the initial seepage inversion is completed with the fl_anisotropic model within FLAC~(3D),the Fl_anisotropic model parameters are obtained from principal value and characteristic vector of permeability tensor. The inversion analysis provides initial seepage field for water-tight underground oil cavern water curtain design and stability analysis.