双相薄（互）层介质背景上发育定向裂隙的OA介质视各向异性适用性和波场特征分析

Orthotropic anisotropy (OA) medium reservoirs with directional fractures on the background of two phase thin (inter) layer media is typical types of reservoirs with fractured coal seams, unconventional tight sandstones and shale in China. How to use seismic data apply accurate inversion is a difficult problem to be solved in exploration and development. Due to the serious over-determination problem in the inversion of such media reservoirs, the inversion results are multi-solving and unreliable. The existing research results are lacking in the thin (inter) layer VTI background parameters and the two-phase medium parameters of the OA medium for the analysis of the AVO and AVAZ characteristics of the seismic P and Ps waves. The derived OA medium apparent anisotropy approximation formula also lacks systematicity and model targeted. In response to these problems, the application proposes to establish three typical basic OA media models, and gradually fill multiple sets of multi-angle cracks and different fluid-derived complex OA media models, analyze their anisotropic approximation and accurately simulate the seismic response characteristics. Background thin (inter) layer VTI inter layer surrounding rock parameters, frequency, fracture combination parameters, fluid parameters, network orientation and other aspects of the applicability of the anisotropy theory, giving higher precision apparent anisotropy approximation formulas for different OA models. The apparent anisotropy approximation formula provides a theoretical basis for the inversion of OA media for the development of directional fractures on the background of two phase VTI media.

双相薄（互）层介质背景上发育定向裂隙的正交各向异性（OA）介质储层是我国含裂隙煤层、非常规致密砂岩和页岩等储层的典型类型，如何利用地震资料对其进行准确反演是勘探开发需要解决的难点问题。由于此类介质储层反演中存在严重的超欠定问题，使得反演结果出现多解性和不可靠性。已有的研究成果在OA介质的薄（互）层VTI背景参数和双相介质参数对地震纵横波AVO和AVAZ特征分析上较为缺失，推导的OA介质视各向异性近似公式也缺乏系统性和模型针对性。针对这些问题，申请拟建立三种典型的基础OA介质模型，并逐步填充多组多角度裂隙和不同流体衍生多种复杂OA介质模型，分析它们的各向异性近似和精准模拟波场特征，从背景薄（互）层VTI的互层、围岩、频率、裂隙组合参数、流体参数、测网布置方位等多个角度讨论视各向异性理论的适用性，给出针对不同OA模型的更高精度的视各向异性近似公式，为复杂OA介质反演提供理论基础。

随着油气勘探开发的需求不断深入，圈闭性和厚砂岩储层已经基本得到了深度开发，广泛发育的薄（互）层岩性储层成为陆上和海上油气储层预测和开发的重点和难点，此外具有薄（互）层发育定向裂隙的OA介质储层特征的致密页岩油气储层也成为勘探开发的主要目标。地震数据分辨率往往无法直接对薄（互）层和裂隙进行有效识别和描述，此类介质储层反演中存在超欠定问题，使得反演结果出现多解性。现有的研究成果在OA介质的薄（互）层双相介质参数对地震波场特征分析上较为缺失，缺乏系统性和模型针对性的双相OA介质视各向异性理论和应用研究。因此，本项目在等效VTI薄互（互）层理论研究的基础上，对薄（互）层发育定向裂隙的OA介质进行建模、模拟和数值分析等进行了系统的研究。项目研究过程中给取得了如下进展和成果：(1) 建立了不同沉积环境和岩性的OA介质模型数据，构建了较为典型的三种VTI背景下的OA介质模型；（2）在长波长等效理论背景下，引入了裂隙等效模型Schoenberg 线性滑动模型和OA介质刚度系数矩阵等方程，推导了双相薄（互）层介质背景上发育定向裂隙的OA介质视各向异性近似公式；（3）对三种典型模型的地震波波场进行分析，发现决定波场特征的主要因素是互层厚度、围岩结构、裂隙参数，获得了识别典型储层的地震属性；（4）根据理论分析，发展了分频后高频地震信号控制下的薄互层地震数据进行高分辨率拓频方法，并在引伸研究中得到了应用。