非常规油气致密储层微观孔喉结构表征新技术及意义

New Micro-throat Structural Characterization Techniques for Unconventional Tight Hydrocarbon Reservoir

非常规油气致密储集体以纳米、微米孔喉为主,微观孔喉结构特征是决定其低孔低渗的主要因素,也是建立非常规油气储层评价标准,揭示油气形成因素、富集规律等基本地质特征的基础。目前,非常规油气致密储层微观孔喉表征技术主要利用了纳米材料科学、物理化学以及分析化学等学科研究方法,通过二维场发射扫描电镜等图像直接观测、气体吸附等间接数值测定以及X-CT三维数值重构模拟孔隙结构三类技术方法,在孔喉大小、形态、分布、三维连通性等方面取得了初步进展,提高了纳米级微观孔喉结构的表征精度。但孔喉结构特征表征技术仍在测试原理、多类型数据融合、多技术手段联合与实验前处理、多尺度特征表征等方面值得进一步探索,该研究也将为准确评价有利致密储层发育区、致密油气等非常规油气甜点区提供依据。

Nano-scale and micro-scale pore throats dominate the unconventional tight oil and gas reservoirs. Pore-throat microscopic structure is a key factor to lead to the low-permeability and low-porosity reservoir features. It is also the foundation to establish the criteria for evaluation of unconventional oil and gas reservoirs and interpret the basic geologic features, such as hydrocarbon occurrence and accumulation. Currently, microscopic pore-throat characterization techniques for unconventional tight oil and gas reservoir are based on nanoscale material science, physical chemistry and analytical chemistry. Initial progress has been made in the study of pore size, morphology, distribution and 3D connection by means of direct image observation under field-emission scanning microscope, indirect numerical value measurement such as gas absorption, and 3D value reconstruction modeling pore structure by X-CT, improving the characterization accuracy of nano-scale microscopic pore-throat structure. However, more efforts are required to improve pore-throat structural characterization techniques in the areas of principle testing, integration of multi-data, combination of multi-techniques and pre-experiment disposition, and multi-scale feature characterization. This study will provide the data for precise evaluation of favorable tight reservoir, tight oil and gas zones and other unconventional hydrocarbon sweet spots.