变形介质的变形机理及物性特征研究

变形介质气藏在开发过程中,孔隙压力随流体的流出而下降,使储层内外压差增大,孔隙受到压缩而体积缩小,孔隙度和渗透率随之降低,极大地影响到此类气藏的开采。主要阐述了多孔介质发生变形的类型,并从多孔介质的微观物理特性(包括物质组成,单元体类型及它们之间的接触关系、排列方式和胶结方式)来分析对其发生变形的影响。还通过实验,分析了变形介质的孔隙体积、孔隙度和渗透率随压力而发生的变化规律。实验表明,随着净围压的升高,孔隙体积缩小,孔隙度和渗透率降低。与孔隙度相比较,渗透率受压力变化的影响更明显。因而,在变形介质气藏的开采过程中,保持气藏内部的原始压力对稳产、高产及延长气藏的开采时间有重要意义.

RESEARCH ON DEFORMATION MECHANISM AND PETROPHYSICAL CHARACTERISTICS OF DEFORMABLE MEDIA

In the process of developing deformable-media gas fields, the pore pressure decreases when fluids flow out of the reservoir, and the difference of pressure inside and outside the reservoir increases. As a result, pore volume, porosity and permeability decrease. These changes significantly affect the recovery performance. The present work discusses the mode of deformation of porous media, analyzes the influence of microscopic physical properties (material constituents, unit type and their contacting, arrangement and cementation patterns) on deformation, and experimentally studies the regularity of changes of pore volume, porosity and permeability with the variation of pressure. The experimental results show that the pore volume, porosity and permeability decrease with the increase of net confining pressure, and that permeability is more sensitive to pressure changes than that of porosity. Therefore, in developing deformable-media gas fields, maintaining the original reservoir pressure is important to stabilize and improve production and to prolong production life.