DEFORMATION THEORY AND STRESS SENSITIVITY OF TIGHT SANDSTONES RESERVIORS
致密砂岩油气储层岩石变形理论与应力敏感性

During exploiting the tight sandstone oil and gas reservoirs, the descent of pore pressure will induce the virtual stress increase, which makes the formation rocks deformation and the porosity permeability descent. The theories and the deformation reasons about the tight sandstone are analysed from rock mechanics point of view in this article. With the virtual stress alteration, the tight sandstone samples porosity and permeability change rule has been studied by the stress sensitivity experiment. The result shows that the porosity volume and the fracture width change are the main issues of the tight sandstone deformation, the deformation types in tight sandstone oil and gas reservoirs are mainly about elastic deformation and elastic-plastic deformation. The interior factors of tight sandstone result in tight sandstone deformation, such as grain's rigidity, contact and cementation relationship between grains, the characters of fracture in tight sandstone, and so on. With the virtual stress increase, the tight sandstone porosity volume and the width of the fracture are compressed, the permeability of the tight sandstone decrease in much extent, which will lead to a serous formation damage.