Because of the low porosity, low permeability, various clay minerals, complex pore structure and so on, tight sandstone reservoir is easy to cause serious reservoir damage in the process of the exploration and development. Taking the tight sandstone reservoir of Oilfield M in Central Ordos Basin as the research object, on the bases of the studies on the petrological characteristics, physical properties and pore structure characteristics, the reservoir sensitivity evaluations were carried out, and moreover the mechanisms of the sensitivity damage were analyzed. The results show that the tight sandstone reservoirs have medium to weak velocity sensitivity, strong water sensitivity, strong salt sensitivity, weak to medium alkali sensitivity, no acid sensitivity to weak acid sensitivity and strong stress sensitivity, the degrees of the sensitivity damage are the water sensitivity > the stress sensitivity > the salt sensitivity > the speed sensitivity > the alkali sensitivity > the acid sensitivity;the sensitivity damage mechanisms are mainly related to the clay mineral composition and the pore structure, among them, the rather higher contents of the illite/montmorillonite mixed formation and montmorillonite are the most important factors to form the strong water sensitivity and strong salt sensitivity, the presence of the kaolinite is the main factor to cause the velocity sensitivity, the presence of the chlorite makes the partial rock samples show weak acid sensitivity, the dissolutions of the quartz particles and aluminosilicate minerals are the most main causes of the alkali sensitivity, the complex pore structure, easy-to-deform sheet throat, weaker clay mineral strength and effective stress change are the main reasons for the reservoir with strong stress sensitivity. The study results can provide the references for the high-efficiency exploration and development of the target block and similar tight sandstone reservoirs.
Petroleum Geology & Oilfield Development in Daqing
tight sandstone reservoir