Characteristics and origin of reservoirs of gas fields in the Upper Paleozoic tight sandstone, Ordos Basin
Fu Jinhua1，3 Wei Xinshan2,3 Nan Junxiang2,3 Shi Xiaohu2,3
1 PetroChina Changqing Oilfield Company，Xi′an 710018，Shaanxi 2 Research Institute of Exploration and Development，PetroChina Changqing Oilfield Company，Xi′an 710018，Shaanxi
Abstract：The reservoirs in the Upper Paleozoic of Ordos Basin are generally characterized by low porosity and low permeability，but reservoirs with relatively high quality developed in the background of low porosity and low permeability. By means of the polarizing microscope，rate-controlled mercury penetration and other technical methods，based on the analysis of clastic rock granularity，detrital composition and pore structure，comparison and origin analysis of the tight sandstone reservoirs in gas fields，including Shenmu Gas Field，Yulin Gas Field and Sulige Gas Field，were carried out.We concluded that higher content of quartz kind of minerals and adequate amount of soluble components(including feldspar minerals，volcanic rock debris and tuffaceous materials，etc)and the seepage channels for acidic fluid formed by remnants of intergranular pore-space are requirements for relatively high quality reservoirs;higher content of phyllites rock fragments and argillaceous slates，which were deformed under the overlying strata pressure，led to the intense decrease of intergranular pore-space and the lack of seepage channel for acidic fluid，and thus tight sandstone reservoirs with low porisity and low permeability were developed.
Fu Jinhua,Wei Xinshan,Nan Junxiang et al. Characteristics and origin of reservoirs of gas fields in the Upper Paleozoic tight sandstone, Ordos Basin[J]. JOPC, 2013, 15(4): 529-538.
