关键词: 塔里木盆地, 奥陶系, 探井, 天然气

Abstract: Guchengxu uplift located in the east side of central uplift in Tarim basin indicates that the Ordovician strata are complete, and the grain limestone and porous-type reservoirs in Yijianfang formation of Middle Ordovician-Yingshan formation of Lower Ordovician are newly discovered in this area. The reservoirs rocks are characterized by intergranular pores, intercrystal pores and pinpoint-like solution pores, with micro-fissures and sutures as channels, shaping 2~50 m thick and wide spreading layered porous-type reservoirs with 4 percent of porosity given by the interpretation of imaging logging data. The study shows that such reservoirs were mainly controlled by distribution of tableland marginal sand-bank facies, and post-solution was advantageous to improvement of their storage performances; the good reservoir-cap rock assemblage was formed by the grain limestone reservoirs and overlying shale of Upper Ordovician as the regional cap rocks; the good sealing nature allowed to shape multilayer and potential reservoirs under multistage fillings of highly matured hydrocarbons in the source area. Gas flow from a well drilled and completed in this area by drillstem test has fully revealed its tremendous potentials for petroleum exploration here.

Key words: Tarim basin, Ordovician, prospecting well, natural gas