THE RESERVOIR CHARACTERISTICS AND ITS PETROLIFEROUS SIGNFICANCE IN THE DEVONIAN DONGHETANG FORMATION, TAHE AREA, THE TARIM BASIN

The sandbodies of the Devonian Donghetang Formation were trended in direction of S-N in Tahe area,the Tarim Basin,with thick in the northwest and thin in the southeast.The reservoir rocks consisted of quartz sandstone,feldspathic litharenite and subarkose.The pore types of the reservoirs were mainly residual intergranular pore,intergranular dissolved pore and intragranular dissolved pore.The diagenesis of the Donghe sandstones in the area could be divided into the compaction,clay cementation,quartz overgrowth,carbonate cementation and solution.The sandstones were of middle-low porosity with a mean of 11.25% and of middle-low permeability with a mean of 23.99×10^-3μm² because of their sedimentation and diagenesis.According to the physical property and the criterion of evaluation of reservoirs,the reservoirs are sorted into three types and eva-luated respectively.It was indicated that the hydrocarbon-bearing capability of the reservoirs were controlled by sedimentary environment,lithologies and physical properties.