鄂尔多斯盆地五蛟地区长7段致密砂岩物性分级评价

非常规油气资源逐渐成为我国油气产量的重要增长点,其中,致密油是非常规油气研究的热点。鄂尔多斯盆地致密油的勘探开发程度相对滞后,提升致密油勘探开发效率的关键在于优选“甜点”区(段),而刻画“甜点”区(段)的关键在于致密储层的物性分级评价。利用压汞数据、铸体薄片和扫描电镜资料对致密砂岩孔喉结构进行表征,并结合分形理论,建立了适合鄂尔多斯盆地五蛟地区长7段致密砂岩的孔喉分类方案:大孔喉(喉道半径r>0.2μm)、中孔喉(0.08<r≤0.2μm)、小孔喉(0.025≤r≤0.08μm)和微孔喉(r<0.025μm)。依据不同类型孔喉的发育程度,进一步将致密砂岩划分为4类:Ⅰ类砂岩(孔隙度Ф>10%,渗透率K>0.15mD)、Ⅱ类砂岩(Ф>8%,0.075mD≤K≤0.15mD)、Ⅲ类砂岩(Ф>6%,0.05mD≤K≤0.075mD)、Ⅳ类砂岩(Ф<6%或者K<0.05mD)。该分级方案得到了试油资料的验证,高产井主要分布在Ⅰ、Ⅱ类砂岩发育的地区。研究区Ⅰ、Ⅱ类砂岩主要分布在中南部,且在长71亚段更为发育。因此,研究区中南部是未来致密油勘探的有利区块,长71亚段是未来勘探的最有利层段,其次是长72亚段。

Sex and age classes of prey items (rats/mice) in the diet of the Barn Owl (Tyto alba) in Sindh,Pakistan

Barn Owl (Tyto alba) pellets were collected from nine locations and two districts of Sindh,Pakistan and 937 prey items were recovered from 619 pellets.Rats/mice (59.6%) were the most dominant food items consumed by the Barn Owl.Shrews (22.3%),bats (1.3%),birds (12.0%),insects (1.3%),frogs (2.2%) and plant materials (1.3%) were found in their diet as well.Study of the pelvic girdle bones of rats/mice,used only for sexing,proved to be a useful device in population dynamics.In the pelvic bone,pelvic symphysis is found only in female rats/mice developed as a result of sex hormones that occur during gestation.Among the diet of rats/mice,males were found to be significantly dominant.Tooth wear patterns on the occlusal surfaces of molariform teeth of the rats/mice were found to provide an effective criterion for establishing age classes of rats/mice.In the present study,adult rats/mice were found to be dominant over sub-adults and old adults.ANOVA showed significant differences in the number of rats/mice and shrews (prey items) and the other prey items/plant materials in the diet of Barn Owls in the district Thatta and district Karachi.Chi-square test disclosed non-significant differences in age and sex categories.