塔里木盆地志留系沥青砂岩有效厚度的确定方法

塔里木盆地志留系具有分布广泛的沥青砂岩,沥青砂岩段厚度在各个地区具有不均匀性,从几米到一百多米不等。岩心观察发现沥青砂岩段内并不全含有沥青,岩心剖面上呈现“黑白砂相间”的现象,“黑砂”的部分为含沥青层段,“白砂”的部分为不含沥青层段。弄清“白砂”中曾经是否有油气进入,对志留系沥青砂岩中沥青含量、古油藏油气储量的计算及志留系剩余油气资源量的评价具有重要的意义。本文通过对志留系沥青砂岩段的“黑砂”与“白砂”分别取样,采用物性测定、显微镜下岩性观察、含油包裹体颗粒指数(GOI)数据观测及定量颗粒荧光(QGF)指数测定等多种方法和技术手段对沥青砂岩段的“黑砂”与“白砂”进行对比研究。结果表明,沥青砂岩段的“白砂”没有油气进入或进入的油气量很少,在确定志留系沥青砂岩有效厚度时应剔除“白砂”层的厚度。

Determination Methods of Effective Thickness of Silurian Bituminous Sandstone in the Tarim Basin

The distribution of bituminous sandstone is extensive in Silurian in the Tarim Basin, and its thickness varies largely in different areas, ranging from several meters to more than one hundred meters. It is discovered by observing cores that bituminous sandstone segments are not full of bitumen. In intercalation of black sandstone and white sandstone, only the black part contains bitumen. Whether hydrocarbon once migrated into the white sandstone is very important to the calculation of the quantity of bituminous sandstone and reserves of original petroleum pool, and to the evaluation of residual resources in the Silurian rocks. Samples of black sandstone and white sandstone are collected separately and compared by means of physical property demarcation, observing lithology by microscope, grains containing oil inclusion (GOI) technology and quantitative grains fluorescence (QGF) technology. The results show that there was little hydrocarbon, or none, migrated into the white sandstone of bituminous sandstone segments, and therefore, the thickness of white sandstone should be deducted to determine effective thickness of bituminous sandstone.