低孔低渗储层测井解释方法研究──以陕甘宁盆地中部气田上古生界求孔隙度、渗透率为例

INTERPRETATION FOR WELL LOGGING DATA FROM LOW POROSITY AND PERMEABILITY RESERVOIRS──Exemplified by Porosity and Permeability calculation for Upper Palaeozoic Reservoirs in the Central Gas Fields of the Erdos Basin

本文论述了陕甘宁盆地中部气田上古生界测井解释方法，提出二叠系石盒子组与山两组砂岩包括石英砂岩和岩屑砂岩两部分，前部分岩石的骨架参数Ｐｍａ＝２．６５８ｇ／ｃｍ３，△ｔｍａ＝１８２μｓ／ｍ，后部分的Ｐｍａ＝２．７ｇ／ｃｍ３，△ｔｍａ＝１６４μｓ／ｍ；计算孔隙度用密度、声波孔隙度最小值及地区经验方程两种方法，其中以密度、声波时差孔隙度最小值为最佳，其公式为中Φ＝ｍｉｎ（ΦＤ，ΦＳ）；计算渗透率用粒度中值、岩石比面和束缚水三种方法，其中以粘度中值，孔隙度与自然伽玛相对值回归方程效果最佳，其公式为：上述研究成果已通过６６口井的验证，效果良好。

Based upon the interpretation for well logging data from the Upper Paleozoic Central Gas Fields of the Erdos Basin, it is suggested that the sandstones of the Permian Shihezhi and the Shanxi Groups can be distinguished mineralogically into quartz sandstone and lithic sandstone. The matrix parameters of these two sandstones are estimated to be Pma=2.65g/cm3, △tma= 182μs/m and Pma= 2. 7g/cm3, △tma= 164μs/m respectively. Porosity values were calculated by both density-minimum acoustic wave porosity and empirical equation methods. The density-minimum acoustic wave time difference porosity method with an equation of Φ=min(ΦD,ΦS ) appears to have yielded the best results. The calculations for permeability were performed by medium value of grain size, specific surface of rocks and bound water methods. The best results seems to have been given by the regressions between medium value of grain size, porosity and relative natural gamma values with the following equations:The calculations have been well verified by the practical data from 66 wells.