涩北一号气田疏松砂岩储层测井解释方法研究

THE LOGGING INTERPRETATION METHOD FOR THE LOOSE SANDSTONE RESERVOIRS OF NO.1 GAS FIELD IN SEBEI

涩北一号气田的主力产层是第四系疏松砂岩,成岩性差、砂泥岩交互,饱和度确定及流体解释困难。储层岩性以粉砂岩为主,孔隙度主要分布在28%～34%之间,渗透率主要分布于10.0～100.0md之间,为高孔中低渗储层。由于储层饱含天然气,单孔隙度模型精度难以保证,本文结合取芯井建立了密度-中子的二元回归孔隙度模型;而且地层泥质含量普遍偏高,其对渗透率的影响非常明显,于是建立了相对自然伽马-相对自然电位的二元回归渗透率解释模型。针对含气饱和度计算困难的问题,本文进行研究,提出四种计算方法,通过和实际生产数据对比,本文选取的改进阿尔奇和西门度公式结合计算含气饱和度的方法适用于本区,流体性质吻合率达到了88.89%,对该区生产具有指导意义。

Quaternary loose sandstone is the principal producing formation of No.1 gas field in Sebei. There are many difficulties in calculating gas saturation and identifying fluid type because of poor diagenesis, interbedded sand and shale.Its lithology is mainly siltstone. Porosity is distributed between 28%~34% and permeability is between 10.0~100.0 md. It belongs to high-porosity and middle-permeability reservoir.As the reservoirs are saturated by natural gas,it is difficult to ensure the accuracy of single porosity model. The density-neutron twovariable regression porosity model is established combining with coring well. Shale content is general high in the formation which has obvious effect on permeability. Therefore the twovariable regression permeability interpretation model of relativelynatural gamma-relatively spontaneous potential is established. According to the difficulties in calculating gas saturation,four methods are proposed after study. Compared with practical production data, the method of combining gas saturation computation with selected Archie and Simandoux formulae is suitable for the field,which consistency of fluid property reaches to 88.89%. It is of great significance in guiding production in the area.