苏北盆地金湖凹陷阜宁组砂岩储层力学性质及影响因素

Mechanical properties and influencing factors of Funing Formation sandstone reservoir in Jinhu Sag,Subei Basin

储层岩石力学在油气田开发中具有关键作用。以苏北盆地金湖凹陷古近系阜宁组岩心为基础,综合采用岩石力学实验、X衍射、薄片分析、扫描电镜等方法,分析了阜宁组岩性、温度、流体及围压与砂岩力学性质的关系,探讨了各因素的影响机制。岩性是砂岩力学性质的决定性因素,砂岩力学性质与粒度、石英含量、黏土矿物含量、颗粒接触关系以及胶结物含量有关。温度对砂岩力学性质的影响具有分段性:25~100℃时,主导机制为矿物涨缩效应和层间水脱出;100~180℃时,主导机制为热开裂作用。随着油水比例的降低,砂岩力学参数发生规律性变化,砂岩强度弱化与孔隙流体压力、部分饱和作用以及化学作用有关。油田开发中人工措施对砂岩储层力学性质影响显著,在出砂预测和井壁稳定性分析中应引起重视。

Reservoir rock mechanics plays a key role in oil and gas field development.The relationship between lithology,temperature,fluid and confining pressure and the mechanical properties of sandstone reservoirs and the influence mechanism of each factor were discussed using rock mechanics tests,X-ray diffraction,cast thin section and scanning electron microscopy analyses of core samples from the Funing Formation in the Jinhu Sag of Subei Basin.Lithology is a decisive factor for the mechanical properties of sandstones,which are related to particle size,quartz content,clay mineral content,particle contact and cement content.The influence of temperature on the mechanical properties of sandstones is segmented.At 25-100℃,minerals expand and contract,while interlayer water escapes.At 100-180℃,thermal cracking is dominant.As the oil-water ratio decreases,the mechanical parameters of sandstones change regularly,and the weakening of sandstone strength is related to pore fluid pressure,partial saturation and chemical effects.Artificial measures in oilfield development have a significant impact on the mechanical properties of sandstone reservoirs,and attention should be paid on sand production prediction and wellbore stability analysis.