致密砂岩气藏高温高压敏感性评价及机理探讨——以塔里木盆地B区块致密气藏为例

致密砂岩气藏储量丰富,因其低孔低渗、高毛细管力、高黏土矿物含量、孔喉细小、非均质严重等特点,导致其易受到敏感性损害。目前大多数敏感性评价研究针对常规中、低渗储层,对于致密砂岩气藏敏感性评价技术尚未成熟。文中以塔里木盆地B区块致密砂岩气藏为例,通过岩心流动实验,进行模拟地层条件下的高温高压敏感性评价。结果表明,该区块高温高压敏感性具有弱速敏损害、中等偏强水敏损害、中等偏弱盐敏损害、中偏弱碱敏损害、弱酸敏损害、强应力敏感损害的特点。进一步运用X射线衍射、扫描电镜、铸体薄片等测试手段,分析了B区块致密气藏矿物类型、体积分数、形态及分布特征,剖析了敏感性的成因——储层敏感性矿物及微观孔喉结构。

Sensitivity evaluation and mechanism of tight sandstone gas reservoir under high temperature and high pressure: a case study of tight gas reservoir in B Zone

The tight sandstone gas reservoir has abundant reserves,but it is susceptible to sensitivity damage because of poor porosity and permeability,high capillary forc e,high clay mineral content,tiny size of pore throats and severe heterogeneity.At present,most sensitivity evaluation studies are aimed at conventional medium and low permeability reservoirs,sensitivity evaluation of tight sandstone gas reservoir is not yet mature.This paper studies the tight sandstone gas reservoir in B Zone in the Tarim Basin.High temperature and high pressure sensitivity was evaluated by core flow experiment,and the result shows that this zone has the characteristics of low velocity sensitivity,medium to strong water sensitivity,medium to weak salt sensitivity,medium to weak alkali sensitivity,weak acid sensitivity and strong stress sensitivity.Combined with X-ray diffraction test,scanning electron microscopy and casting thin sections,this paper analyzes the type,content,shape and distribution characteristics of the minerals in the B Zone and concludes that the formation mechanism of sensitivity is influenced by sensitivity minerals and microscopic pore throat structure.