镇北长8_1储层微观孔喉结构及物性参数特征

Characteristics of microscopic pore structure and physical property parameter of Chang 8_1 oil reservoir in Zhenbei Area

采用铸体薄片、高压压汞、恒速压汞、稳定渗流、X衍射全岩分析、三轴压缩声发射等实验方法,对镇北地区长8_1致密砂岩储层储集空间、储层敏感性、岩石脆性等参数特征进行研究,结果表明,该地区储层储集空间以粒间孔和粒间溶孔为主,粒内溶孔(长石溶孔+岩屑溶孔)次之,部分地区存在晶间孔;储层发育偏粗态、偏细态、细态3种孔喉结构类型,其中以细态型孔隙结构为主;致密砂岩储层品质主要受喉道控制。长8_1致密砂岩储层具有应力敏感性较弱,脆性指数大,水平主应力差值小的特点,适合利用体积压裂技术进行开发。

The cast thin section an steady seepage, X-ray diffraction alysis, high-pressure mercury, constant-speed mercury porosimetry, and acoustic emission of rocks under triaxial compression methods are used to experimentally investigate the reservoir space and physical property parameters of the Chang 81 tight sandstone reservoir in the Zhenbei Area. The results show that the reservoir space is dominated by intergranular pore and intergranular dissolution pore, followed by intragranular dissolution pore （feldspar dissolved pore and lithic dissolved pore）, and only few areas exhibit intercrystalline pore. Three types of pore structures are observed, namely less wide form, rather narrow form and narrow form. The quality of tight sandstone reservoir is mainly controlled by throat. The results show that the research area has characteristics of the low stress sensitivity, high brittleness index and small horizontal principal stress difference. It＇ s suitable for SRV fracturing.