准噶尔盆地玛北地区三叠系百口泉组优质储层成因分析

Genetic Analysis of the High Quality Reservoir of Triassic Baikouquan Formation in Mabei Region,Junggar Basin

勘探实践表明,准噶尔盆地西北缘玛北地区三叠系百口泉组存在大量优质储层,然而其成因需要进一步研究。岩石学特征、物性特征、沉积环境特征、成岩作用特征的研究表明:玛北地区三叠系百口泉组储层以粗碎屑的砂砾岩为主,细碎屑的砂岩类储层含量较少,储层平均孔隙度主要分布于7%~9%之间,平均渗透率主要分布于0.9×10-3μm2~1.4×10-3μm2之间。储层主要发育于扇三角洲前缘水下分流河道及扇三角洲平原分流河道微相,在构造坡折带的影响下,经过水体较长时间淘洗的扇三角洲前缘水下分流河道砂砾岩储层物性最好,往往成为该区优质储层,扇三角洲平原分流河道砂砾岩储层的物性次之。压实作用造成了泥质杂基含量较高的砂砾岩储层物性的不可逆降低,成岩早期适量的胶结物提供了支撑颗粒骨架,可以抵御压实作用对储层物性的影响,但成岩晚期大量的胶结物可以阻塞孔隙,对储层具有不利的影响,长石颗粒及沸石类胶结物的溶蚀作用对储层物性的改善具有积极意义。

The petroleum exploration of Junggar Basin shows that a mass of high quality reservoirs developed in Triassic Baikouquan Formation of Mabei region,while the genesis of high quality reservoir still needs further research. The characteristics of reservoir petrology,physical property,sedimentary environment and diagenesis indicate that reservoir of Triassic Baikouquan Formation in Mabei area is mainly composed of coarse clastic glutenite. The fine grained clastic sandstone reservoirs less developed,reservoirs average porosity is mainly between 7% and 9%,and average permeability is 0.9×10-3μm2and 1.4×10-3μm2; Fan-delta front subaqueous distributary channel and fan-delta plain distributary channel are favorable reservoirs which are affected by structural slop-break zone,due to long time water washing,Fan-delta front subaqueous distributary channel glutenite reservoir property is best and then Fan-delta plain distributary channel sand body. Compaction causes higher argillaceous matrix glutenite reservoir property irreversibly decrease,proper eogenetic cement provide the supported grain skeleton,which can resist compaction effect on reservoir physical properties,but late diagenesis lots of cement can block the pore and bad to reservoirs. Whereas the dissolution of feldspar particles and zeolite cement has positive significance on the improvement of the reservoir property.