陕北甘谷驿油田东区延长组长6油层沉积相特征

甘谷驿油田东区长6油层砂体主要为灰色细粒长石砂岩,次为中—细粒长石砂岩,粒度概率曲线呈两段式,砂体内发育板状、槽状交错层理.结合甘谷驿油田上百口井的测井资料单井相分析及数十口井的粒度参数图件分析,认为甘谷驿油田东区长6油层砂体主要为湖泊三角洲平原的分流河道及三角洲前缘的水下分流河道沉积.绘制了长61、长62、长63油砂体的平面分布图,确定了水下分流河道的位置.由砂体展布图看出,自长64至长61期,三角洲前缘逐渐演化为三角洲平原,表明研究区湖盆逐渐萎缩,三角洲沉积范围不断扩大,属进积式三角洲沉积.

Characteristics of sedimentary facies of Chang 6 oil-bearing strata of Yanchang Formation in the east area of Ganguyi Oilfield,North Shaanxi

Lithology of chang 6 oil-bearing strata in the east area of Ganguyi oilfield is mainly fine feldspathic sandstone, and medium-fine feldspathic sandstone is secondary. Grain-size distribution probability curve of sand bodies is two segments, there are a lot of planar cross-bedding and trough cross-bedding in sand bodies. With above all being combined with the analyses of the log data of sedimentary facies of several hundreds of wells and the grain-size distribution figures of tens of wells, it can be concluded that the sand bodies of Chang 6 oil-bearing strata in the study area are mainly distributary channel deposits of delta plain facies and delta front facies. By drawing the distribution maps of the sand bodies, the location of the submerged distributary channel deposits are determined. From the distribution maps of the sand bodies, it can be found that Chang 6 oil-bearing strata evolves from delta front to delta plain from Chang 6~4 to Chang 6~1 period, which shows that lake basin in the area gradually decreases, delta deposits is increasing, and it is progradational deposit.