卫城油田卫2块沙三下亚段沉积相特征及演化规律研究

Sedimentary facies evolution in the lower submember of the third member of the Shahejie Formation in the Wei-2 block, Weicheng Oil Field, Dongpu depression

关键词:  卫城油田  沉积相  演化规律  湖平面变化

Key words:  Weicheng Oil Field  sedimentary facies  evolution  lake-level change

摘要:

随着卫城油田卫2块进入高含水开发后期,挖潜难度越来越大。为了更准确找准剩余油富集区,提高挖潜效果,本文应用现代沉积学理论,对研究区取芯井进行了详细的岩心观察和描述,综合运用钻井、录井、测井等资料,深入细致地研究了卫城油田卫2块沙三下亚段的沉积特征,发现下沙三下亚段为一套湖泊背景下的三角洲沉积体系,主要发育三角洲前缘亚相,并从中识别5种微相;论述了沙三下亚段沉积相的展布与演化规律,发现沙三下亚段沉积时期,东濮凹陷相对湖平面频繁变化,造成了砂体垂向上缺少完整的三角洲层序,浅水砂岩和深水泥岩互层出现,平面上沙三下亚段不同砂组甚至同一砂组不同小层的三角洲分布范围都有较大差异,三角洲的进积与退积交替出现。沉积相类型划分和演化规律研究为油田有效开发奠定了坚实的基础。

Abstract:

The delta front subfacies in the delta depositional system predominates in the lower submember of the third member of the Shahejie Formation in the Wei-2 block, Weicheng Oil Field, and may be subdivided into five sedimentary microfacies, including the subaqueous distributary channel, channel-mouth bar, interdistributary bay, overbank and sand sheet microfacies. During the deposition of the lower submember of the third member of the Shahejie Formation in the Wei-2 block, Weicheng Oil Field, frequent lake-level changes occurred in the Dongpu depression. Vertically, the sandstones display the incomplete delta sequences and the couplets of shallow-water sandstones and deep-water mudstones, and in a planar view, the alternation of progradation and retrogradation of the delta deposits. The results of research in this study may assist in the future development of the Weicheng Oil Field.