摘要
通过大量的岩心观察,结合测井和化验分析等资料,恢复了长81油层沉积期的水深及沉积环境,认为鄂尔多斯盆地延长组长81油层属于典型的浅水三角洲沉积,其沉积特征与一般三角洲具有明显的差异,通过分析浅水三角洲的沉积特征和砂体分布规律,确定了3种不同的浅水三角洲类型,即顺直型分流河道三角洲,树枝型分流河道三角洲和分流砂坝型三角洲。顺直型分流河道三角洲主要分布在西北沉积体系,河道稳定持续,分流河道砂体顺物源方向呈带状向湖盆中心延伸,单层厚度大,连续性好;树枝型分流河道三角洲主要分布在西南沉积体系,河道摆动较大,分流河道多出现分支,砂体顺物源方向呈树枝和鸟足状向湖盆中心延伸,单层厚度较西北体系相对较小,连续性较好;分流砂坝型三角洲主要分布在东北沉积体系,河道横向摆动较大,砂体横向连片,顺砂体方向连续性相对较差,单层厚度较薄,泥质夹层比较发育,砂体形态在平面上呈朵状分布。
Though core observations and data analysis of well logging and laboratory test,water depth and depositional environment of Chang 81 period were restored,it was considered that Chang 81 oil reservoir of Yanchang Formation in Ordos Basin belonged to classical shallow water delta deposition,its characteristics were apparently different from that of normal delta deposition.By analyzing characters of sedimentation and sandbody distribution characteristics of shallow water delta,three types of shallow water deltas were determined,such as straight distributive channel,branched distributive channel and distributary bars.The distributive channel delta was mainly distributed in the northwest depositional system,river channel was sustainably stable,sandbody of distributive channel was extended along the direction of central-basin with huge thickness is single layer and good continuity.A branched distributive channel delta was mainly distributed in the southwest depositional system with river channel alternating seriously,the most of the distributive channel presented many branches,where sandbody of distributive channel was extended as arborescence and pedate along the provenance to the central-basin,sandbody thickness of single layer was thinner than that in northwest depositional system with better continuity.The delta of distributary bar is mainly distributed in the northeast depositional system with serious river channel alternation in horizontal direction,and sandbody is continuously in horizontal direction,continuity is poorer along direction of provenance with thinner sand body thickness of single layer,muddy intercalation is well grown,sand body shapes are distributed in lobate.
出处
《石油天然气学报》
CAS
CSCD
2013年第6期10-16,4,共7页
Journal of Oil and Gas Technology
基金
国家科技重大专项(2011ZX05044
2011ZX05001)
关键词
鄂尔多斯盆地
长81油层
浅水三角洲
沉积类型
沉积模式
Ordos Basin
Chang 81 Oil Formation
shallow water delta
sedimentation type
depositional mode
