鄂尔多斯盆地东南部长6段重力流沉积类型及成因

Sedimentary types and genesis of gravity flow in Chang 6 Member of southeastern Ordos Basin

李晓路,马芳侠,贺永红,陈义国,李广涛

LI Xiaolu, MA Fangxia, HE Yonghong, CHEN Yiguo, LI Guangtao

陕西延长石油（集团）有限责任公司研究院，陕西 西安 710065

Research Institute of Shaanxi Yanchang Petroleum (Group) Co., Ltd., Xi′an 710065, China

针对鄂尔多斯盆地东南部长6段重力流沉积砂体平面展布规律及沉积成因不明等问题，利用岩心资料和钻测井数据，对长6段重力流沉积类型、分布规律、沉积过程进行了系统分析。研究表明：研究区主要发育滑塌流、砂质碎屑流、浊流3种沉积类型，可识别出扇根和扇中2类亚相。扇根亚相主要分布在研究区北部，呈孤立的条带状；扇中亚相发育范围广泛，连续性较好。依据研究区地质条件分析，认为重力流沉积形成过程可划分为滑塌、砂质碎屑流沉积、浊流沉积3个阶段。东南部长6段重力流沉积砂体毗邻长7段优质烃源岩区，具有优越的成藏条件，其中扇中区域以砂质碎屑流沉积为主，砂体厚度大、物性好、含油饱和度高，生储盖组合配置关系较好，是研究区重要的石油勘探目标。

Aiming at the problems of the plane distribution law of gravity flow sedimentary sand bodies of Chang 6 Member in the southeast of Ordos Basin and the unclear sedimentary genesis, using abundant core and drilling-logging data, the Chang 6 Member gravity flow sedimentation type, distribution law and deposition process were analyzed. Research shows that the study area mainly develops three types of sedimentary types: slump flow, sandy clastic flow, and turbidity current. Two subfacies types of fan root and mid-fan can be identified. Fan root subfacies are mainly distributed in the northern part of the study area and are isolated strips. The mid-fan has a wide range of development and good continuity. Based on the analysis of the geological conditions in the study area, it is believed that the gravity flow deposition process can be divided into three stages: slump stage, sandy debris flow stage, and turbidity current stage. The gravity flow sedimentary sand body of Chang 6 Member in the southeast is adjacent to the high-quality source rock area of Chang 7 Member, which has excellent reservoir forming conditions. The mid-fan area is dominated by sandy clastic flow sand bodies, with large thickness, good physical properties, high oil saturation, and has a good source-reservoir-cap assemblage relationship, which is an important oil exploration target in the study area.

10.6056/dkyqt202201007