Development,sand control mechanism and hydrocarbon accumulation of beach-bar sandstone in a saline lake basin:A case from the Neogene of southwestern Qaidam Basin,NW China  

作　　者：WANG Yanqing LIU Zhanguo SONG Guangyong ZHU Chao LI Senming WU Yanxiong XIA Zhiyuan SHI Qi JIA Shenglong WANG Zhaobing WEI Xuebin 

机构地区：[1]PetroChina Hangzhou Institute of Geology,Hangzhou 310023,China [2]PetroChina Qinghai Oilfield Company,Dunhuang 736202,China

出　　处：《Petroleum Exploration and Development》2023年第4期851-864,共14页石油勘探与开发（英文版）

基　　金：Supported by the PetroChina Science and Technology Project (2021DJ0402,2021DJ0202)。

摘　　要：Based on the data of field outcrops,drilling cores,casting thin sections,well logging interpretation,oil/gas shows during drilling,and oil/gas testing results,and combined with modern salt-lake sediments in the Qinghai Lake,the Neogene saline lake beach-bars in southwestern Qaidam Basin are studied from the perspective of sedimentary characteristics,development patterns,sand control factors,and hydrocarbon accumulation characteristics.Beach-bar sand bodies are widely developed in the Neogene saline lake basin,and they are lithologically fine sandstone and siltstone,with wavy bedding,low-angle cross bedding,and lenticular-vein bedding.In view of spatial-temporal distribution,the beach-bar sand bodies are stacked in multiple stages vertically,migratory laterally,and extensive and continuous in NW-SE trending pattern in the plane.The stacking area of the Neogene beach-bar sandstone is predicted to be 3000 km^(2).The water salinity affects the sedimentation rate and offshore distance of beach-bar sandstone,and the debris input from the source area affects the scale and enrichment of beach-bar sandstone.The ancient landform controls the morphology and stacking style of beach-bar sandstone,and the northwest monsoon driving effect controls the long-axis extension direction of beach-bar sandstone.The beach-bars have a reservoir-forming feature of“one reservoir in one sand body”,with thick beach-bar sand bodies controlling the effective reservoir distribution and oil-source faults controlling the oil/gas migration and accumulation direction.Three favorable exploration target zones in Zhahaquan,Yingdong-eastern Wunan and Huatugou areas are proposed based on the analysis of reservoir-forming elements.

关 键 词：Qaidam Basin NEOGENE saline lake basin sedimentary characteristics beach-bar sand control mechanism reservoir characteristics 

分 类 号：P618.13[天文地球—矿床学]