中国地质调查2026，Vol.13Issue(4)：23-32,10.DOI:10.19388/j.zgdzdc.2026.242
赤峰地区平庄凹陷沙海组重力流沉积特征及油气地质意义
Sedimentary characteristics and petroleum geological significance of gravity flow deposits in Shahai Formation of Pingzhuang sag in Chifeng area
摘要
Abstract
As an important sedimentary phenomenon in(semi-deep)deep-marine and deep-lacustrine envi-ronment,the gravity flow sedimentation is widely developed in the inland lake basins of China.The accurate iden-tification of gravity flow deposits is of great significance for both reconstructing paleo-depositional environment and guiding hydrocarbon exploration.Pingzhuang sag in Chifeng area of Inner Mongolia was selected as the re-search object,and diverse datasets were comprehensively utilized,including drilling core observation,thin section identification,grain size analysis,and logging data.The sedimentary features and types,the controlling factors of deep-water gravity flow deposit in the Lower Cretaceous Shahai Formation of Pingzhuang sag were studied.The results showed that the gravity flow deposit of the Lower Cretaceous Shahai Formation of Pingzhuang sag was main-ly lithic arkose and the grain-size probability cumulative curve was a low-slope two-segment pattern and a broad and gentle upward arch.The gravity-flow sediments in the study area mainly consisted of three types,slump flows,debris flow and turbidite flow.The slump flow was primarily characterized by convolute bedding,sandy parcel in mud,intercalation of deformed and undeformed strata,sharp contact,mud parcel in sandy and floating clasts.Sandy debris flow was widely distributed in debris flow deposits,which was characterized by sharp contact,mudstone tear blocks,and flame-like structures.The distribution of muddy debris flow deposit was rel-atively scarce,with the main characteristics being sandy clumps and mudstone with irregularly distributed sand-stone.Turbidite flow deposit was primarily characterized by incomplete Bouma sequence with normal graded bed-ding and a scoured bedding surface at the bottom.The abundant oil and gas indications have been revealed in the deep-water gravity flow sediments by MPD1 drilling.And logging data shows gas anomalies in 2 layers,with a maximum total hydrocarbon content of 16.55%.Core immersion revealed active bead-like bubbles.Well log-ging interpretation indicated a poor gas-bearing formation and a suspicious oil-bearing formation,with thickness of 10.2 m and 6.4 m,respectively.Comprehensive studies indicated that oil gas generation and migration oc-curred in Pingzhuang sag,with certain reservoir and preservation conditions,demonstrating certain oil gas explora-tion prospects.This study could provide references for subsequent oil gas exploration deployment in small to medi-um sized continental lacustrine basins.关键词
重力流沉积/沉积特征/沙海组/平庄凹陷/赤峰地区Key words
gravity flow sedimentation/sedimentary features/Shahai Formation/Pingzhuang sag/Chifeng area分类
天文与地球科学引用本文复制引用
王建伟,王丹丹,尹敏,张交东,张健,曾秋楠..赤峰地区平庄凹陷沙海组重力流沉积特征及油气地质意义[J].中国地质调查,2026,13(4):23-32,10.基金项目
中国地质调查局"赤峰盆地油气资源调查评价(编号:DD20240200404)"和中石油冀东油田分公司"赤峰、滦平地区中生界石油地质特征研究及油气远景评价(编号:JDYT-2025-JS-1481)"项目联合资助. （编号:DD20240200404）
