海相油气地质2025，Vol.30Issue(5)：471-480,10.DOI:10.3969/j.issn.1672-9854.2025.05.008
海陆过渡带平缓斜坡背景下复杂岩性发育的控制机制——以伊拉克B油田Asmari组为例
Controlling mechanisms of complex lithology development in a gentle slope marine-continental transitional setting:a case study of the Asmari Formation in Iraq B Oilfield
摘要
Abstract
The Asmari Formation in Iraq B Oilfield was deposited in a remnant ocean basin environment formed during the closure process of the Neo-Tethys Ocean.Influenced by the intermittent uplift of the Arabian Shield from the Oligocene to Miocene,the study area developed a multi-stage terrigenous clastic supply system.Under the depositional background of a gentle slope,frequent sea-level fluctuations have led to complex mixed sedimentary characteristics of sandstone,dolomite,limestone,and mixed rocks in vertical and planar distributions,whose lithological distribution laws remain to be further clarified.This study takes Iraq B Oilfield as the research object,and systematically reveals the main controlling factors of complex lithology development under the gentle slope background through detailed core observation,thin-section microscopic analysis,and comprehensive interpretation of drilling and logging data.The research has achieved the following understandings:(1)The lithologies of the Asmari Formation can be scientifically classified into three major categories:carbonate rocks,mixed rocks,and terrigenous clastic rocks.Among them,mixed rocks are further subdivided into 8 types based on the 50%ternary classification nomenclature;seven typical lithofacies combination sequences are identified through the coupling analysis of petrological characteristics and logging responses.(2)The spatial distribution of lithofacies shows significant zonation:the northwestern and southeastern regions of the study area are dominated by carbonate facies,the proportion of clastic facies in the central part increases significantly,and the mixed rock facies account for a large proportion in the remaining transition zones.(3)The paleogeomorphology of the study area presents a gentle slope pattern of"low in the northwest and southeast parts and high in the central part".The comprehensive tectonic-sedimentary analysis shows that terrigenous clastic sediments are mainly developed in the paleo-uplift area,carbonate sediments are developed in the paleo-depression area,and mixed sediments are dominant in the transitional slope zone.Finally,a development model of complex lithology controlled by three factors of"paleogeomorphic form—sea-level fluctuation—material source supply"under the gentle slope background is established.关键词
复杂岩性/岩性发育模式/平缓斜坡/海陆过渡/Asmari组/伊拉克Key words
complex lithology/lithological development pattern/marine-continental transition/Asmari Formation/Iraq分类
石油、天然气工程引用本文复制引用
童凯军,李宗泽,曹树春,唐嘉伟,刘毅龙,刘四兵,范云杰,伏美燕..海陆过渡带平缓斜坡背景下复杂岩性发育的控制机制——以伊拉克B油田Asmari组为例[J].海相油气地质,2025,30(5):471-480,10.基金项目
本文受中国海洋石油有限公司"十四五"重大科技项目"复杂岩性碳酸盐岩储层分类及精细表征"(编号:KJGG2022-0905)、国家自然科学基金"四川盆地中西部中层—浅层致密砂岩流体跨层混合示踪、过程重建及成储-成藏效应"(编号:42472180)和"川西须家河组深层致密砂岩流体-岩石相互作用及储层响应机制"(编号:41972158)联合资助 （编号:KJGG2022-0905）
