摘要
准噶尔盆地玛湖凹陷二叠系风城组陆相页岩油储层埋深超过4500 m,天然裂缝作为重要的储集空间和渗流通道,对页岩油的富集和高产至关重要。尽管前人对风城组裂缝进行了表征,但是在裂缝有效性评价方面缺少系统研究,严重制约了玛湖凹陷页岩油下一步的勘探开发。基于微电阻率成像测井资料,对研究区天然裂缝的发育规律和有效性进行了系统研究。研究表明:准噶尔盆地玛湖凹陷风城组陆相页岩油储层天然裂缝有穿层裂缝和层内裂缝两类。穿层裂缝规模较大,裂缝高度通常超过米级,受断层的控制;层内裂缝发育在脆性地层内,裂缝高度受岩层厚度的控制,多小于50 cm。垂向上单井裂缝发育程度与脆性矿物含量呈正相关关系;平面上随距断层距离的增加,裂缝发育程度逐渐降低。不同方位裂缝的充填情况差异较大,北西-南东向裂缝多数未被矿物充填,有效性好。随着埋深增加,裂缝开度整体呈现减小的趋势。评价认为北东东-南西西向裂缝的开度最大,有效性最好。
The lacustrine shale oil reservoirs of the Fengcheng Formation in the Mahu Sag,Junggar Basin have burial depths exceeding 4500 m.Natural fractures in these reservoirs,serving as important storage spaces and seepage channels,are critical to the enrichment and high yield of shale oil.There is a lack of systematic study on their effectiveness evaluation despite existing characterization of these fractures in previous works,severely restricting the further exploration and exploitation of shale oil in the Mahu Sag.Given this,we conduct a systematic study on the distribution patterns and effectiveness evaluation of natural fractures in the study area using formation microresistivity imaging(FMI)logs.The results indicate that there exist two types of natural fractures in the lacustrine shale oil reservoirs in the study area:cross-layer fractures and intralayer fractures.The cross-layer fractures are characterized by a large scale,with heights generally reaching up to several meters or above,and their distribution is governed by faulting.The intralayer fractures are found within brittle beds,and their heights are limited by the thickness of rock layers,largely less than 50 cm.Vertically,the fracture density in a single well is positively correlated with the brittle mineral content.Laterally,the fracture density gradually decreases with increasing distance from faults.Fractures with different orientations exhibit greatly varying degrees of filling.The NW-SE-trending fractures,among others,are mostly not filled with minerals,thus boasting high effectiveness.As the burial depth increases,fracture apertures generally trend downward.The evaluation results reveal that the NEE-SWW-trending fractures exhibit the largest aperture and,accordingly,the highest effectiveness.
作者
杜晓宇
金之钧
曾联波
刘国平
杨森
梁新平
陆国青
DU Xiaoyu;JIN Zhijun;ZENG Lianbo;LIU Guoping;YANG Sen;LIANG Xinping;LU Guoqing(Institute of Energy,Peking University,Beijing 100871,China;State Key Laboratory of Shale Oil and Gas Enrichment Mechanismsand Effective Development,Beijing 100083,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;Research Institute of Exploration and Development,PetroChina Xinjiang Oilfield Company,Karamay,Xinjiang 834000,China)
出处
《石油与天然气地质》
EI
CAS
CSCD
北大核心
2024年第3期852-865,共14页
Oil & Gas Geology
基金
国家自然科学基金项目(42090025,42302148)
中国石油科技创新基金项目(2023DQ02-0103)。
关键词
有效性
成像测井
天然裂缝
页岩油
风城组
玛湖凹陷
准噶尔盆地
effectiveness
formation microresistivity imaging logging
natural fracture
shale oil
Fengcheng Formation
Mahu Sag
Junggar Basin
作者简介
第一作者:杜晓宇(1995—),男,博士研究生,页岩油储层天然裂缝。E-mail:duxiaoyu2016@163.com。;通信作者:金之钧(1957—),男,中国科学院院士,石油地质理论和能源战略研究。E-mail:jinzj1957@pku.edu.cn。
