中东地区R油田Mishrif组储层主控因素及其分布规律
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摘要
Mishrif组作为伊拉克东南部R油田重要的油气产层之一,储层成因及分布规律认识不清制约着该层系后备油气资源开发利用成效。本文综合岩石薄片、岩心物性、常规及特殊测井数据等资料,分别分析了沉积、成岩要素对Mishrif组储层的控制作用,认为R油田Mishrif组生物礁滩、滩前、滩后、潟湖相皆不同程度发育储层:规模性优质储层发育在生物礁滩环境,强烈溶蚀作用及弱胶结作用是重要成储条件,储集空间以溶孔、粒间溶孔及铸模孔为主;低能相带储层形成于弱胶结作用环境,未被胶结物充填保留的生屑颗粒间溶孔、粒内孔是储层发育的基础。对比不同类型储层岩电响应特征,刻画并描述了Mishrif组优质储层的分布规律:Mishrif组下部(MB段)生物礁滩储层物性优于上部(MA段)同类储层,优质储层位于准层序上部,受大气淡水溶蚀作用改造显著;滩后、潟湖相中等品质储层叠置发育在生物礁滩型储层上部,且由于差异胶结作用的影响使之在横向及垂向上表现出明显的非均质性。
The Mishrif Formation (Upper Cretaceous) is an important carbonate reservoir in Middle East,and the knowledge of formation and distribution of Mishrif carbonate reservoir has important significance for efficient exploration and development of hydrocarbon resources. Based on the comprehensive utilization of thin sections,petrophysical data,conventional logging data and imaging and NMR logging data of Mishrif Formation in R oilfield,southeast Iraq,we comparatively analysed the sedimentary and diagenesis factors of Mishrif carbonate ramp reservoirs,and defined well logging responses and described the distribution of various reservoirs. The reservoirs developed in reef \ bioclastic shoal,back-shoal,fore-shoal and lagoon facie. The high-quality reservoirs are mostly concentrated in high energy reef \ bioclastic shoal settings where strong corrosion and weak cementation are the important diagenetic conditions. The low-energy facies reservoir formed in weak cementation environment, and the retained inter-granular (dissolved) pores and intra-granular pores which had not been filled with cements are the foundation for quality reservoir. The filling of micrite and various cements resulted in inferior reservoir quality with limited pore space. The qualities of reef \ bioclastic shoal reservoir in the lower Mishrif formation (MB) are better than those in the upper Mishrif formation (MA). The high quality reservoir developed in the upper of para-sequence,which was intensively affected by meteoric dissolution. The moderate quality reservoir formed in back-shoal and lagoon facies lies on the top of the reservoir developed in bioclastic/reef facies,which show progradational sequence along with relative sea level continuously declining.Since different degree of cementation, reservoirs with various petrophysical conditions vertically distributed with each other.
The Mishrif Formation (Upper Cretaceous) is an important carbonate reservoir in Middle East,and the knowledge of formation and distribution of Mishrif carbonate reservoir has important significance for efficient exploration and development of hydrocarbon resources. Based on the comprehensive utilization of thin sections,petrophysical data,conventional logging data and imaging and NMR logging data of Mishrif Formation in R oilfield,southeast Iraq,we comparatively analysed the sedimentary and diagenesis factors of Mishrif carbonate ramp reservoirs,and defined well logging responses and described the distribution of various reservoirs. The reservoirs developed in reef \ bioclastic shoal,back-shoal,fore-shoal and lagoon facie. The high-quality reservoirs are mostly concentrated in high energy reef \ bioclastic shoal settings where strong corrosion and weak cementation are the important diagenetic conditions. The low-energy facies reservoir formed in weak cementation environment, and the retained inter-granular (dissolved) pores and intra-granular pores which had not been filled with cements are the foundation for quality reservoir. The filling of micrite and various cements resulted in inferior reservoir quality with limited pore space. The qualities of reef \ bioclastic shoal reservoir in the lower Mishrif formation (MB) are better than those in the upper Mishrif formation (MA). The high quality reservoir developed in the upper of para-sequence,which was intensively affected by meteoric dissolution. The moderate quality reservoir formed in back-shoal and lagoon facies lies on the top of the reservoir developed in bioclastic/reef facies,which show progradational sequence along with relative sea level continuously declining.Since different degree of cementation, reservoirs with various petrophysical conditions vertically distributed with each other.
引文
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[9]王君,郭睿,赵丽敏,等.颗粒滩储集层地质特征及主控因素-以伊拉克哈法亚油田白垩系Mishrif组为例[J].石油勘探与开发,2016,43(3):1-11.
[10]王昱翔,周文,郭睿,等.伊拉克哈勒法耶油田Mishrif组滩相储层特征及其成因分析[J].吉林大学学报(地球科学版),2017,47(4):1007-1020.
[11]Moutaz A D,Jassim A J,Saad A J.Depositional environments and porosity distribution in regressive limestone reservoirs of the Mishrif Formation,Southern Iraq[J].Arab Journal of Geoscience,2010,3(1):67-78.
[12]Mahdi T A,Aqrawi A A M.Sequence stratigraphic analysis of the Mid-Cretaceous Mishrif Formation,Southern Mesopotamian Basin,Iraq[J].Journal of Petroleum Geology,2014,37(3):287-312.
[2]白国平.世界碳酸盐岩大油气田分布特征[J].古地理学报,2006,8(2):241-250.
[3]Ehrenberg S N,Aqrawi A A M,Nadeau P H.An overview of reservoir quality in producing Cretaceous strata of the Middle East[J].Petroleum Geoscience,2008,14(4):307-318.
[4]Aqrawi A A M,Thehni G A,Sherwani G H,et al.MidCretaceous rudist-bearing carbonates of the Mishrif Formation:an important reservoir sequence in the Mesopotamian Basin,Iraq[J].Journal of Petroleum Geology,1998,21(1):57-82.
[5]高计县,田昌炳,张为民,等.波斯湾盆地中白垩统Mishrif组碳酸盐岩储层特征及其发育模式[J].地质科学,2013,48(1):304-316.
[6]邓亚,郭睿,田中元,等.碳酸盐岩储集层隔夹层地质特征及成因-以伊拉克西古尔纳油田白垩系Mishrif组为例[J].石油勘探与开发,2016,43(1):136-144.
[7]李扬,刘波,田昌炳,等.伊拉克Y油田上白垩统Mishrif组碳酸盐岩储层及其测井响应特征[J].油气地质与采收率,2016,23(6):8-15.
[8]张义楷,康安,闵小刚,等.伊拉克米桑油田群Mishrif组MB 2~1段碳酸盐岩储层特征及成因[J].石油实验地质,2016,38(3):360-365.
[9]王君,郭睿,赵丽敏,等.颗粒滩储集层地质特征及主控因素-以伊拉克哈法亚油田白垩系Mishrif组为例[J].石油勘探与开发,2016,43(3):1-11.
[10]王昱翔,周文,郭睿,等.伊拉克哈勒法耶油田Mishrif组滩相储层特征及其成因分析[J].吉林大学学报(地球科学版),2017,47(4):1007-1020.
[11]Moutaz A D,Jassim A J,Saad A J.Depositional environments and porosity distribution in regressive limestone reservoirs of the Mishrif Formation,Southern Iraq[J].Arab Journal of Geoscience,2010,3(1):67-78.
[12]Mahdi T A,Aqrawi A A M.Sequence stratigraphic analysis of the Mid-Cretaceous Mishrif Formation,Southern Mesopotamian Basin,Iraq[J].Journal of Petroleum Geology,2014,37(3):287-312.