伊拉克米桑油田群Mishrif组段碳酸盐岩储层特征及成因

张义楷，康　安，闵小刚，李志明，李伟超，高慧君

(中国海洋石油国际有限公司 中国海油伊拉克有限公司，北京　100028)



张义楷，康安，闵小刚，李志明，李伟超，高慧君

(中国海洋石油国际有限公司 中国海油伊拉克有限公司，北京100028)

摘要：以岩心、录井、测井、地震及相关生产资料为基础，对伊拉克米桑(Missan)油田群Mishrif组段储层特征及其成因进行分析。结果表明，Mishrif组段储层沉积环境属于碳酸盐岩开阔台地，发育有台内滩、台内礁和开阔潮下亚相。岩石类型主要有生物礁灰岩、生屑颗粒灰岩、生屑似球粒颗粒灰岩及生屑似球粒泥粒灰岩。储集空间类型主要为原生粒间孔、次生粒间溶孔、铸模孔、基质微孔及少量小型溶蚀孔洞和微裂缝。受沉积作用和成岩作用控制，储层横向分布相对稳定，但纵向物性变化较大、层内非均质性严重，是制约原油采出程度的关键因素。

关键词：非均质性；沉积相；成岩作用；碳酸盐岩储层；Mishrif组；米桑油田群; 伊拉克

1油田群概况及地质背景

米桑(Missan)油田群位于伊拉克东南部米桑省[1]，毗邻伊朗边界，西北距巴格达约350 km，南距巴士拉约175 km(图1)。油田群共包括3个油田，分别是Abu Ghirab，Buzurgan和Fauqi油田。受区域构造控制[2]，米桑构造区总体表现为北西—南东向的背斜构造，共发育东、西2个背斜构造带。其中Abu Ghirab油田、Fauqi油田位于东背斜构造带，Buzurgan油田位于西背斜构造带。

图1　伊拉克米桑油田群地理位置示意

2储层特征

2.1岩石和储集空间类型

储层储集空间类型主要有原生粒间孔、次生粒间溶孔、铸模孔、基质微孔及少量小型溶蚀孔洞和微裂缝。其中生物礁灰岩、生屑颗粒灰岩和生屑似球粒颗粒灰岩中主要发育原生粒间孔、次生粒间溶孔、粒内孔和少量溶蚀孔洞。生屑似球粒泥粒灰岩中主要发育铸模孔、次生粒间溶孔和基质微孔(图3)。

图2　伊拉克米桑油田群Mishrif组沉积与层序特征

图3　伊拉克米桑油田群Mishrif组段储层孔隙类型

Rud.厚壳蛤碎屑；For.有孔虫屑；Ech.棘皮屑；Gpd.腹孔虫屑；Cc.灰质胶结；Ig.原生粒间孔；Dp.次生粒间溶孔；Pel.似球粒；

Mtx.基质；Dol-C.白云质胶结

2.2沉积相及其特征

图4　伊拉克米桑油田群B-X1井Mishrif组

2.3储层物性和非均质性

表1　伊拉克米桑油田群Mishrif 组

注：表中分式含义为：最小值～最大值/平均值(样品数)。

图5　伊拉克米桑油田群Buzurgan油田

图6　伊拉克米桑油田群B-X2井Mishrif组段产液剖面

3储层发育主控因素

3.1沉积作用

同时由于微地貌的起伏，在微地貌高地，为礁滩相沉积的有利区，发育物性相对较好的礁灰岩或颗粒灰岩储层，而在相对低地则以滩间或开阔潮下环境的泥粒灰岩发育为特征，储层物性相对较差。

3.2成岩作用

3.3构造作用

构造作用对储层的改造主要为微裂缝的发育[24-26]。虽然在研究区内无明显大断裂发育，但在多口井的岩心中可观察到微裂缝的发育，镜下也可见局部发育开启的有效微裂缝。这些微裂缝的发育对储集空间的贡献不大，其最为重要的作用是形成渗流通道，改善了局部储层的物性。

4结论

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(编辑韩彧)

Zhang Yikai, Kang An, Min Xiaogang, Li Zhiming, Li Weichao, Gao Huijun

(CNOOCIraqLimited,CNOOCInternationalLimited,Beijing100028,China)

Abstract:The characteristics and genesis of carbonate reservoirs in the Mishrif member in the Missan oil fields were studied based on core, well logging, seismic and production data. The reservoirs were mainly deposited in a carbonate open platform sedimentary environment, and developed several subfacies such as bioclastic shoals, bioherms and open subtidal deposits. Rudist grainstones, skeletal grainstones, skeletal peloidal grainstones and skeletal peloidal packstones were found. Primary intergranular pores, secondary dissolution pores, mouldic pores, micro-pores associated with matrix, a small quantity of micro-vuggy and micro-fractures provided space for hydrocarbon accumulation. Controlled by deposition and diagenesis, reservoir distribution was similar laterally, but varied obviously vertically and showed a strong heterogeneity, which restricted oil development.

Keywords:heterogeneity; sedimentary facies; diagenesis; carbonate reservoir; Mishrif Formation; Missan oil fields; Iraq

文章编号：1001-6112(2016)03-0360-06

doi：10.11781/sysydz201603360

收稿日期：2015-08-20；

修订日期：2016-03-17。

作者简介：张义楷(1980—)，男，博士研究生，工程师，从事油气开发地质研究。E-mail:zhangyk2@cnooc.com.cn。

基金项目：国家科技重大专项(2011ZX05030-005)资助。

中图分类号：TE122.2

文献标识码：A