伊拉克米桑油田群Mishrif組段碳酸鹽巖儲層特征及成因

張義楷，康　安，閔小剛，李志明，李偉超，高慧君

(中國海洋石油國際有限公司 中國海油伊拉克有限公司，北京　100028)

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張義楷，康安，閔小剛，李志明，李偉超，高慧君

(中國海洋石油國際有限公司 中國海油伊拉克有限公司，北京100028)

摘要：以巖心、錄井、測井、地震及相關生產(chǎn)資料為基礎，對伊拉克米桑(Missan)油田群Mishrif組段儲層特征及其成因進行分析。結(jié)果表明，Mishrif組段儲層沉積環(huán)境屬于碳酸鹽巖開闊臺地，發(fā)育有臺內(nèi)灘、臺內(nèi)礁和開闊潮下亞相。巖石類型主要有生物礁灰?guī)r、生屑顆?；?guī)r、生屑似球粒顆?；?guī)r及生屑似球粒泥粒灰?guī)r。儲集空間類型主要為原生粒間孔、次生粒間溶孔、鑄?？?、基質(zhì)微孔及少量小型溶蝕孔洞和微裂縫。受沉積作用和成巖作用控制，儲層橫向分布相對穩(wěn)定，但縱向物性變化較大、層內(nèi)非均質(zhì)性嚴重，是制約原油采出程度的關鍵因素。

關鍵詞：非均質(zhì)性；沉積相；成巖作用；碳酸鹽巖儲層；Mishrif組；米桑油田群; 伊拉克

1油田群概況及地質(zhì)背景

米桑(Missan)油田群位于伊拉克東南部米桑省[1]，毗鄰伊朗邊界，西北距巴格達約350 km，南距巴士拉約175 km(圖1)。油田群共包括3個油田，分別是Abu Ghirab，Buzurgan和Fauqi油田。受區(qū)域構造控制[2]，米桑構造區(qū)總體表現(xiàn)為北西—南東向的背斜構造，共發(fā)育東、西2個背斜構造帶。其中Abu Ghirab油田、Fauqi油田位于東背斜構造帶，Buzurgan油田位于西背斜構造帶。

圖1　伊拉克米桑油田群地理位置示意

2儲層特征

2.1巖石和儲集空間類型

儲層儲集空間類型主要有原生粒間孔、次生粒間溶孔、鑄?？住⒒|(zhì)微孔及少量小型溶蝕孔洞和微裂縫。其中生物礁灰?guī)r、生屑顆?；?guī)r和生屑似球粒顆?；?guī)r中主要發(fā)育原生粒間孔、次生粒間溶孔、粒內(nèi)孔和少量溶蝕孔洞。生屑似球粒泥?；?guī)r中主要發(fā)育鑄?？?、次生粒間溶孔和基質(zhì)微孔(圖3)。

圖2　伊拉克米桑油田群Mishrif組沉積與層序特征

圖3　伊拉克米桑油田群Mishrif組段儲層孔隙類型

Rud.厚殼蛤碎屑；For.有孔蟲屑；Ech.棘皮屑；Gpd.腹孔蟲屑；Cc.灰質(zhì)膠結(jié)；Ig.原生粒間孔；Dp.次生粒間溶孔；Pel.似球粒；

Mtx.基質(zhì)；Dol-C.白云質(zhì)膠結(jié)

2.2沉積相及其特征

圖4　伊拉克米桑油田群B-X1井Mishrif組

2.3儲層物性和非均質(zhì)性

表1　伊拉克米桑油田群Mishrif 組

注：表中分式含義為：最小值～最大值/平均值(樣品數(shù))。

圖5　伊拉克米桑油田群Buzurgan油田

圖6　伊拉克米桑油田群B-X2井Mishrif組段產(chǎn)液剖面

3儲層發(fā)育主控因素

3.1沉積作用

同時由于微地貌的起伏，在微地貌高地，為礁灘相沉積的有利區(qū)，發(fā)育物性相對較好的礁灰?guī)r或顆?；?guī)r儲層，而在相對低地則以灘間或開闊潮下環(huán)境的泥?；?guī)r發(fā)育為特征，儲層物性相對較差。

3.2成巖作用

3.3構造作用

構造作用對儲層的改造主要為微裂縫的發(fā)育[24-26]。雖然在研究區(qū)內(nèi)無明顯大斷裂發(fā)育，但在多口井的巖心中可觀察到微裂縫的發(fā)育，鏡下也可見局部發(fā)育開啟的有效微裂縫。這些微裂縫的發(fā)育對儲集空間的貢獻不大，其最為重要的作用是形成滲流通道，改善了局部儲層的物性。

4結(jié)論

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(編輯韓彧)

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

文章編號：1001-6112(2016)03-0360-06

doi：10.11781/sysydz201603360

收稿日期：2015-08-20；

修訂日期：2016-03-17。

作者簡介：張義楷(1980—)，男，博士研究生，工程師，從事油氣開發(fā)地質(zhì)研究。E-mail:zhangyk2@cnooc.com.cn。

基金項目：國家科技重大專項(2011ZX05030-005)資助。

中圖分類號：TE122.2

文獻標識碼：A