准噶尔盆地玛湖凹陷南缘风城组碱湖沉积环境致密储层成岩特征及成岩相  

Diagenetic facies of the Fengcheng Formation tight reservoir in the alkaline lake sedimentary environment,the southern margin of Mahu Sag,Junggar Basin

作　　者：张宗斌[1] 秦军[1] 巴忠臣[1] 黄文彪 韩梦芸 高宇慧[1] 吴栋 ZHANG Zongbin;QIN Jun;BA Zhongchen;HUANG Wenbiao;HAN Mengyun;GAO Yuhui;WU Dong(Research Institute of Exploration and Development,PetroChina Xinjiang Oilfield Company,Karamay 834000,China;School of Geosciences,China University of Petroleum(East China),Qingdao 266580,China;Fengcheng Oilfield Operation Area,PetroChina Xinjiang Oilfield Company,Karamay 834000,China)

机构地区：[1]中国石油新疆油田分公司勘探开发研究院,新疆克拉玛依834000 [2]中国石油大学(华东)地球科学与技术学院,山东青岛266580 [3]中国石油新疆油田分公司风城油田作业区,新疆克拉玛依834000

出　　处：《天然气地球科学》2024年第9期1557-1573,共17页Natural Gas Geoscience

基　　金：中国石油天然气股份公司前瞻性基础技术攻关项目“深层/超深层油气藏有效储层预测与高效井优化技术研究”(编号:2010DJ1003);中国石油天然气股份公司攻关性应用性科技专项“砾岩油藏规模增储上产与提高采收率关键技术研究”(编号:2023ZZ2)联合资助。

摘　　要：为探究准噶尔盆地玛湖凹陷南缘风城组碱湖沉积环境下的成岩作用特征及对储层的影响机制,明确优势成岩相的分布,在岩石学特征、孔隙类型、成岩作用以及成岩环境演变分析的基础上,定量表征了压实、胶结和溶蚀对储层改造强度,建立了成岩相划分方案,并基于单井取心层段的评价结果刻画了成岩相分布特征,阐释了成岩相分布影响机制。研究表明:研究区风城组储集空间呈现“基质孔隙为主、微裂缝为辅”的双重介质特征,其中粒内/粒间溶孔在基质孔隙中占主导地位。风城组历经碱性沉积环境和碱性—酸性—碱性的成岩环境演变,碱性沉积环境和早期碱性成岩阶段是粒间孔胶结损耗和火山物质水解以及斜长石钠长石化形成溶蚀孔的重要时期,建设性和破坏性成岩作用并存;中期成岩酸性环境下的扩孔作用使得溶蚀孔成为主要储集空间,致密化程度有所缓解;晚期碱性成岩环境下伴随着碱性矿物离子浓度再次增加,并开始在剩余粒间孔、溶蚀孔等储集空间内沉淀,储层致密化程度进一步提升。平面上,扇三角洲平原和前缘交界处胶结和溶蚀作用发育程度较弱,多发育压实相,平均孔隙度约为4.9%;扇三角洲内前缘至外前缘交界处溶蚀作用强于胶结,以胶结—溶蚀相为主,平均孔隙度约为6.6%,中部和南部断裂附近为溶蚀相,平均孔隙度高达9%;扇三角洲外前缘多发育溶蚀—胶结相,储层平均孔隙度约为3.1%。碱湖沉积背景下的碱性成岩作用对储层改造具有两面性,在酸性/碱性溶蚀控制下的胶结—溶蚀相和溶蚀相是该地区致密油聚集的有利场所,也是该地区单井高产的关键因素。In order to explore the diagenetic characteristics,influence mechanism and the distribution of dominant diagenetic facies of Fengcheng Formation in the southern margin of Mahu Sag,this paper quantitatively characterized the reservoir transformation intensity of compaction,cementation and dissolution on the basis of the analysis of petrological characteristics,pore types,diagenesis and diagenetic environment evolution,and established a diagenetic facies division scheme.Based on the evaluation results of single well coring interval,the characteristics of diagenetic facies distribution are described,and the influencing mechanism of diagenetic facies distribution is explained.The results show that the reservoir space of Fengcheng Formation in the study area is characterized by a dual medium of“matrix-pores dominated and micro-fractures supplemented”,in which the intra/intergranular dissolved pores are dominant in the matrix pores.The Fengcheng Formation has undergone the evolution of alkaline sedimentary environment and alkali-acid-alkaline diagenetic environment.The alkaline sedimentary and early alkaline diagenetic stages are the important periods for the loss of intergranular pore cementation,the hydrolysis of volcanic materials and the formation of solution pore by plagioclase albitization.The reaming in the acidic diagenetic environment in the middle stage makes the dissolution pore become the main reservoir space,and the densification degree is somewhat eased.In the late alkaline diagenetic environment,the concentration of alkaline mineral ions increases again and begins to precipitate in the remaining intergranular pores,solution pores,and other reservoir spaces,and the reservoir densification degree is further improved.The cementation and dissolution of fan delta plain and front junction in the study area were weak,and more compact phases developed,with an average porosity of about 4.9%.From the inner front of the fan delta to the junction of the outer front,the dissolution is stronger than the cementatio

关 键 词：致密储层 成岩作用 成岩相 风城组 玛湖凹陷 

分 类 号：TE122.23[石油与天然气工程—油气勘探]