摘要： 作为四川盆地超深层油气资源的主力产层之一,灯影组超深层碳酸盐岩储集层发育特征及其控制因素亟待进一步厘清。选取四川盆地内最新勘探突破的蓬莱地区灯影组灯四段超深层白云岩为主要研究对象,在野外露头、钻井岩心、显微薄片、阴极发光、扫描电镜及物性测试数据等资料的基础上,开展了储集层特征及主控因素等方面的研究。结果表明: (1)蓬莱地区灯四段储集岩主要包括凝块石白云岩、叠层石白云岩、泡沫绵层白云岩和砂屑白云岩; 储集空间主要包括砂屑白云岩的晶间孔、晶间溶孔和溶洞,凝块石白云岩、叠层石白云岩和泡沫绵层白云岩的原生格架孔洞和后期溶蚀作用形成的溶蚀孔缝等。(2)凝块石白云岩和叠层石白云岩多发育孔洞缝型和孔洞型储集层,均具有较好的物性,孔隙度能达到4%以上,但前者平均渗透率可达2.43×10^-3 μm²,后者仅为0.35×10^-3 μm²。(3)综合分析成岩演化史,认为灯四段储集层先后经历了沉积—准同生阶段、表生阶段、浅—中埋藏阶段和深层—超深层埋藏阶段的成岩改造。(4)蓬莱地区灯四段储集层发育具有自台地内部向台地边缘逐渐减弱的分布规律,总体上显示“相—断裂—溶蚀”三元综合成储模式。本研究明确了四川盆地蓬莱地区超深层白云岩储集层的特征及主控因素,可为后续超深层油气资源勘探开发提供理论基础。

关键词: 超深层碳酸盐岩, 储集层特征, 主控因素, 灯影组, 蓬莱地区, 四川盆地

Abstract: The Dengying carbonate reservoirs, as one of the primary producing units of ultra-deep hydrocarbon resources in the Sichuan Basin,is required for further studies on their characteristics and controlling factors. This paper focuses on the ultra-deep dolomite of the fourth member of the Dengying Formation in the recently explored Penglai area of the Sichuan Basin. The study examines the reservoir's petrological characteristics,pore spaces,classification of reservoir types,physical properties,diagenetic evolution,and the main controlling factors of the reservoirs. The analysis is based on field outcrop profiles,drilling cores,microsections,cathodoluminescence(CL)imaging,scanning electron microscopy (SEM) data,and physical property test results. The findings are as follows: (1)The primary lithologies of the fourth member of the Dengying Formation in the Penglai area include dolo-thrombolite,dolo-stromatolite,dolo-spongiomicrobialite,and sand-debris dolomite. The main reservoir spaces consist of primary framework pores and secondary dissolution pores formed by subsequent dissolution processes. (2)Fractured reservoirs, primarily composed of dolo-thrombolite and dolo-stromatolite reservoirs with partial bedding pore development, typically exhibit favorable physical properties. The average porosity can exceed 4%,with the average permeability of the former reaching 2.43×10^-3 μm²,while the average permeability of the latter is only 0.35×10^-3 μm². (3)A comprehensive analysis of diagenetic evolution reveals that the microbial carbonate reservoirs of the fourth member of the Dengying Formation have undergone a sequence of stages: sedimentary-quasi-symbiotic,supergene,shallow-to-medium burial,and deep-to-ultra-deep burial stages. (4)Analysis of reservoir distribution patterns in the study area indicates that the reservoir distribution weakens from the platform interior to the platform edge. Overall,the ultra-deep dolomite in the fourth member of the Dengying Formation in the Penglai area follows a ternary reservoir model characterized by “sedimentary facies-fault-dissolution.” This study provides key insights into the characteristics and controlling factors of the ultra-deep dolomite reservoirs in the Penglai area of the Sichuan Basin,offering significant guidance for future ultra-deep oil and gas exploration in the region.

Key words: ultra-deep carbonates, reservoir characteristics, main controlling factors, Dengying Formation, Penglai area, Sichuan Basin

中图分类号: 

• P588.24+5