准噶尔盆地石北凹陷岛弧环境下火山—沉积建造特征及源储发育模式——以石炭系姜巴斯套组为例

Characteristics of volcanic-sedimentary formations and developmental patterns of source and reservoir rocks in an island arc environment of Shibei Sag, Junggar Basin: taking the Carboniferous Jiangbasitao Formation as an example

熊伟 王越 熊峥嵘 梅文科 白仲才 蔡倩茹 宋智华

XIONG Wei WANG Yue XIONG Zhengrong MEI Wenke BAI Zhongcai CAI Qianru SONG Zhihua

中国石化 胜利油田分公司 勘探开发研究院，山东 东营 257015

Exploration and Development Research Institute, Shengli Oilfield Company, SINOPEC, Dongying, Shandong 257015, China

准噶尔盆地石北凹陷位于盆地东部的陆梁隆起带北部，前期针对石北凹陷石炭系火山岩圈闭勘探一直未获突破。近期完钻的准北6井揭示了其石炭系姜巴斯套组自生自储型油气藏具有较大的勘探潜力，但以往针对这类储层的成因及分布研究较少。为了深入研究石北凹陷岛弧环境下火山—沉积建造特征及其源储发育模式，在前人研究的基础上，利用钻井岩心、地震及测试资料，结合烃源岩地球化学特征分析，对姜巴斯套组火山—沉积建造、烃源岩特征进行了系统研究，建立了岛弧控制下的火山岩—火山碎屑沉积岩—烃源岩发育模式，以期为具有相同沉积背景的地区油气勘探提供理论依据。研究表明，石北凹陷姜巴斯套组中基性火山岩形成于与俯冲相关的岛弧环境，火山建造主要为近火山口爆发相、近火山口溢流相、远火山口爆发相，沉积建造以岛弧侧翼的扇三角洲相凝灰质砂砾岩、砂岩与远岛弧低洼地带的滨浅海相凝灰质泥岩为主；姜巴斯套组凝灰质泥岩为一套处于成熟—高熟阶段的中等烃源岩，呈北西—南东向条带状分布，厚度分布在100~500 m之间；姜巴斯套组火山岛弧间歇喷发，远岛弧低洼地带凝灰岩与滨浅海凝灰质泥岩互层状分布，凝灰质泥岩与扇三角洲砂砾岩、岛弧火山岩具有良好的源储配置关系，两类储层为下一步重点勘探方向。

The Shibei Sag is located in the north of Luliang Uplift in the eastern Junggar Basin. There has been no breakthrough in the exploration of Carboniferous volcanic traps in the Shibei Sag in the past years. Recent drilling of well Zhunbei 6 reveals that the self-generating and self-preserving oil and gas reservoirs in the Carboniferous Jiangbasitao Formation have great exploration potential. However, there is scarce study on this type of reservoir. In order to study the characteristics of volcanic-sedimentary formations and developmental patterns of source and reservoir rocks in an island arc environment of Shibei Sag, the volcanic-sedimentary formations and source rock characteristics of the Jiangbasitao Formation were systematically studied based on previous study, drilling cores, seismic and test data, as well as the analysis of geochemical characteristics of source rocks, and the developmental pattern of volcanic, pyroclastic and source rocks under the control of island arc was established, with the aim of providing theory basis for oil and gas exploration in areas with the same sedimentary background. The results show that the basic volcanic rocks of the Jiangbasitao Formation in the Shibei Sag were formed in an island arc environment related to oceanic subduction. The volcanic formations are mainly composed of near-crater explosive facies, near-crater overflow facies and far-crater explosive facies. The sedimentary formations are dominated by fan delta facies tuffaceous glutenite and sandstone in the franking regions of the island arc and littoral neritic facies tuffaceous mudstone in the low-lying area of the far island arc. The tuffaceous mudstone of the Jiangbasitao Formation is a set of medium source rocks in the mature and high-maturity stages, which have a banding distribution along the northeast-southwest direction with a thickness of 100-500 m. During the sedimentary period of the Jiangbasitao Formation, the volcanic island arc erupted intermittently, and the tuff in the low-lying area of the far island arc and the littoral neritic facies tuffaceous mudstone were interbedded. The tuffaceous mudstones have a good source-reservoir configuration relationship with fan delta glutenite and island arc volcanic rocks. These two types of reservoirs are the key exploration directions in the next step.

中国石化科技部项目“准噶尔盆地石炭—二叠系潜力评价与目标优选” P21077-1

https://doi.org/10.11781/sysydz202304656