黔北地区石牛栏组气藏特征分析与开发展望

Gas Reservoir Characteristics Analysis and Development Prospects of Shiniulan Formation in Northern Guizhou Area

摘要: 下志留统石牛栏组地层在川东南–黔北地区广泛发育，已在黔北地区多口井钻遇良好气显示。进一步分析石牛栏组气藏特征，可为区域石牛栏组天然气开发利用提供指导。通过对石牛栏组地层岩心观察、薄片分析鉴定结合黔北地区已钻井的钻井、测井、录井以及实验分析测试资料对石牛栏组岩性特征、地球化学特征、物性特征及含气性特征进行分析总结。结果表明：石牛栏组主要储层发育在其下段泥灰岩互层中；储层中泥页岩虽然具有一定的有机质，但含量低；储层孔隙度在1.2%~2.7%之间，平均2.1%，渗透率平均为0.002毫达西，属特低孔、特低渗储层，孔隙度与渗透率呈现弱正相关关系；石牛栏组气测显示活跃，但相对于新滩组和龙马溪组含气性地球物理响应无明显异常，或因含气地层纵向不稳定、厚度薄，平面连通性差所导致；综合分析认为研究区石牛栏组气藏与页岩气成藏特征有明显差别，含气性可能与裂缝的发育程度有关。建议在后期勘探开发中加强石牛栏气层成藏类型和主控因素研究，找到裂缝、孔洞发育区域并采取常规油气方式进行尝试开发，进一步评价石牛栏组气藏开发潜力。

Abstract: The Lower Silurian Shiniulan Formation is widely developed in the southeastern Sichuan-Northern Guizhou area, and good gas indication has been seen during the drilling of many wells in the northern Guizhou area. Further analysis of the gas reservoir characteristics of the Shiniulan Formation can provide guidance for the development and utilization of the natural gas of the Shiniulan Formation in the region. Based on core observation, thin section analysis and identification of Shiniulan Formation, combined with drilling, logging, logging and experimental data, the lithology, geochemistry, physical property and gas-bearing characteristics of Shiniulan Formation are analyzed and summarized. The results show that the main reservoirs of the Shiniulan Formation are developed in the marl interbeds in the lower section; the shale in the reservoirs has a certain amount of organic matter, but the content is low; the porosity of the reservoirs is between 1.2% and 2.7%, with an average 2.1%, with an average permeability of 0.002 millidarcy, belonging to ultra-low porosity and ultra-low permeability reservoirs. The porosity and permeability show a weak positive correlation; the gas survey of the Shiniulan Formation shows that it is active, but it is relatively active compared to the Xintan Formation and the Xintan Formation. There is no obvious abnormality in the gas-bearing geophysical response of the Longmaxi Formation, or the gas-bearing strata are longitudinally unstable, thin, and poor in plane connectivity; comprehensive analysis suggests that the gas reservoirs of the Shiniulan Formation in the study area have the characteristics of shale gas accumulation. The obvious difference is that the gas content may be related to the degree of fracture development. It is recommended to strengthen the study of the accumulation type and main controlling factors of the Shiniulan gas reservoir in the later exploration and development, find the cracks and cavities developed areas, and adopt conventional oil and gas methods for trial development, and further evaluate the development potential of the gas reservoir of the Shiniulan Formation.