查干凹陷苏红图组火山岩储集特征及主控因素

利用岩芯、薄片、扫描电镜及压汞分析等测试手段，结合测井和地震资料，对查干凹陷苏红图组火山岩的储集特征进行了研究，明确了储集性能主控因素。研究表明，火山岩的主要储集空间为气孔、裂缝、溶蚀孔、溶蚀缝和微孔缝，玄武岩气孔、裂缝及溶蚀孔缝发育、分布广，为研究区主要的储集岩石类型，凝灰岩裂缝较发育，分布仅次于玄武岩，为研究区次要的储集岩石类型；火山岩期次越晚，原生孔、缝保存越好，爆发相-溢流相过渡相带和部分溢流相层段上部物性较好，气孔和裂缝的充填是火山岩物性变差的主要原因，构造缝及其伴生的风化淋滤、溶蚀作用极大地改善了火山岩的储集性能，火山岩矿物蚀变产生的黏土堵塞孔隙，使物性变差，同时使岩石的致密性变差，为后期的溶蚀改造创造了条件。

A Study on the Characteristics and Factors Affecting Volcanic Reservoirs in the Suhongtu Formation of the Chagan Depression

The reservoir characteristics of the Suhongtu Formation in the Chagan Depression were studied using rock cores, thin sections, scanning electron microscopy, and mercury intrusion porosimetry in combination with well logging and seismic data, to identify the main factors affecting reservoir performance. Results of this study indicated that the primary reservoir spaces in volcanic rocks are gas pores, fractures, dissolution pores, dissolution fractures, and microscopic pores and fractures. Basalt gas pores, fractures and dissolution pores were broadly developed and distributed, and basalt is the main type of reservoir rock in the research area. Tuff fractures were also relatively well developed and were second only to basalt in terms of distribution, thus making tuff the second most important type of reservoir rock in the research area. The later the volcanic rocks are formed, the better is the preservation of their primary porosity and fractures. The explosive-effusive facies transition zone and parts of the upper section of the effusive facies have good petrophysical properties, and the filling of gas pores and fractures were the main cause of petrophysical degradation in volcanic rocks. Tectonic fractures and their associated weathering-induced leaching and dissolution greatly improved the reservoir performance of volcanic rocks. The clays generated during the alteration of volcanic minerals not only clog pore openings and degrade petrophysical properties, but also reduce the density of the rocks. These actions thus created the conditions for dissolution and alteration in subsequent periods.