火成岩储集层裂缝特征及成缝控制因素

基于新疆北部石炭系火成岩的最新勘探和研究成果，研究火成岩中发育的裂缝类型、控制因素，及裂缝对优质储集层发育和油气高产的控制作用。火成岩中发育不同产状（斜交缝、网状缝、水平缝、直劈缝）和成因裂缝（自碎缝、收缩缝、溶蚀缝、节理缝、构造缝），不同类型裂缝的流体渗流能力和渗流半径存在差异。裂缝发育程度受岩性、构造、早期成岩和后期成岩作用控制，在构造作用较弱地区，火成岩裂缝发育程度受岩性控制，在相同构造背景下不同岩性火成岩中裂缝发育程度不同；构造、早期成岩和后期成岩作用是火成岩成缝的主要控制因素，构造作用和后期成岩中的表生作用对火成岩成缝的贡献最大，构造作用强、风化淋滤时间长的区域，不同岩性火成岩中均发育裂缝，并能形成有利储集层，距主断裂带3 km范围是裂缝和有利储集层的集中发育区，油井离断裂越近越易高产、稳产。图10参21

Characteristics and controlling factors of fractures in igneous rock reservoirs

Based on the newest exploration and research achievements, the paper studies the types and controlling factors of the fractures in Carboniferous igneous rocks of Northern Xinjiang, and their influences on the high-quality reservoir and high production of oil and gas. Fractures with different occurrences (oblique fracture, net fracture, horizontal fracture and vertical fracture) and geneses (autoclasic fractures, contraction fractures, dissolved fracture, joint fracture and structural fractures) were developed in igneous rocks. The ability of fluid flow and seepage radius were different in various fractures. The development degree of fractures was controlled by lithology, tectonic movement, early and late diagenesis. It was controlled mainly by lithology in the areas of weak tectonic movement; it varied in different lithologic igneous rocks with the same tectonic background. The main controlling factors of forming fractures in igneous rocks were tectonic movement, late and early diagenesis, especially hypergenesis during the stage of late diagenesis. Various lithologic igneous rocks undergoing intense tectonic movement and long-time weathering developed fractures and favorable volcanic reservoirs that were concentrated in the area no more than 3 km away from main fault zone. The closer to the fault the well is located, the easier it gains high and stable production of oil and gas.