准噶尔盆地北三台凸起断裂结构特征及成岩封闭作用

断层具有复杂的内部结构,可划分为滑动破碎带和诱导裂缝带两个结构单元。断裂带内部成岩作用普遍发育,其中,胶结作用是断裂两侧诱导裂缝带中较常见的成岩作用,影响着断裂的垂向封闭性。利用地震、测井、岩心等资料定量化的对准噶尔盆地北三台凸起主要断裂进行结构划分,利用岩心、镜下薄片观察的方法研究断裂带成岩胶结作用。研究发现:断裂带成岩胶结作用显著,胶结物以方解石为主,还发现有粘土矿物、沸石、石英等胶结裂缝。大型主控断裂裂缝充填程度相比派生断裂高,胶结程度致密,对油气的封堵性能更强。通过镜下鉴定及流体包裹体均一温度测定发现:北三台凸起断裂带至少经历了3期大规模流体活动,多期的流体作用导致该区断裂的成岩封闭。

STRUCTURAL CHARACTERISTICS AND DIAGENETIC SEALING OF FAULTS IN THE BEISANTAI SWELL, JUNGGAR BASIN

A fault has a complex internal structure, which can be divided into slip damage zone and induced fracture zone. The internal diagenesis of the fault zone is widely developed, and the cementation is the most important diagenesis in the induced fracture zone on both sides of the fault, which plays an important role in the vertical sealing of the fault. The structure of the main faults in the Beisantai swell is divided quantitatively by using seismic, logging and core information, and diagenetic cementation of fault zone is studied through core observation and microscope observation of thin section. The results show that the cementation of fault zone is obvious and there are various types of cement, mainly calcite; clay minerals, zeolite, quartz and other cement are also found in fractures. Compared with the derived faults, the fracture filling and cementation of large main faults are more intense, and the sealing performance of the oil and gas is stronger. The identification under microscope and the uniform temperature test of fluid inclusion suggest that there were at least three periods of great fluid activities in the Beisantai swell, and the multiple fluid activities lead to the diagenetic sealing of the faults in this area.