塔北地区地震波衰减检测含气的多解性成因与排除方法  

Multi solution causes and elimination methods of seismic wave attenuation gas detection in Tarim Basin

作　　者：蒲仁海[1] PU Renhai(Department of Geology, Northwest University, Xi′an 710069, China)

机构地区：[1]西北大学地质学系,陕西西安710069

出　　处：《西北大学学报（自然科学版）》2021年第5期864-876,共13页Journal of Northwest University（Natural Science Edition）

基　　金：西北大学横向课题基金资助项目(34000000-19-ZC0613-0011)。

摘　　要：查明地震波衰减含气检测法多解性的地质成因、类型,并找到多解性的排除方法,对隐蔽油气藏的勘探和非常规气甜点的识别具有重要意义。研究表明,非含气衰减异常多由某种异常低速的岩性如煤层、钙质含量变低的砂岩、混积岩中的砂泥岩等引起。衰减地层的时代可以是较浅的古近系,也可以是埋深较大的古生界。具衰减异常的非含气地层衰减时的调谐厚度一般为20~100 m,衰减后的主频降低5~10 Hz或更多,衰减异常的平面形态和面积受控于低速体的类型和成因,有的为蛇曲状、带状或朵状,有的为微含气的圈闭形态,有的为面积可达数百平方公里的不规则形态。研究后认为,根据岩性法、圈闭成藏要素法和规模法等方法可以排除某些非含气地层引起的地震烃类检测异常,从而提高油气检测的成功率。Finding out the geological genesis and types of multi-solutions of seismic wave attenuation gas detection method,and finding the elimination method are of great significance for subtle reservoir exploration and unconventional gas dessert identification.In the process of looking for subtle gas reservoirs by seismic attenuation method through Fourier transformation in the northern part of Tarim Basin,several examples of attenuation caused by non gas reservoirs are encountered.Research results show that these non gas attenuation anomalies are usually caused by decrease of the compression wave velocity of strata,whose lithology mainly consists of coallow-velocity sandstone,and classic rocks in mixed rocks of terrigenous clastics and carbonates.The age of attenuation formation can be a shallow Paleogene or a deep buried Paleozoic.The tuning thickness of the low velocity attenuation interval is generally in 20~100 m,and the dominant frequency after attenuation is reduced by 5~10 Hz or more.The plane morphology and area of the attenuation anomaly are controlled by the type and origin of the low velocity rocks.Some of them look like meandering,banded or lobed sandbodies;some of them belong to hydrocarbon trap only containing noncommercial gas;some of them have a big irregular area of hundreds of square kilometers.After the study,it is considered that the seismic hydrocarbon detection anomalies caused by some non-gas-bearing strata can be eliminated according to lithology method,trap reservoir forming element method and scale method,so as to improve the success rate of hydrocarbon detection.

关 键 词：地震衰减 含气检测 地质成因 多解性 塔北 

分 类 号：P618.13[天文地球—矿床学]