重磁勘探在中牟凹陷油气勘查中的应用

Gravity and Magnetic Survey Application on Oil and Gas Exploration in Zhongmu Depression

摘要: 在油气勘查中，重磁勘探对划分断裂构造及构造单元、查明目标区的地层结构、含磁性火山岩的分布、了解勘探区及油气的生、储、运、保条件、圈定目标靶区是较为行之有效的勘探方法，笔者对中牟凹陷重磁勘探工作取得的勘探成果进行了充分的分析和研究，希望能为油气勘查工作部署提供借鉴。通过重磁勘探在中牟凹陷油气勘查中的应用，在研究区划分出4个一级构造单元，及8个二级构造单元。认为中牟凹陷边界断裂“左行走滑拉分”是中牟凹陷形成的主导因素，其从中生代(侏罗纪)到早古近纪，沉积中心由北向南迁移，凹陷内的南部凹陷为南断北超的“箕”形凹陷，具有西深、东浅的特征；中牟凹陷的构造演化主要分为三期：侏罗纪左行走滑拉分盆地发育期，早古近纪为断陷期，晚古近纪、第四纪为坳陷期；认为油气勘探的有利区段为白沙断阶，列为第一勘探对象，如果有所突破，第二步对官厂构造带的南部构造高点实施钻探，在取得成效之后，勘探可在官厂一带进行。

Abstract: During the whole process of oil and gas exploration, gravity and magnetic survey is an effective exploration method in dividing faults and tectonic units, finding out stratum structure, the distribution of volcanic rocks with magnetic property, realizing the condition of oil and gas resources producing, storage, migration and preservation and delineation for target areas. The author hackles the exploration achievements by gravity and magnetic survey in Zhongmu depression and hopes to provide reference for next exploration arrangement. Based on the application for gravity and magnetic survey in the Zhongmu depression, four first-order tectonic units and eight second- order tectonic units are divided in this area. And the conclusions are drawn as follows: boundary faults of Zhoumu depression with strike-slip and pull apart play an important role in Zhongmu depression formation. The depocenter of Zhongmu depression migrated southwards from Mesozoic to early Paleogene. There are faults in the south overlap in the north in the southern sag. And it is deeper in the west and shallower in the east. The tectonic evolution can be divided into three stages: developing stage in Jurassic, faulted period in early Paleogene, depression period in late Paleogene and Quaternary. Favorable section of oil and gas exploration is Baishafault terrace which can be ranked as the priority target. After a breakthrough drilling exploration can be put into effect in the south high spot of Guanchang tectonic belt.