琼东南盆地花岗岩潜山发育演化及控藏作用

Tectonic evolution of granite buried hill and its control on reservoir accumulation in Qiongdongnan Basin

以琼东南盆地地震、钻井及测年资料为基础,结合南海北部陆缘构造演化特征,分析了琼东南盆地花岗岩侵入期次和分布规律,论述了花岗岩潜山发育演化及控藏作用。研究表明,琼东南盆地发育印支期和燕山期两期花岗岩侵入,印支期花岗岩主要分布于NW向(低)凸起带,燕山期花岗岩分布于NE向(低)凸起带,琼东南盆地花岗岩潜山构造类型为残丘山,印支期花岗岩和燕山期花岗岩潜山演化都可划分为岩浆侵入期、暴露剥蚀期和定型埋藏期等阶段。盆地花岗岩潜山暴露剥蚀时间长,经历了多期次构造运动,发育网格状断裂,可形成风化壳型和断裂-裂缝型储层,松南低凸起花岗岩潜山被多凹环绕,发育断裂+砂体复合输导体系,是油气有利汇聚区。

Based on the gravity and magnetic,seismic,drilling,and age dating data of the Qiongdongnan Basin,combined with the tectonic evolution characteristics of the northern continental margin of the South China Sea,we analyzed the intrusion period and distribution law of granite in the basin,and discussed the development and evol-ution of granite buried hill and its reservoir control.Results show that the Indosinian and Yanshanian granite intru-sions developed in the basin.The Indosinian granites were mainly distributed in NW(low)uplift zone,and the Yanshanian granites were distributed in NE(low)uplift zone.The tectonic type of granite buried hill in the basin is residual hill.The evolution of granite buried hill in the Indosinian and Yanshanian periods can be divided into magmatic intrusion period,exposure and denudation period,and final burial period.The evolution difference between them is mainly reflected in the intrusion time of magma.The granite buried hill in the basin has been ex-posed and eroded for a long time,and has experienced multi-stage tectonic movements.The grid-like faults were developed,which formed weathering crust reservoirs and fault-fracture reservoirs.The Songnan Low Uplift is sur-rounded by multiple concaves,in which fault+sand body composite transportation system is developed,forming a favorable oil and gas accumulation area.