琼东南盆地崖城13-1气田渐新统陵三段沉积物源综合分析

Provenance Analysis of 3rd Member of Oligocene Lingshui Formation in the Yacheng 13-1 Gasfield,Qiongdongnan Basin

物源体系分析是确定储层沉积的成因类型、空间展布与演化规律的关键问题之一,本文通过古地貌、重矿物、岩屑成分和结构与地层倾角测井等多种方法的综合分析,对琼东南盆地崖城13-1气田渐新统陵三段物源进行系统研究,确定了研究区陵三段沉积时期的物源体系主要来自北西方,碎屑沉积物以石英含量高的岩屑长石质石英砂岩与长石质石英砂岩为主,并根据重矿物组合特征分析,认为物源区母岩类型主要有酸性岩浆岩、变质岩以及再改造的沉积岩等。由于物源区距研究区距离适中,地形有一定的坡度,容易产生机械破碎的大块碎屑,故此种母岩特征是研究区陵三段辫状河三角洲砂体成因及沉积特征的内在因素。

Provenance system analysis is one of the key means for determining the genetic type,spatial distribution and evolution of the reservoir.In this paper,Based on an integrated analysis of palaeogeomorphology,heavy minerals,composition and structure of debris and dip log data,the authors systematically studied the provenance of 3rd Member of Oligocene Lingshui Formation in Yacheng 13-1 Gasfield within Qiongdongnan Basin and revealed that the provenance system of the study area was derived from the northwest during the deposition of 3rd Member of Lingshui Formation.The clastic sediments are mainly lithic feldspathic quartzite and feldspathic quartzite with high content of quartz.An analysis of heavy mineral assemblages shows that the rock types of the source area were mainly acidic magmatic rocks,metamorphic rocks and reworked sedimentary rocks.Because of the moderate distance from the source area to the study area and the existence of some slopes between them,the source area was likely to produce large debris by mechanical crushing and this type of mother rock might have been the inherent factor responsible for the formation of braided channel delta sandstone and sedimentary characteristics in 3rd Member of Lingshui Formation in the study area.