Provenance Analysis for Liushagang Formation of Wushi Depression,Beibuwan Basin, the South China Sea
Yuan Xiaoqiang
Yao Guangqing
Jiang Ping
Lu Jiang
Abstract：The Eocene Liushagang Formation,the main hydrocarbon-bearing stratum in Wushi depression,is a promising replacement area in Beibuwan basin.Provenance analysis of the sandbody is significant for better understanding of its distribution and "Source-to-Sink system",which facilitates in turn the oil-gas exploration and development in this area.However,the study in this area,especially on the provenance is very limited.In this study,the provenance of sediments in Eocene Liushagang Formation is analyzed by integrating with the seismic,lithological and electric properties,core,components of the sandstones,assemblage styles of the heavy mineral,and probability cumulative grain size curves.Results show as follows:(1)There are two provenances,one from north and the other from south,in the study area.Northern sourced well WS17-2 and WS16-1 area is mainly feldspathic litharenite with high feldspar contents.However southern sourced well WS22-7-2 and WS22-9 area is mainly litharenite with high lithic contents.(2) The well WS17-2 and WS16-1 area exhibits high tourmaline,hematite contents and low garnet contents,while the well WS22-7-2 and WS22-9 area exhibits high hematite,garnet,zircon contents and low tourmaline contents.(3) A large number of probability cumulative grain size curves indicate that northern sourced well WS17-2 area and southern sourced well WS22-7-2 and WS22-9 area share equivalent largest particle diameter (-2 to-lΦ) as well as suspended particulate diameter (2-3Φ).However both measures in well WS16-1 area are 0-1Φ and 3.6-4.0Φ,with:smaller scales implying characteristics of long distance transport.(4) The debris in study area shows poor sort and round,rich plastic debris and matrix,implying typical characteristics of sedimentary filling in small sag.It is concluded that the provenance of Liushagang Formation in Wushi depression is a typical example of small rift basin,with reservoir parameters mainly involved with compaction and matrix contents.
Keywords：provenanceSource-to-Sink systembeibuwan basinLiushagang Formationsedimentarypetroleum geology
Publication Date：2017-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：15( 2040-2054 )