箕状断陷盆地坡折带与隐蔽油气藏勘探: 以二连盆地乌里雅斯太断陷南洼为例

Slope-Break Zones in Half-Graben Fault Basin and Exploration of Subtle Pools: A Case Study of the Southern Sag ofW uliyastai D epression in Erlian Basin

( 1 中国石油勘探开发研究院西北分院 2 华北油田分公司勘探部)

Northw est Branch of Research Institute
of Exploration and Deve lopment, CNPC, Lanzhou
730020, China

Genera lly, there a re mo re than one gentle-slope zone and
a steep- slope break zone in the ha l-f g raben fault basin. These
slope-break zones not on ly contro lled the distr ibution o f the
depositiona l system traces and the sand bodies, but also
contro lled the forma tion o f the subtle poo ls. Based on the
classical sequence stratig raphy princ iples and the concept of
the slope-break zone, three slope-break zones are identified in
the gentle slope-break zone of the Southern Sag ofW uliyasta i
Depression in Er lian basin. The first one is a structural o r
erosiona l slope-break zone, the second one is a structura l o r
sedim en tary slope-break zone and the th ird one is a structura l
slope-break zone. A fter ana lyz ing the fo rm ation characters of
subtle poo ls in these slope-break zones, it considered that the
second slope-break zone is the most important belt fo r
explorating sub tle poo ls.