鄂尔多斯盆地西峰油田主要储层砂体的成因与演化

Genetic and Evolution of Main Reservoir Sand Bodies in Xifeng Oilfield,Ordos Basin

以鄂尔多斯盆地西峰油田上三叠统延长组为例,利用层序地层学理论对辫状河三角洲前缘沉积体系中以水下分流河道和河口坝两种储油砂体为主的多种成因组合进行了研究,将其划分为水下分流河道组合区、水下分流河道与河口坝混合区和河口坝组合区。详细刻画了辫状河三角洲前缘中主要储油砂体的成因类型,将水下分流河道成因砂体划分为叠加式水下分流河道砂体和完整式水下分流河道砂体两类;将水下分流河道与河口坝复合成因砂体划分为坝上河和河上坝砂体两类;将河口坝成因砂体划分为叠加式河口坝和孤立式河口坝砂体。讨论了各类成因砂体的形成机制。

Taking Late Triassic Yanchang Group in Xifeng Oilfield, Ordos Basin as an example, this paper studies the various causes for the submarine distributary channel and the river mouth dam reservoir sand bodies in the braided river delta front depositional system in the light of sequence stratigraphy theory. It suggests that the system shoud be classified into three genetic portfolio areas：＂submarine distributary channel area＂,＂submarine distributary channel and river mouth dam mixing zone＂ and ＂river mouth dam area＂. With detailed description of the genetic types of the main reservoir sand bodies in braided river delta front, it divides submarine distributary channel genetic sand bodies into superposition type submarine distributary channel sand bodies and integrity type of submarine distributary channel sand bodies; the submarine distributary channel and the river mouth dam compound genetic sand bodies into the dam on the river and the river on the dam; and the river mouth dam genetic sand bodies into the superimposition type river mouth dam and the orphaned vertical river mouth dam. What＇s more, it discusses the formation mechanisms of various genetic sand bodies.