摘要
乌南油田N21地层为一套砂泥岩薄互层的沉积组合,形成一些席状砂和透镜砂体,这些砂体是乌南油田的主要目的层段。储层岩石粒度偏细,以细砂、极细砂为主,岩石方解石胶结普遍,且含量好。研究区储层成岩阶段处于早成岩A末期到早成岩B早期,在早成岩A末期烃源岩释放大量有机酸,在砂岩中形成次生孔发育带,储层孔隙以残余粒间孔、粒间溶孔为主。储层物性差,属低孔—特低孔、特低渗—超低渗储层,属致密砂岩范畴。咸化湖盆沉积背景下的泥砂互层组合在压实作用下,泥岩中流体排向砂岩,导致砂岩方解石胶结是研究区岩石致密化的主要因素。
N2^1 formation of Wunan Oil Field is a set of sand-shale thin interbedding deposit, forming some sand sheets and lenticular bodies. Those sand bodies are the main target horizons of Wunan Oil Field. The grain size of reservoir rock is relatively fine, mainly fine sand and fine sandstone. Calcite of rock is well cemented and high in content. The diagenetic stage of the studied reservoir is from the late A period of early diagenesis to the early B period of early diagenesis. Hydrocarbon source rock released a large amount of organic acid in the late A period of early diagenesis, forming the secondary porous development zone in the sandstone. The reservoirs pores are mainly residual intergranular pores and intergranular dissolved pores. The physical properties of reservoir are poor. The porosity of the reservoir is low to super-low while the permeability is super-low to ultra-low, belonging to the scope of compact sandstone. Thanks to the effect of compactness on the mudstone and sandstone interbedding under the background of saline lake basin sedimentation, the fluids were drained into sandstone from mudstone, leading to cementation of calcite in the rock. This is the main factor for rock compactness in the research zone.
出处
《中国石油勘探》
CAS
2013年第1期22-28,共7页
China Petroleum Exploration
关键词
柴达木盆地
乌南油田
致密砂岩
储层特征
成因机制
Qaidamu Basin, Wunan oil field, compact sandstone, characteristics of reservoir, origin mechanism
