玛南斜坡区上乌尔禾组弱胶结砂砾岩储层特征及控制因素

为明确准噶尔玛南斜坡区二叠系上乌尔禾组弱胶结砂砾岩储层对油气富集的影响,在岩心观察、薄片鉴定和分析化验等实验资料的基础上,对研究区储层特征和控制因素进行研究。研究结果表明:上乌尔禾组储层为泥质杂基充填弱胶结低孔低渗砂砾岩,结构成熟度和成分成熟度均较低,孔隙类型以剩余粒间孔为主,发育大—中孔中—细喉道型、小—微孔细喉道型和微孔—裂缝型3类储集空间;一类储层平均孔隙度大于9.0%,平均渗透率大于10.000 mD,具大—中孔中—细喉道的孔隙结构特征。储层的质量受沉积环境直接控制,三角洲扇前缘水下分流河道微相为优质储层沉积相。古地貌特征间接影响储层物性,古沟槽区水动力强,泥质含量低,物性好。研究区成岩作用以压实作用为主,对储集空间改造有限,砾石支撑抑制压实作用使原生粒间孔得以大量保存。研究结果丰富了玛南斜坡区二叠系上乌尔禾组砂砾岩储层特征,对后期砂砾岩储层的深入研究具有一定的指导意义。

Characteristics and Controlling Factors of Weakly Cemented Glutenite Reservoir in Permian Upper Urho Formation,South Slope of Mahu Sag

In order to identify the influence of weakly cemented glutenite reservoirs in the Permian Upper Urho Formation,south slope of Mahu Sag,Junggar Basin,the reservoirs in the study area were studied for reservoir characteristics and controlling factors on the basis of experimental data such as core observation,slice identification,and analysis of chemical examinations.The results of the study showed that the reservoir in the Upper Urho Formation was a weakly cemented glutenite reservoir with low porosity and permeability,mudstone filling at bottom,low structural maturity and composition maturity.The type of pores was dominated by residual inter-granular pores,and there are three types of storage spaces:1)macro-porous and meso-porous medium to thin throats,2)micro-porous thin throats,and 3)micropores and fractures;the average porosity of the first type of reservoir was greater than 9.0%and the average permeability was greater than 10.000 mD,showing the pore structure features of macro-porous and meso-porous medium to thin throats.The reservoir quality is directly controlled by the sedimentary environment,and the microfacies in subaqueous distributary channel at the front edge of the delta fan were high-quality reservoir sedimentary facies.The palaeogeomorphic characteristics indirectly affect the reservoir physical properties,with strong hydrodynamics,low shale content and good physical properties in the paleotrench area.The diagenesis in the study area was dominated by compaction,and the improvement of the reservoir space was limited.The gravel support inhibited the compaction,so that a large number of primary inter-granular pores could be preserved.The results enrich the glutenite reservoir characteristics of Permian Upper Urho Formation,south slope of Mahu Sag,and have a certain guiding significance for the further study of glutenite reservoir.