神木气田S井区盒8段单砂体叠置模式及其对天然气分布的影响OA

The Shenmu gas field has entered a large-scale rapid production development phase.However,in the S well area,gas well production declines rapidly after commissioning,with low recovery rates and significant challenges in predicting remaining gas distribution.As the main producing layer in this area,the internal stacking patterns of single sand bodies in the He 8 member and their controlling mechanisms on natural gas distribution remain unclear,which restricts efficient field development.Therefore,this study fully utilizes core,logging,and production dynamic data to conduct microfacies analysis,single sand body identification,and stacking pattern classification for the He 8 member in the study area.It reveals the controlling mechanisms of stacking patterns on natural gas distribution from both qualitative and quantitative perspectives,with validation provided by production dynamic data.Research indicates that the He 8 member in the study area was deposited in a braided river delta front environment,developing three sedimentary microfacies:underwater braided channel,underwater braided inter-channel,and mouth bar.Based on vertical and lateral boundary identification markers for single sand bodies,the stacking patterns are classified into two major categories comprising six types:vertical stacking relationships(independent,superimposed,and cut-stacked)and lateral contact relationships(isolated,lateral-connected,and lateral-cut).Analysis of production dynamics and gas reservoir characteristics shows that the stacking patterns of single sand bodies collectively control the enrichment patterns of natural gas in the study area.Among them,sand bodies with vertical cut-stacked patterns and lateral-cut contacts exhibit the best connectivity,with physical properties and gas-bearing capacity significantly superior to other types,making them high-quality reservoirs for natural gas enrichment.The results of this study provide a theoretical basis for predicting remaining gas distribution and guiding efficient development in the Shenmu gas field.