The Study On Shan₁ Reservoir Evaluation Of Q1 Wellblock In Ordos Basin

The Shan₁ reservoir of Q1 wellblock in Ordos Basin is a typical low porosity low permeability gas reservoir.At present,most of the gas have been discovered in Ordos basin is located in the northern basin.The gas resources of upper Paleozoic in southern basin still have development potential,How to find a new gas exploration blocks in the vast south basin is the key to sustainable development of oilfield.The research object of this paper is Shan₁ reservoir of Q1 wellblock.Based on the core data,logging data and the production dynamic data of 25 well in study area,the research of stratigraphic fine classification and correlation,sand thickness distribution regulation and sand top micro-structural features,sedimentary characteristics analysis,four characters relationship and reservoir parameters distribution characteristics,reservoir heterogeneity,reservoir classification evaluation is carried out.The research shows that Shan 1 reservoir of the study area can be divided into 3 small layers,Shan₁¹,Shan₁² and Shan₁³.Among them,thickness of Shan₁³ is about 17 m,thickness of Shan₁² is about 16 m,and thickness of Shan₁¹ is about 15.6m.Through stratigraphic fine classification and correlation,stratigraphic correlation is well and variation of stratigraphic thickness has little change.The distribution mode in each small layers of Shan₁ is from southwest to northeast.The development of sand body in Shan₁³ is better among 3 small layers.Average thickness of sand body in Shan₁³ is about 8.6m and Shan₁³ is main gas layer.Average thickness of sand body in Shan₁² is about 5.1m.The development of sand body in Shan₁¹ is worst,which is about 2.5m.Overall sand top micro-structural features in researched area present monocline which tilts to the west.The structural isolines present a series of low-amplitude nose-shaped which is from northeast to southwest.The study area develops mainly deposits procreation fan delta frontal surfacies which can be divided 3 sedimentary microfacies,underwater distributary channel,natural levee and subsea distributary bay.In vertical direction of source,malleability of underwater distributary channel in Shan₁³ is best.Shan₁² takes second place and Shan₁¹ is worst.Along direction of source,malleability of underwater distributary channel in Shan₁³ is best.Shan₁² takes second place and Shan₁1 is worst.Base on research of reservoir four characters relationship,the interpretation model of porosity,permeability and gas saturation are founded.The 3 small layers plane distribution of porosity,permeability and gassaturation are drawn.These maps of reservoir parameters distribution are appropriate for thickness of sand body and sedimentary micro-facies plane distribution characteristic.According to the research of reservoir heterogeneity,among 3 small layers,the heterogeneity of Shan₁¹ is strongest which present strong heterogeneity.The heterogeneity of Shan₁³ is weakest,but it also presents less strong heterogeneity.According to the standard of reservoir classification in study area,Shan₁¹,Shan₁² and Shan₁³ can be classified to different reservoir types.Shan₁³ belong to the ??1?reservoir and it is the main reservoir.Shan₁² belong to the??2?reservoir and it is the potential reservoir.Almost of reservoir in Shan₁1 develops ? and? reservoir,which is poor reservoir.The conduction of this study has a certain reference function to follow-up developmental technological judgment in researched area.