Causes And Countermeasures Of Low Production And Low Efficiency Of Chang 6 Reservoir In A Oil Area

Oil area A of Changqing Oilfield is located in the east side of Tianhuan Depression,Ordos Basin,and the main producing layer is Chang 6 oil formation.At present,the research area is in the middle and late stage of oilfield development.The number of low and inefficient Wells with daily production less than 1.0t is increasing,oil well production continues to decrease,and the oilfield development effect becomes worse.Guided by reservoir geology,sedimentology and reservoir engineering theory,based on field outcrop,drilling coring and logging data,and based on reservoir description,this paper carries out production performance analysis with well group as unit,combed out the causes of low yield and low efficiency,and formulated corresponding treatment countermeasures.On the basis of stratigraphic division and correlation,the structural characteristics,sedimentary facies characteristics and reservoir characteristics of Chang 6 reservoir group are studied.The results show that the thickness of Chang 6 reservoir varies greatly,and the developed nose-shaped uplift controls the distribution and flow of oil and water to a certain extent.Wells in different microfacies have different productivity and development effects,and the connectivity of sand bodies plays an important role in controlling low productivity and inefficiency.The existence of high permeability bands and fractures makes water channeling easily during oil-water two-phase flow,which leads to high water cut in oil Wells.The physical property of Chang 6 reservoir is poor,which reduces the injection-production capacity.The Wells with low pore and permeability values and oil saturation values are located in the edge of the study area with poor sand body development,which is easy to form low productivity and low efficiency Wells.Based on the further understanding of the geological characteristics of the reservoir in the study area,this paper studies and analyzes the connectivity between oil and water Wells,the direction of water flooding and the direction of water inflow by using the method of reservoir production performance analysis,and makes clear the development factors of the poor development effect in the study area are energy shortage and formation clogging.On the basis of exploring the mechanism of low yield and low efficiency caused by different geological and development factors,some treatment measures,such as water plugging of oil well,profile control of water well,acidification and injection increase,injection transfer and refracturing,are put forward.