The Injection-production Policy Of Well Pattern Secondary Infilling In The Second District Of Dalugou Reservoir

Based on the geological characteristics and development characteristics of the reservoir in the Dalugou district,this paper carries out the dynamic analysis of the research area,summarizes the effective types of the oil well,and analyzes the main control factors.The results showed that the oil Wells in the study area can be divided into four categories according to the production status,which are the obviously effective Wells,the general effective Wells,the water flooded Wells,no effective Wells.According to the distribution of the production status of oil Wells,the research area is divided into the western effictive area,eastern effective area and not effective in central area,which is mainly caused by the distribution characteristics of sedimentary microfacies,the continuous condition of sand bodies,the corresponding degree of perforation of injection Wells and oil Wells,and the injection-production policies of Wells.At the same time,a new method to determine reasonable row spacing of the diamond inverted nine-spot well pattern in the ultra-low permeability reservoir is proposed.This new method takes threshold pressure gradient and the strong anisotropy in ultra-low permeability reservoir into consideration.In addition,one of the reservoirs of Chang 6 oil field in Ordos Basin is Chosen as the pilot area.The reasonable row spacing of the diamond inverted nine-spot well pattern should be 75m~100m in the central not effective area,but the actual row spacing is 140m,which leads to bad development efficiency of oil wells.While the row spacing of 140m in the western and eastern region is reasonable so that the well pattern does not need to be adjusted.This paper determines the reasonable technology policy by using reservoir engineering method and combining with actual production data.After considering the invalid water injection rate of injection Wells,the rational injection-production ratio in the whole area is 2.52,the western effective area is 2.0~2.2,and the eastern effective area is 1.5~1.6,and the not effective area in the center is 3.5~3.7;the reasonable level of formation pressure is 114%~118%;injection rate of western effective area should be maintained in18~19 m~3/d and the daily liquid production rate should be 2.8~2.9m~3/d,the eastern effective area should be maintained in 17~18m~3/d and 2.6~2.8m~3/d,and the centeral not effective area should be maintained in 16.5~17.5m~3/d and 1.8~2.0m~3/d.The bottom hole flowing pressure of old oil Wells should be 3.0~3.5MPa and the infilling Wells should be 4.0~4.5MPa.Reasonable oil recovery rate is 0.8%~1.0%.Five new ways of secondary infilling adjustment are proposed in this paper,and then the development efficiency of each program of such secondary infilling adjustment is predicted and compared by numerical simulation.The result shows that the plan F5 is the most optimal for enhancing the oil recovery about 4%.In addition,this paper determines that there are 24 old oil Wells and 51 infilling oil Wells need perforation,and 8 Wells need acidizing technology and 9 water injection Wells need profile control.