Study On The Change Rule Of Development Index And Influence Factors In The East Of Xingshi District

The east part of Xingshi District was put into development in 1971 and entered ultra-high water cut period in 2005.After the fine tapping adjustment in 2010,the adjustment of water control and efficiency improvement,mainly focused on the development of precision controlled fracturing and extended reach wells,was implemented in 2016.After two development adjustments,the oil production did not decrease and water cut did not increase,and the change rule of development indicators changed a lot compared with that before the adjustment.Therefore,it is necessary to study the changing law of development indicators,analyze the main controlling factors of development indicators,and clarify the reasonable technical boundaries of water drive development.In this paper,numerical simulation and reservoir engineering theory are combined to study the law of production decline and water cut rise.Through single factor and grey correlation multifactor analysis,the influencing factors of decline rate and water cut rise rate are given.Based on the establishment of geological model and the history matching in the east part of Xingshi District,the distribution of remaining oil is studid.The results show that the utilization degree of different sands varies greatly.The recovery degree of channel sand is48.2%,that of interriver sand is 44.2%,and that of useless reservoirs is only 25.4%.The study on the decline of production of the research area and well pattern shows that the relationship between natural decline rate and comprehensive decline rate of different well pattern before fine tapping potential period is secondary&tertiary infill well pattern>first infill well pattern>basic well pattern.After fine tapping potential,the contribution of secondary&tertiary infill well pattern to decline rate is more than 50%.The whole area conforms to the law of exponential decline,and the decline rate of the whole area is reduced from 8.4%in fine tapping potential stage to the level of water control and efficiency improvement.The grey correlation analysis shows that the change of decline rate is mainly affected by measures,new wells and fluid production.The water-drive characteristic curve method is used to study the water-cut rising law in the study area.The results show that the water-cut rising rate decreases from 2.19%before the fine tapping potential to-0.04%during the water-control and efficiency-increasing stage.The water-cut rising rate is mainly affected by water storage rate,water injection rate and liquid production.Reservoir engineering method is used to study the reasonable injection-production pressure difference.The results show that the reasonable annual injection volume of basic well pattern,first infill well pattern and secondary&tertiary infill well pattern are39.7×10~4t,52.7×10~4t and 150.2×10~4t respectively,and the reasonable annual liquid production is 71.6×10~4t,32.8×10~4t and 93.6×10~4t.After optimization of injection and production parameters,the cumulative oil increment can be 12.1×10~4t and oil recovery can be increased by0.51 percentage points.