Single Well Nitrogen Injection Parameter Optimization Research In Seam Hole Type Carbonate Reservoir

TH oilfield ordovician reservoir is the carbonate karst cave reservoir.Reservoir is characterized by seam hole development and large cave is the main reservoir space.With the characteristics of strong randomicity fluid distribution and complicated oil-water relationship,TH oilfield development is difficult.TH oilfield is currently the natural energy as the main development mode,part of the implementation of the water injection development,but the overall development effect to be further improved.As enhanced recovery technology with nitrogen injection developed maturely,the TH oilfield has implemented the gas injection test for the water injection failure and the bottom water coning problem of the fractured carbonate reservoir.In this paper,the problems that the effect of gas injection in single well is different greatly,and the effect of gas injection in unit is general is to study.With comprehensive use of earthquakes,drilling and completion,water injection curve,well test data,the main work is as follows:(1)Analysis of factors affecting gas injection efficiency;(2)Study on Optimization of nitrogen injection parameters.A fine geological model of typical wells is established by using cavity and hole carving technology,and reservoir size is calculated by reservoir engineering method.The optimization of injection and production parameters is completed by historical simulation of numerical simulation model.The optimization of injection and production parameters mainly include:nitrogen injection rate,gas injection rate,shutoff replacement time,liquid production strength,etc.Through the research,this paper expounds on the two Wells of nitrogen injection development scheme of reasonable parameters.(1)The S80 well reasonable injection-production parameters as follows:cycle gas injection for 70?80×104m3,gas injection speed is 4?5×104m3/d,shut-in replacement time 10 to 12 days,maximum daily fluid withdrawal intensity should not more than 40m3/d,gas injection simulation shows 7 rounds round increased 85000 tons of oil,gas injection recovery degree is 22%;(2)The TK672 well reasonable injection-production parameters as follows:cycle gas injection for 60?70×104m3,gas injection speed is 10?15x104m3/d,shut-in replacement time for 15 days or so,maximum daily fluid withdrawal intensity suggest no more than 50m3/d.Finally,preliminary gas injector principle of selecting well are summarized,can provide certain reference for field implementation of nitrogen injection development.