Evaluation And Research On The Effect Of Hydrocarbon Injection Gas Flooding In DH Oilfield

DH1C? reservoir in DH oilfield is a massive bottom water reservoir on the whole,which was formally injected with hydrocarbon gas in July 2014 and has achieved good gas injection effect.However,there is no corresponding standard to quantitatively evaluate the effect of hydrocarbon gas flooding in the industry at present.Therefore,this paper puts forward a quantitative evaluation method for the effect of hydrocarbon gas flooding.This study can improve the technical support for the evaluation of the effect of hydrocarbon gas flooding and the adjustment of gas injection in DH oilfield,and also provide a reference for the evaluation of the effect of hydrocarbon gas flooding in similar clastic reservoirs.In this paper,the dynamic parameters that need to be considered in effect evaluation are obtained by analyzing the production performance of DH oilfield;the gas drive chart is deduced and established,which can be used to calibrate the gas drive recovery of reservoirs;the evaluation criteria of water drive,profile control and displacement effect are analogized,the evaluation methods of carbon dioxide injection and the evaluation methods of oil field development effect at home and abroad are established,and the evaluation criteria of hydrocarbon injection gas drive effect are established by applying this standard.The effect of hydrocarbon gas injection in oil field has been evaluated and studied,and the following conclusions and understandings have been obtained:(1)The order of response of the effective production performance characteristics of single well in DH oilfield is as follows:the dynamic liquid level rises,the daily gas production at wellhead increases,the fluid/oil production increases,and the water cut decreases.(2)After gas injection in DH oilfield,production dynamic parameters such as pressure and daily oil production of single well and whole reservoir have been improved obviously,water cut of whole reservoir has decreased,daily oil production has remained stable,formation pressure has become stable,4 production wells have turned to self-blowout production,and the effect of gas injection is obvious.(3)Established a gas drive chart with the introduction of pseudo-water cut and comprehensive consideration of oil,gas and water phases,so as to make the recovery calibration more accurate.The applicable condition of this gas drive chart is that the gas drive of reservoir is in the middle-high or high gas production stage.The final recovery rate of gas drive in DH oilfield is 60%by using the established gas drive chart.(4)The established gas displacement chart is a composite chart which contains both water drive and gas drive,and can be degenerated into water drive Tong's chart.In practical application,two methods are used to obtain the formula of actual reservoir gas drive chart,which makes the calibrated recovery factor more meaningful.(5)The evaluation criteria of hydrocarbon gas flooding effect in clastic reservoirs with 16 indexes are established,which can provide reference for evaluation of hydrocarbon gas flooding effect in clastic reservoirs.The evaluation of gas injection effect in DH oilfield has been completed by using this standard.The evaluation result is excellent.It is suggested that the scale of gas injection should be further increased.