Study On Development Effect Evaluation And Well Patternthickening In South Songfangtun Oilfield

South Songfangtun Oilfield is put into production with300×300m inverted nine-spotwaterflood development pattern in1993. The target zone is Putaohua oil layer, which has lowpermeability and extremely low abundance. At present, the oilfield has entered medium-highwater cut development stage. The existing well pattern faces the problems of seriouswater-out in main block, poor injection-production relationship and high producing statusvariation, etc. So, evaluating the waterflooding development effect, deepening the research ofremaining oil distribution characteristics and exploring the injection-production systemadjustment mode which is suitable for this block are the key to water control, potentialtapping and efficient development.Based on the actual dynamic and static data of South Songfangtun Oilfield, usingreservoir engineering methods such as empirical formula, water flooding curves and Tong’schart, the work of waterflooding development effect evaluation is carried out in this thesis,including waterflooding recovery, water cut escalating rate, utilization factor of waterinjection, producing degree of waterflooding reserves, oil producing capability and wellpattern adaptability. Then a comprehensive evaluation system of waterflooding developmenteffect in South Songfangtun Oilfield is established by analytic hierarchy process (AHP) andfuzzy comprehensive evaluation method. Evaluation results show that the ultimate recoveryunder present well pattern is21.3%. Water cut goes up too fast, utilization factor of waterinjection is low, oil producing capability is poor, the existing well pattern density is low anddoesn’t meet the requirement of exploitation. The waterflooding development level is low.Typical block in South Songfangtun Oilfield is selected and3D facies-controlledgeological model is constructed using Petrel modeling software. The law of remaining oildistribution is studied by Eclipse numerical simulation software and4remaining oil types aredetermined by sedimentary microfacies method, which are production without injection,one-way water injection response, poor water intake in injection well and fault-screened type.Finally the proportion of different remaining oil types are quantified.On the basis of above research,3well pattern thickening adjustment schemes aredesigned and the optimal one is determined by comparing the development effect. Theoptimal well pattern thickening scheme is inverted nine-spot encryption with flexible infillnear fault and in remaining oil enrichment areas, coupled with converting oil well intoinjection well and restoring the closed oil and water wells. It forecasts that ultimate recovery of the optimal scheme is26.31%, which is5.4%higher than the one of present well pattern.The infill adjustment is economic and effective.In this thesis, the underground oil and water distribution laws of South SongfangtunOilfield are clarified. The optimized scheme has an important guiding significance for thenext injection-production system adjustment.