Study on water displacement and imbibition features of Chang6 & Chang8 tight oil reservoir in Ordos Basin
Tight oil is rich in Ordos Basin,mainly well-developed in Chang6 Chang8 reservoir groups of Yanchang Formation.Currently,it is an important goal to increase reserves and production.This study deepens the understanding of reservoir characteristics and flow laws to push forward the large-scale effective development of such reservoirs.Based on the previous research,this study introduced new techniques of nanometer-scale CT scanning,NMS,and high precision fluid metering to systematically study microcosmic pore-throat characteristics,occurrence phases of crude oil,water displacement and imbibition features in tight oil reservoirs.The research results show that multi-scale pores exist in tight oil reservoirs,dominated by the assembly of fine-pore and thin throats with good connectivity.Physical simulation studies show that the content of crude oil in large and medium pores is much greater than that in small pores,and the crude oil in a free state with good flowability is main object of oilfield development.The water displacement experiments indicate an effective displacement system can be established when displacement pressure is greater than the threshold pressure gradient in tight oil reservoirs.Water displacement efficiency could be improved with increasing displacement pressure.Laboratory results of NMS combined with water displacement and imbibition experiments show clearly that crude oil mainly contained in relatively large pores is produced previously,while that in small pores is hard to produce,no matter how it is developed by means of water displacement or imbibition.The research results can provide evidence for seeking more effective development technology.
万方数据
维普
