Study On Spontaneous Imbibition Characteristics And Water Huff-Puff Parameters Of "Three Low" Sandstone Reservoirs

The"three low"sandstone reservoirs are mainly characterized by low permeability,low pressure,and low fluidity.Due to poor reservoir properties,low reservoir pressure,weak flow capacity,the water recovery efficiency is low.And after the reservoir fracturing,water channeling is prone to occur and development is very difficult.Accordingly,the water huff-puff of horizontal well,which uses imbibition power,has become a potential technology for the development of"three low"sandstone reservoirs.In this paper,through the imbibition experiment at normal temperature and pressure,the imbibition experiment under actual temperature and pressure conditions,NMR experiment,the experiment of screening surfactant,the imbibition experiment of adding surfactant and the optimization of water huff-puff parameters,it has deepened the understanding of its’imbibition mechanism,has screened out highly effective surfactant and has developed a plan for the best combination of different oil production parameters for water huff-puff.By comparing and analyzing the imbibition efficiency and imbibition rate under the actual pressure and temperature co nditions and normal temperature and pressure conditions,it is believed that the imbibition power and the imbibition resistance can be increased under the actual pressure and temperature conditions.A ideal calculation model of imbibition depth is established,and the core imbibition depth is calculated.It is considered that the depth entered in the early rapid imbibition stage belongs to the range of centimeter.Based on NMR experiments to study the feature of imbibition,the fluid flow law during spontaneous imbibition of the core is obtained.The pore types in the study area are mainly medium and large pores.The smaller the pore throat,the greater the rate of imbibition.The capillary force plays a leading role in the imbibition process.The rapid phase of spontaneous imbibition occurs mainly at the core surface,and the middle and deep layers have relatively small contributions to the imbibition efficiency at this stage.Screened that when the concentration of surfactant I was 0.2%,the imbibition efficiency was the highest.It is believed that adding surfactants to reduce the interfacial tension to the level of 0.01 m N/m is the most beneficial for improving the imbibition efficiency of cores in the study area.The design simulates the real water huff-puff process,and it is concluded that the magnitude of the increase in imbibition efficiency by adding surfactant.It is believed that the addition of surfactants can effectively reduce the oil and water displacement resistance and accelerate the imbibition rate.Using CMG numerical simulation,the best parameter combination development plan is the injection volume 15000m~3,injection rate 500m~3/d,shut-in time 30 days,and liquid production rate 30m3/d.The main control factor affecting the oil production is the injection volume.The research results of this study could provide some reference for the efficient application of water huff-puff imbibition displacement in“three low”sandstone reservoirs.