| The following problems exist in Block A of Shengli Oilfield: after multiple steam stimulation,the cycle effect becomes worse,the production decline is fast,the affected area is limited,and the recovery degree is low.Due to the high viscosity of heavy oil,the water flooding effect is poor and the recovery factor is low.Due to the influence of reservoir thickness,when the reservoir thickness is thin,the heat loss of steam injection production in the surrounding rock is great,so thermal oil production method is not suitable for this kind of reservoir.Therefore,for heavy oil reservoirs with thin reservoirs and active edge and bottom water,chemical viscosity reduction composite flooding technology combining polymer and water-soluble viscosity reducer has been widely recognized.Block A of Shengli Oilfield as an example,the paper aimed at the problems arising from the development process of block steam stimulation,the chemical viscosity core displacement experiment method,composite flooding in further study of polymer increased displacement sweep area and reduce the viscosity of crude oil viscosity agent to improve oil recovery mechanism,combined with the numerical simulation model in Block A of Shengli Oilfield,key parameter optimization for chemical compound flooding,In order to develop the chemical viscosity reduction composite flooding technology research.(1)The experimental part of this paper firstly characterized the developed viscosity reducer:(1)The higher the concentration of viscosity reducer,the better the viscosity reduction effect,the concentration is greater than 0.3% has obvious viscosity reduction effect;(2)When the salinity is10000mg/L,the viscosity of the oil/water system decreases to less than 20 m Pa·s.(3)When the temperature is 70?,the viscosity of the oil/water system is reduced to less than 20 m Pa·s.The viscosity reducer is suitable for reservoir conditions.Then the hydrophobic association polymer and common polyacrylamide polymers were optimized.(1)At the same concentration,hydrophobic association polymer has better viscosifying effect;(2)The hydrophobic association polymer has good salt resistance when the salinity increases;(3)In the thermal stability evaluation,the hydrophobic association polymer can maintain good performance at reservoir temperature;Finally,the hydrophobic association polymer was selected as the displacement agent.Indoor core physical simulation displacement experiment,according to the displacement characteristics of polymer and viscosity agent explain oil displacement mechanism of polymer slug and viscosity of composite flooding agent injection sequence were compared and concluded that the first note polymer viscosity agent injection effect is better,the use of flat intuitive visualization experiments show the first note the synergies of viscosity agent after polymer flooding effect.(2)Numerical simulation: Taking Block A of Shengli Oilfield as an example,a component numerical simulation model was established based on geological data and basic experimental data,and historical fitting was carried out;The actual model was used to verify that the effect of polymer injection followed by viscosity reducing agent was better,and the parameters such as slug size,injection agent ratio,agent concentration and injection speed were optimized.The optimal parameters were obtained,including slug size 0.6PV,injection agent ratio 3:2,polymer concentration 3000mg/L,viscosity reducing agent concentration 1% and injection speed0.075PV/a.It provides a theoretical basis for chemical flooding recovery of similar heavy oil reservoirs. |
PDF Full Text Request