Well Pattern Design Of CO₂ Huff-n-puff Of Volume Fractured Horizontal Well In Tight Oil Reservoir

There are abundant tight oil resources in our country,which are lack of natural energy.On volume fractured horizontal wells by natural depletion,the production declines fast,and the recovery is very low.After large-scale fracturing,it’s too easy to break through for water flooding to produce the oil in the matrix.Therefore it’s necessary to search for effective ways to supplement energy in tight oil resevoir.Based on the tight oil reservoir properties of M block in Maling oilfield,CO₂huff-n-puff,natural depletion and water huff-n-puff are analyzed using the method of reservoir engineering combined numerical modeling.The results show that CO₂huff-n-puff can significantly enlarge the effective use of range,which is feasible in tight oil reservoir development.Adopting the method of range analysis and grey correlation analysis,the influence of CO₂ huff-n-puff parameters is analyzed.The results indicate that bottom hole pressure and number of cycle influence most in CO₂ huff-n-puff,followed by injection quantity,injection rate,and soaking time.The optimization result of CO₂ huff-n-puff is bottom hole pressure of 5 MPa,3 cycles,injection quantity of11520t,injection rate of 12t/h,and soaking time of 60 days.On equally spaced orthogonal fracture condition,the impact of the number of fracture,fracture half-length,and fracture network pattern on CO₂ huff-n-puff effect is researched.As for the volume fractured horizontal well,which is 1200m long and 150m fracture half-length,9 stages4 clusters and the fracture network pattern of fusiform is the best choice.After the parameters of the fracture network are optimized,the well spacing and row spacing are optimized in parallel pattern and staggered pattern,and it turns out that staggered pattern can produce oil from bigger scope.The best well spacing and row spacing are600m and 300m,in which the recovery can be increased by 8.8%compared to natural depletion.