Optimization Study of Fracturing Length for Rhombus Inverse Nine-spot Diamond Reverse Well Pattern in Anisotropy Reservoirs

doi:10.19657/j.geoscience.1000-8527.2018.03.12

Abstract

Abstract:

Nine-point diamond reverse well pattern is widely applied in the development of low-permeability reservoirs, and the wells with hydraulic fracturing can significantly improve the oil recovery. The production wells with equal length of fractures, however, may cause non-uniform displacement. The impacts are more serious if the reservoir properties are inhomogeneous. The main focus of previous research is to study the effect of equal length fractured wells regarding to the nine-point diamond reverse well pattern, without the consideration of unequal length fractured wells. Consequently, we established a numerical simulation model based on parameters of a specific low-permeability inhomogeneous reservoir. Nine-point diamond reverse well pattern was used, and unequal fracture lengths were designed for each well. The anisotropic effects of permeability and fracture lengths on the water-flooding efficiency were analyzed in detail. The results indicate that the optimized fracture penetration ratios of corner wells decrease, and those of the edge wells increase with the increasing ratios of permeability in the x and y directions. When the permeability is uniform in the x and y directions, the influence of whether injection well is fractured or not on penetration ratios of corner wells is relatively small, compared to the influence on edge wells. Our results show that the development effect of nine-point diamond reverse well pattern in inhomogeneous low-permeability reservoirs will be boosted significantly by designing unequal length fractures. This has great significance on the design for fracturing of anisotropic low permeability reservoir and well pattern design.

Key words: anisotropy, low permeability reservoir, nine-point diamond reverse well pattern, fracturing, unequal fracture

CLC Number:

TE34

WANG Fushun, LIU Pengcheng, WANG Wenhuan, HAO Mingqiang, ZHUANG Yongtao. Optimization Study of Fracturing Length for Rhombus Inverse Nine-spot Diamond Reverse Well Pattern in Anisotropy Reservoirs[J]. Geoscience, 2018, 32(03): 547-553.

Figures/Tables 6

Fig.1 Sketch for the location of wells and fractures in simulation model

Fig.2 Plane distribution of remaining oil saturation with injection well fractured at different Kx:Ky

Fig.3 Relationship between oil recovery and fracture penetration ratio of the edge well at different Kx:Ky with injection well not fractured

Table 1 Optimization of fracture parameters with the injection well not fractured at different Kx:Ky

编号	K_x:K_y	角井裂缝优化穿透比	边井裂缝优化穿透比	生产6年综合含水率/%	采出程度/%
1	1:1	0.83	0.17	26.3	46.9
2	3:1	0.57	0.37	80.7	51.3
3	6:1	0.50	0.50	91.4	53.3
4	10:1	0.43	0.63	94.4	54.6

Fig.4 Relationship between oil recovery and fracture penetration ratio of the edge well at different Kx:Ky with injection well fractured

Table 2 Optimization of fracture parameters with the injection well fractured at different Kx:Ky

编号	K_x:K_y	角井裂缝优化穿透比	边井裂缝优化穿透比	生产6年综合含水率%	采出程度/%
1	1:1	0.77	0.43	87.8	52.3
2	3:1	0.63	0.63	94.6	55.8
3	6:1	0.57	0.70	96.5	57.8
4	10:1	0.30	0.90	97.1	59.1

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