Influence of rock mechanics characteristics on fracturing and development strategies in the Zhengzhuang Block

The rock mechanical parameters of coal reservoirs play an important role in controlling the formation and evolution of natural fractures and the propagation of artificial fractures, and are the key factors affecting the fracturing transformation of coal reservoirs. In order to clarify the characteristics of rock mechanical parameters and the development law of fracturing fractures in Zhengzhuang Block, and realize the efficient transformation and development of coal reservoirs, a longitudinal and transverse wave conversion model was established based on array acoustic logging data, a dynamic and static rock mechanical parameter conversion model was established based on rock mechanical parameter tests and logging calculations, and the distribution law of rock mechanical parameters in Zhengzhuang Block was calculated by using conventional logging data such as acoustic time difference and density. On this basis, the FrSmart fracturing simulation software was used to establish the geomechanical models of horizontal wells in different well areas in the Zhengzhuang Block, and the fracturing simulation was carried out to explore the influence of rock mechanical parameters and fracturing scale on the fracture morphology, and propose differentiated development strategies for different well areas. The results show that the static Young’s modulus of Zhengzhuang Block is between 0.28−1.45 GPa, the average value is 0.95 GPa, the static Poisson’s ratio is 0.31−0.34, and the average value is 0.32, and the overall distribution is uneven. With the continuous increase of Young’s modulus and the decrease of Poisson’s ratio in coal reservoirs, the length of fracturing fractures decreases gradually, and the width of fracturing fractures gradually increases. There is a positive correlation between fracture length and fracture width and fracture scale, and increasing the amount of fracturing fluid and sand can effectively increase the fracture length and width and increase the fracture volume. With the increase of construction displacement, the length, width and volume of fractures were greatly increased. The pilot test of large-scale and large-displacement fracturing was carried out in the northern part of the Zhengzhuang Block, and the fracture monitoring results showed that the average fracture length was more than 400 m, the fracture width was more than 40 m, and the average volume of single reservoir reconstruction was 170×104 m3, and the transformation effect was increased by 580% compared with the past. In the subsequent development process, it is recommended to use large scale and high displacement fracturing in the northern well area of Zhengzhuang Block, with an optimal well spacing of 320 m; It is recommended to use a moderate fracturing scale for the renovation of the central and northern well areas, with an optimal well spacing of 300 m; It is recommended to use medium scale fracturing in the southwestern well area, with an optimal well spacing of 260 m.