3D Dynamic Stress Evolution of the Continental Shale Oil Reservoirs
Sand-shale interbedding is a significant geology feature of continental shale reservoirs in China.Due to the great difference of porosity,permeability and mechanical properties among different layers,the two-dimensional model cannot provide accurate guidance for shale reservoir development.According to the geology feature of continental shale reservoirs,a fully coupled mathematic model coupling solid deformation and fluid flow is proposed.The difference of stress sensitivity among different layers is also considered in this model.The stress evolution in a single well and multi-wells production process is investigated through numerical simulation.The simulation results show that:when refracturing is needed for the production well,the optimal refracturing locations are at the middle of the horizontal wellbore.The length of the optimal well section for refracturing should is related to the production time.With the longer production time,the length of optimal well section for refracturing is shorter.When taking the overall development efficiency of the reservoir as the goal,the well location should be designed in different layers,so that the well spacing can be reduced and the overall oil recovery of the reservoir can be increased without the interference between wells.To achieve better overall exploitation efficiency,when we design the well locations in different layers,there should be a specified horizontal distance among different wells,and the specified horizontal distance is different in different layers.The model established in this paper provides technical support for the design of three-dimensional well distribution,infill well and refracturing of shale oil reservoirs.