Pressure Transient Analysis of Fractured Horizontal Wells in Multiple-Well Pads With Complex Fractures Using a New Numerical Model

Abstract The technology of multi-stage, multi-well pad fracturing is an effective way to increase the stimulated volume and recoverable reserves in shale reservoirs. During the fracturing treatments, there are common phenomena of well interferences from the multi-well pad. However, there still lacks an understanding on the transient behaviors of well interferences, which is harm for applications of well testing to analyze the parent-child interactions and to evaluate the fracture parameters quantificationally. To narrow this gap, pressure transient behaviors of fractured horizontal wells with secondary fractures and well interferences are studied by a numerical pad-well model, based on a discrete fracture model (DFM) and unstructured PEBI grid system. First, the pressure transient solutions of fractured horizontal wells with secondary fractures and well interferences have been demonstrated by model verifications. The results show that the flow regime of interference effects caused by parent-child interactions are more obvious, with a larger child-well production, a smaller well spacing, and a larger hydraulic-fracture angle. The well interferences are also stronger when the child well has more secondary fractures, longer secondary fractures, and higher fracture conductivity, as the pressure drop caused by child well will propagate more quickly. Once the complex fracture networks have developed within the multi-well pad, the interactions between parent and child well will be weaker with the increase in area and conductivity of fracture networks. By comparison, the pressure transient behaviors of Parent well are remarkably affected by Child-well production rate, well spacing as well as connectivity degree. However, the angle, length, number, and conductivity of secondary fracture have weaker impacts on the pressure transient behaviors of Parent well. This work provides a meaningful way to understand the pressure transient behaviors and to evaluate the fracture parameters of multi-stage, multi-well pads.