Complex Dynamics of Hydraulic Fracture Network in Ultra‐Deep Fractured Sandstone Reservoirs in Tarim Oilfield, China

ABSTRACT The fractured sandstone reservoirs, exemplified by the Kuqa depression, are rare ultra‐deep gas reservoirs found worldwide, and constitute the primary natural gas reserves of the Tarim oilfield, China. The target reservoir exhibits low matrix porosity and permeability, but is distinguished by well‐developed natural fractures. Hydraulic fracturing is a crucial method for achieving its effective development. Field practices have demonstrated that the properties of natural fracture groups (NFGs) are significant controlling factors influencing gas well production in this region. However, the existing comprehension of how NFG properties influence hydraulic fracturing outcomes remains obscure. Therefore, taking the case of ultra‐deep fractured sandstone from Well A located in the Kuqa depression, this paper constructs NFGs and subsequently incorporates it into a three‐dimensional fracturing model. Based on this integration, we have developed a comprehensive and fully‐coupled hydraulic‐mechanical numerical model tailored for simulating network fracturing. The reliability of the simulation results is verified using microseismic monitoring data and on‐site injection pressure. Furthermore, the propagation dynamics of hydraulic fracture network in fractured formations composed of single or conjugate orthogonal NFG(s) are analyzed, respectively. The effects of crucial parameters, including natural fracture density, strike, aspect ratio, and injection rate, are explored. The study uncovers that high natural fracture density, low strike, and large injection rate favor the formation of complex hydraulic fracture networks. By selecting formations with large natural fracture strike and suitable aspect ratios as fracturing sweet spots, deep‐penetration stimulation is effectively achieved.