Vertical Subdivision Layer Stimulation Technology for Ultra-Deep and Super-Thick Tight Sandstone in Kuqa Piedmont

The Cretaceous system in Kuqa Piedmont of Tarim Oilfield is a super-deep and super-thick fractured tight sandstone with developed natural fractures and strong heterogeneity. The gas production profile test of stimulated wells shows that the conventional general stimulation of vertical thick reservoirs is not sufficient, and the production capacity is not completely released. In order to solve these problems, layered fracturing technology can be implemented for wells with large reservoir thicknesses and obvious interlayers, which can also enhance the performance of vertical stimulation. A set of fine identification methods for multi-scale fractures of near and far wells was established by using multi-logging data through engineering and geology integration research. Based on the relationship between lost circulation and production, a set of reservoir evaluation classification methods was established, which comprehensively considered the structural location, lost circulation in drilling, fracture development, mechanical activity, and other data. Through fine mechanical checking of double packer pipe string, expansion pipe was added, and the grain size of temporary plugging material was optimized, forming a soft and hard layered fracturing technology featuring “mechanical + temporary plugging”, thus realizing the highly efficient production of the super-thick reservoir. The technology was applied to 20 wells, and the production of a single well was increased from 6.7×10⁴ m³/d to 34.0×10⁴ m³/d after stimulation, with the production remarkably increasing by four times on average. The technology provides strong technical support for the efficient development of super-thick tight sandstone reservoirs.