Application and Study of New Supramolecular Temporary Plugging Technology in Secondary Stimulation and Productivity Enhancement of Gas Wells

A supramolecular temporary plugging agent has been developed specifically for the low-porosity, low-permeability, fractured sandstone reservoirs in the Kuqa foreland of the Tarim Basin, where hydraulic fracturing is required to sustain stable long-term production of wells. Unlike conventional temporary plugging agents— which are unable to effectively plug fractures of 6 mm or larger and tend to cause reservoir contamination—this newly developed agent offers superior plugging performance without harming the reservoir. In addition, conventional temporary plugging agents can only achieve an inter-layer diversion pump pressure increase of 6–7 MPa, whereas the supramolecular temporary plugging agent achieves diversion pump pressures of 9.7–11.1 MPa. Supramolecular materials are assembled through ternary combination relationships using the "bottom-up" approach of modern nanotechnology at the molecular level. Under ambient temperature conditions (20°C), the supramolecular temporary plugging agent exists as a low-viscosity liquid, facilitating injection. After being injected into the fracture, the agent undergoes a phase transition to form a solid-like supramolecular material as the temperature rises to a certain range (30–40°C for low-temperature systems; 80–100°C for high-temperature systems), This temporarily seals the fracture and diverts the fracturing fluid, leading to the formation of new fractures. With a further increase in temperature to 60–80°C (low-temperature systems) or 120–170°C (high-temperature systems), the material reverts to a liquid state and can be flowed back to the surface. Based on the performance experiments of supramolecular temporary plugging agents, simulation of the operational temperature field, and results from field applications, this technology represents a significant advancement over conventional fracture steering methods, simplifying the implementation of volumetric fracturing or fracture network fracturing (including acid fracturing). Compared with traditional granular or fiber-based temporary plugging technologies, supramolecular temporary plugging agents require simpler pumping equipment and achieve superior fracture plugging effectiveness. A single hydraulic fracturing operation can generate multiple oil and gas flow channels within the fractures, thereby attaining the intended effects of volumetric or fracture network fracturing. After completion, the agent undergoes automatic unblocking through thermally induced phase transitions, which causes no harm to the reservoir while significantly enhancing the productivity of individual wells. This technology has been applied in over 10 gas wells in front of Kuqa Mountain in Tarim Oilfield. Compared with conventional temporary plugging agents, the plugging pressure is about 50% higher, which enables fracture creation further away from the wellbore after diversion and results in superior production performance post-treatment. This technological achievement holds broad prospects for application and popularization, providing valuable reference for gas fields in the Kuqa Mountain foreland and other tight sandstone reservoirs.