Temporary plugging agent technology in dense gas reservoir applications

 As the exploration and development of oil and gas resources deepens, the geological engineering complexities of tight gas reservoirs are increasingly prevalent. These include thick reservoirs, numerous thin interbeds, developed natural fractures, or uneven fracture extension, resulting in strong heterogeneity of the reservoir. Factors such as interwell interference and casing deformation complicate underground conditions, hindering the normal operation of downhole tools, affecting fracturing operations, and even leading to construction failures. Biodegradable temporary plugging agents address the shortcomings of mechanical stratification, effectively solving the problem of unstratifiable casing deformation. By plugging and relieving pressure, they achieve inter-cluster balance and in-seam expansion, effectively tackling the challenges of strong heterogeneity, numerous thin interbeds, and uneven fracture extension. These agents use biodegradable temporary plugging spheres or combine different particle sizes to create a tight sealing band at the fracture mouth and ends, forcing fluid redirection and creating new or branching fractures. Through "refined" transformation, they increase the complexity of fractures and the volume of transformation.

The degradable temporary plugging agent boasts easy operation, excellent temporary plugging performance, rapid degradation speed, and high construction success rate. Its enhanced production effects are remarkable, to some extent replacing complex processes like bridge plugging and jetting, simplifying on-site construction techniques, improving work efficiency, and reducing operational costs, thereby achieving cost reduction and efficiency increase. Field applications indicate a significant increase in production after temporary plugging modification. The temporary plugging materials can be hydrolyzed into non-polluting small molecules after construction, which are safely discharged into the formation, preventing reservoir damage, and aligning with the current green and environmental-friendly mining concept.

Through indoor improvement research and development, a series of high-intensity, wide-temperature range, dissolvable, and biodegradable temporary blocking materials have been developed, forming two commonly used temporary blocking products: biodegradable temporary blocking balls and high-intensity dissolvable temporary blocking agents. The biodegradable temporary blocking balls, with diameters ranging from 5 to 23 mm, force the subsequent working fluid to shift layers by sealing the perforation boreholes at the fracture. They can withstand pressures above 70 MPa, have a temperature resistance of 50 to 180°C, and the dissolution time is adjustable. The high-intensity dissolvable temporary blocking agents, with large particles entering the fractures to form a filter cake bridge plug at the fracture, redirect the subsequent working fluid into high-stress areas or new fracture layers, temporarily blocking the fracture. The small particles seal the fracture internally, with diameters ranging from 1 to 8 mm, capable of withstanding pressures of up to 40 MPa, having a temperature resistance of 160°C, and with adjustable dissolution time.
In-field operations can utilize one or more degradable temporary plugging materials or customized products to achieve转向 within or at the junction, forming multi-segmented or long-segmented channels with effective flow guidance. This is applicable for reservoir modification under various stratigraphic conditions, suitable for thin interbedded reservoirs with strong vertical heterogeneity and for low-producing wells with repeated fracturing in old wells. It is significant in increasing the modified volume.