Temporary Plugging Agent Technology in Dense Gas Reservoir Application

 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 casing deformation that prevents stratification. They achieve inter-cluster balance and in-seam expansion by plugging and relieving pressure, thereby addressing the challenges of strong heterogeneity, numerous thin interbeds, and uneven fracture extension. By using biodegradable temporary plugging spheres or combining different particle sizes of plugging agents, they 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 ease of operation, excellent temporary plugging performance, rapid degradation speed, and high construction success rate. Its increased production effects are significant, to some extent replacing complex processes like bridge plugging and jetting, simplifying on-site construction techniques, enhancing operational efficiency, and reducing costs, thereby achieving cost reduction and efficiency improvement. Field applications show that the increased production after temporary plugging is remarkable. The temporary plugging material can be hydrolyzed into non-polluting small molecules and cleanly排出 from the formation after construction, preventing reservoir damage and aligning with the current green and environmental-friendly extraction concept.

Through indoor improvement and research and development, a series of environmentally friendly temporary plugging materials with high strength, wide temperature range, solubility, and biodegradability have been developed, forming two commonly used temporary plugging products: biodegradable plugging balls and high-strength soluble temporary plugging agents. The biodegradable plugging balls, with diameters ranging from 5 to 23 mm, force the subsequent work fluid to shift layers by sealing the perforation boreholes at the fracture, with a pressure-bearing capacity over 70 MPa and a temperature resistance of 50 to 180°C, with adjustable dissolution time. The high-strength soluble temporary plugging agent has large particles that enter the fractures, forming a filter cake bridge plug at the fracture, diverting the subsequent work fluid into high-stress areas or new fracture layers for temporary plugging, while small particles seal the inside of the fracture. The small particles have diameters ranging from 1 to 8 mm, a pressure-bearing capacity of 40 MPa, a temperature resistance of 160°C, and adjustable dissolution time.
In the field, one or more degradable temporary plugging materials or customized products can be utilized to achieve turning at the wellbore or within the formation, creating multi-segmented or long-segmented wells with effective flow guidance capabilities. This is suitable for reservoir modification under various stratigraphic conditions, including thin interbedded formations with strong vertical heterogeneity and low-producing wells with repeated fracturing. It is of great significance in increasing the modified volume.