In the field of oil and natural gas exploration, fracturing temporary plugging agents play a crucial role. Especially in the turn-around fracturing technology, it can achieve temporary blocking, thus creating good conditions for subsequent fracturing operations.
Temporary plugging agents are divided into water-soluble and oil-soluble types in the industry. Among them, water-soluble temporary plugging agents have become the mainstream due to their wide applicability in various construction scenarios. There are many types of them, such as particles, pellets, and gel plugs and their compounds. The chemical composition includes various cross-linked or non-cross-linked polymer polymers.
At present, the mainstream degradable materials in the market are mainly polylactic acid (PLA), polybutylene succinate adipate (PBAT), etc. These materials can meet the requirements in terms of mechanics and are made into various shaped products such as fiber-like materials and fracturing plug balls, with a certain market scale.
However, research shows that after the temporary plugging operation is completed, it is difficult for the temporary plugging agent to be completely removed from the formation and there will be residues. This may permanently reduce the formation permeability. In some cases, the formation permeability can be reduced by -5% to -40%. Temporary plugging agent manufacturers or researchers often regard solubility as a comprehensive performance rather than a characterization from the perspective of chemical reactions and applications. They do not study the final reaction products with water from the perspective of chemistry and applications. For example, by mixing temporary plugging agents with formation water at different solid-liquid mass ratios and measuring the water solubility rate after being placed at 20°C, 40°C, 60°C, and 80°C for 8 hours and 16 hours.
Polyglycolic acid (PGA) as a new product has unique advantages. It has good quality. The tensile strength and bending strength are better than those of traditional engineering plastics such as PEK, PA, and POM. It is a high-quality engineering material and has been widely used to make high-strength disposable non-metallic tools. The fracturing balls and bridge plugs produced by it can meet the pressure-bearing requirements of 70 MPa and above. More importantly, PGA has good degradability and does not require mineralization degree. It is not affected by the concentration of the medium and has the same degradation rate in pure water and various salt waters. In particular, it is not affected by various chemical additives in the same liquid.
At present, in the North American market, MAGNUM Company and KREHA Company are mainly able to provide PGA material plug balls and bridge plugs. The raw materials all come from KUREA Company. The PA temporary plugging agent products launched by KUEHA Company are made into fiber and particle products. However, due to production capacity and cost factors, PA temporary plugging agents have not been widely used in the market and have not been widely used. Compared with PLA (mainly composed of various products), applications of such products are more common. Here, it is called on Chinese manufacturers to expand the production capacity of PGA to improve the performance of fracturing temporary plugging agents while reducing prices. Only after Chinese manufacturers clarify the basic principles and application markets can they achieve large-scale reproduction and provide better temporary plugging agent products for the oil and natural gas exploration field.
In addition, in the application of temporary plugging agents, knot temporary plugging agents and plugging balls are also relatively common forms. Knot temporary plugging agents can achieve temporary blocking effects through specific designs and operations; plugging balls can form blockages at specific locations to ensure the smooth progress of fracturing operations.