Traditional foam hydraulic fracturing fluids used guar crosslinking technology. However, major production problems, such as high friction and difficulty to accurately control the cross-linking time, have influenced the large-scale application of cross-linked guar foam fracturing fluids. In this study, we developed a novel non-cross-linked foam fracturing fluid using a series of polymers synthesized with acrylamide and hexadecyl trimethylallyl ammonium chloride as monomers and improved the stability of foam by forming structures in solution through association. The results showed that the hydrophobic groups were the key factors that affect the foam stability, and the hydrolysis degree had a significant effect on the elasticity of the polymer solution. The model association polymer with 0.75% hydrophobic group content and 56% hydrolytic degree was optimal. The stability of our proposed foam was comparable to that of the cross-linked guar gum foam. The adsorption of associating polymers on the gas and water interface resulted in a high-stability foam. Our study demonstrates a new avenue to develop high-stability foams to satisfy the current hydraulic fracturing scheme.
This paper takes the deep ore body of Yunnan Phosphate Group Co. Ltd, the largest open-pit chemical mining enterprise in China, as the research background, and systematically introduces the technical problems recognised by many Chinese researchers in the past eight years on the open-pit to underground mining of gently inclined thin to medium-thick ore bodies with a soft interlayer. It shows that the mining of open-pit transferred to underground is a complex engineering system, and the underground stope surrounding rock and overlying strata present a nonlinear failure process. Through mining process innovation, mining method innovation and improvement, research was undertaken on new processes and technologies for phosphorus mining under complex conditions. The relevant research results not only have important economic value and academic significance for Yunnan Phosphate Group Co. Ltd. but also have important guidance and impetus to the exploitation of a large number of similar phosphate resources in China.
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