Waterless fracturing fluid with low carbon hydrocarbon as base fluid for unconventional reservoirs

As the conventional fracturing fluids are not good for stimulation of unconventional reservoirs and the conventional oil-based fracturing fluids crosslink slowly, a ferric-complex cross-linking agent that cross-links fast with dialkyl phosphate ester was prepared and the fracturing fluid systems for the unconventional reservoirs were obtained. The main influencing factors on the properties of the cross-linking agent were analyzed and optimized, and then the ferric-complex cross-linking agent was prepared based on the optimizing results and its performance was evaluated. The optimizing and evaluating results show that: The ferric-complex cross-linking agent with excellent performance can be obtained in the condition that the content of cross-linking promoting agent is 5%, the content of ethylene glycol is between 8% and 10%, and the complexing agent is L-5 with content of 10%. The ferric-complex cross-linking agent has better performance than ferric sulfate and aluminium sulfate. It is found that the crosslinking slows down with the growth of carbon chain when using different base fluids. The fracturing fluid systems with low carbon hydrocarbon (such as LPG) as base fluid, dialkyl phosphate ester as gelling agent and ferric complex as cross-linking agent are developed, and all of them have excellent crosslinking performance and are suitable for unconventional reservoirs.