| Proppant in hydraulic fracturing technology occupies a pivotal position,but the proppant have commercial applications are crushing rate is high,the fracture conductivity of poor,pollution,high price,so the preparation of low cost,excellent performance of proppant has become a research hotspot.Polyurethane is a kind of multi-purpose synthetic resin with various forms.It has many characteristics,such as rich variety of raw materials,many combinations of formulations,and wide range of product forms and applications.In this paper,quartz sand was used as substrate,polyurethane resin was used as coating agent to coat quartz sand,polyurethane resin coating proppant was obtained and its properties were characterized.The specific research contents are described as follows:In the first chapter,summarize the hydraulic fracturing technology in literature review.The main role of proppant in hydraulic fracturing technology is to support the fractures formed by hydraulic fracturing,so as to facilitate the transportation of petroleum and natural gas.At present,commercial proppant is mainly composed of three main categories: natural quartz sand proppant,ceramic proppant and resin coating proppant.The research status of proppant is summarized,and their advantages and disadvantages are compared.The development process and characteristics of polyurethane resin are briefly introduced.In the end,the purpose and significance of this study were put forward in this paper.The second chapter discusses the preparation of polyurethane,the technology of coating,the coating of quartz sand by waterborne polyurethane,and the performance test of the coating proppant samples.The effects of isocyanate index,polyol type,temperature of quartz sand coating and the amount of waterborne polyurethane on the performance of proppant were studied.The performance of proppant was evaluated by characterizing volume density,acid solubility of proppant,and burning loss rate and the crushing rate under the closure pressure of 69 MPa.The solubility of proppant by waterborne polyurethane coating is about 4%.The crushing rate under the closure pressure of 69 MPa is about 30%,while the acid solubility of quartz sand and the crushing rate under the closure pressure of 69 MPa are 4.34% and 35.57%,respectively.The experimental results show that the waterborne polyurethane is not suitable for the preparation of coating proppant.The third chapter,one pot method to prepare polyurethane coating proppant,the polyol and isocyanate component of the feeding sequence,coating temperature,polyol type,isocyanate type,isocyanate index,curing agent and its dosage,the dosage of silane coupling agent,resin dosage,and the process route for the preparation of optimized polyurethane coating proppant.The performance of proppant was evaluated by characterizing volume density,acid solubility of proppant,and the crushing rate under the closure pressure of 69 MPa,and burning loss rate.The acid solubility of the polyurethane coated proppant is 2.53%,the crushing rate under the closure pressure of 69 MPa is 1.38%,the roundness and the sphericity are 0.85,and the turbidity is 13.3 NTU.These performances are higher than the requirements of the standard SY/T 5108-2014 of the People's Republic of China petroleum and natural gas industry.In the fourth chapter,phenolic resin modified polyurethane resin coating proppant was modified,including the order of phenolic resin,the type of phenolic resin,the proportion of phenolic resin and polyurethane resin,and the total amount of phenolic resin/polyurethane resin.Through the discussion of experimental conditions,it was found that the addition of phenolic resin reduced the acid solubility of polyurethane coated proppant from 2.53% to 2%,and the crushing rate under the closure pressure of 69 MPa decreased from 1.38% to 0.7%.The fifth chapter summarizes the content of the full text.And some recommendations of this research is given for further development. |
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