Fracturing With Low Molecular Weight Of Modified Guar Gum And Its Performance Evaluation

Although low molecular guar gum has good performance of water-solubility, it has defects of slow swelling and hydration,slow dissolve speed,uncontrollable viscosity and bio-degradation. All the defects influence the application of guar gum, so the paper modified guar gum for the purpose of enlarge applied range.This paper studied the effects of three modified groups on low molecular guar gum. In this paper, a cation etherifying agent was prepared, which had the same carbon-chain structure as sodium chloroacetate (car boxyl etherifying agent) and chloroacetic acid sodium(sulfo group etherifying agent). The low molecular guar gum was modified by the three etherifying agents, and three low molecular guar gums were prepared.The three modified guar gums and original guar gum were compared in this paper, investigated the different temperature resistance performance and gel-breaking performance and content of insoluble mater. The results showed cation modified could raise the temperature resistance performance, while sulfonation and carboxylation were bad for temperature resistance performance. The three modifications couldn’t remarkable influence the gel-breaking performance and content of insoluble mater. The experimental results showed the higher cation substituting degree better thermostability was. The modified low molecular guar gum had stronger system strength at high temperature.The low molecular cation guar gum fracturing fluid prescription was gained by experiments of agent selection and compatibility. The performance evaluation experimental results showed this fracturing fluid had good rheological characteristic. It was good for bracing layer and sending proppant to proper location. Good fluid loss control ability and few content of residue could reduce harm to layer.