Petrochina Company Limited

Hubei Huida High-tech Co., Ltd.

Borun High-tech Co., Ltd.

Yun Ling

Kun Wang

Zhe Li

Wei Gao

Wei Yin

Lei Shen

Xianwen Li

Yong Ding

Yajuan Wang

Xiaorui Liu

Xu Ma

Zhanguo Ma

Liang Ye

Yongfang Li

Jinying Zhang

Qianyun Zhao

Qiaorong Han

Changjing Zhou

Xinxing Ma

Yuanxiang Xiao

Man Bi

Hua Shi

Yanming Zhang

Huaqiang Shi

Mingfang He

Baochun Chen

Hongying Li

Ruifen Hao

Yonghong Gu

Guohui Su

Lizhu Chen

Yangming Hu

Shaowei Zhou

Xiaoyong Wen

Shusheng Li

Xuan'ang Lai

A method for preparing 3,3′-diaminobenzidine, the method comprising the following steps: subjecting 4,4′-biphenol and N,N-dimethylsulfamoyl chloride to an esterification reaction in a specified solvent at 40-70° C. to obtain 4,4′-biphenyl bis(N,N-dimethylaminosulfonate) as a first intermediate; subjecting the 4,4′-biphenyl bis(N,N-dimethylaminosulfonate) to a chlorination reaction with a chlorinating reagent under acidic conditions to obtain 3,3′-dichloro-4,4′-biphenyl bis(N,N-dimethylaminosulfonate) as a second intermediate; subjecting the second intermediate 3,3′-dichloro-4,4′-biphenyl bis(N,N-dimethylaminosulfonate) to an ammonolysis reaction with anammoniation reagent in the presence of a combined catalyst to obtain a crude product of 3,3′,4,4′-tetraaminobiphenyl, wherein the combined catalyst is a mixture of proline, a cuprous salt and a phase transfer catalyst; and subjecting the crude product of 3,3′,4,4′-tetraaminobiphenyl to a post-treatment to obtain a purified 3,3′,4,4′-tetraaminobiphenyl product. In the present invention, 4,4′-biphenol is used as a raw material, a brand-new synthesis route is used, the product purity is high, and pollution of three kinds of waste is reduced.

Method for preparing 3,3′-diaminobenzidine

The present invention discloses a method for lowering an oil pipe in a gas well without well-killing, a soluble bridge plug and a material preparation method thereof, wherein, the method comprises the steps of: lowering a bridge plug in a wellbore such that the bridge plug blocks the wellbore at a predetermined location in the wellbore; injecting water in the wellbore after the pressure in the wellbore has been relieved so as to replace gases in the wellbore; and lowering an oil pipe in the wellbore to the location of the bridge plug. The method for lowering an oil pipe in a gas well without well-killing, the soluble bridge plug and the material preparation method thereof provided in the present invention successfully solve the problem of high cost for lowering an oil pipe under pressure after a fracturing fluid has been injected into the casing.

Method for lowering oil pipe in gas well without well-killing, soluble bridge plug and material preparation method thereof

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Beijing, China

Yun Ling