The flowback fluid during oil acidizing operation process would directly enter the gathering and transportation system,resulting in deterioration or invalidation of conventional treatment agents,such as demulsifiers.The flowback fluids from the Chengdao Oilfield were divided into two types ，one is high mass concentration,the other is low mass concentration.The high mass concentration flowback fluid is transported back by the operating ships to the shore for further treatment,and the low mass concentration flowback fluid is directly discharged into the gathering and transportation system under the ground.The flowback cycle is long and affected by sea conditions. In order to reasonably estimate the amount of high mass concentration flowback fluid produced by crude oil dehydration process,this paper analyzes the factors affecting the oil⁃water separation of acidified flowback fluid.The volume of flowback fluid and indicators of water in two acidified oil wells were monitored,and thermal deposition of mixed flowback fluid and crude oil were tested. According to the demulsification effect and the water content of crude oil form the joint station, the quantified critical control index are listed as: the pH value of the water from the acidified oil well is higher than 6, the iron ion concentration is lower than 250 mg/L；and the auxiliary control index: the amount of backflow reaches 6 times higher than that of the acid liquid. An inspection method is proposed for the on⁃site operation of the flowback fluid discharging into the gathering and transportation system, properly reducing the flowback time without adding a new processing flow, which is beneficial to increase the oil well production rate and improve economic efficiency.

The treatment of acrylic plant biochemical pool wastewater by combined electrochemical oxidation and nano catalytic micro-electrolysis technology were studied.Using the national standard test methods to analyse four indicators which include COD,NH ₃-N,pH and chromaticity.The results show that when the dosage of NaClat 0.3% and current was 9 A and the cycle time was 3.5h,the concentration of COD reduced to 46 mg/L from 227 mg/L,its removal rate reached 79.7%.The concentration of NH ₃-N reduced to 9 mg/L from 117 mg/L,its removal rate reached 92.3%,chromaticity reduced to 4 times from 32 times,its removal rate reached 87.5%.Experiments show that the combined electrochemical oxidation and nano catalyticmicro-electrolysis technology in the field of organic wastewater treatment has broad application prospects.

The BP neura1 network and the tested gel points of the blend crude oil were studied. A prediction model based on the BP neura1 network was established to calculate the gel point of the blend crude oil. The back-propagation artificial neural network has the satisfactory nonlinear prediction ability. The gel points of the component crude oil and their proportions were taken as the input vector and the gel points of the blend crude oil as the output one. The relationship between the gel points of the blend crude oil and the component crude oil was researched. The results show that the gel point prediction model based on the BP neura1 network is better than other gel point prediction models. The maximum average deviation of the predicted gel point is only 0.128 °C and the average absolute deviation is 0.022 °C. 

he characteristics of restart pressure used in the crude oil pipeline shutdown and restart safety assessment were analyzed. It is pointed out that the maximum allowable incident pressure（MAIP）, but not the maximum allowable operation pressure（MAOP）, was more suitable for the safety assessment benchmarks of pipeline shutdown and restart. Referencing the MAIP and basing on the pressure parameters provided in Chinese standards, 1.1 times pipeline internal design pressure, 1.1 times pipe remaining strength and 1.1MAOP were respectively recommended as the safety assessment benchmarks for pipelines with no defects, detected defects and undetected defects. The results obtained in a case of a pipeline with undetected defects show that 1.1MAOP is more reasonable than MAOP as the safety assessment benchmarks of shutdown and restart for crude oil pipeline.