Study On Evaluation Of Effectiveness Of Auxiliary Anode And Long - Acting Reference Electrode For Tarim Oil And Gas Pipeline

In2014, the Tarim Oilfield oil and gas production reached24.67million tons equivalent, is an important guarantee of " west-east natural gas" and other oil and gas energy projects.27oil and gas pipelines owned total2394.91km, catchment harsh climatic conditions, soil environment is complex, coupled with a long pipe in service time, so reasonable and effective cathodic protection of the pipeline is to determine the basic conditions for normal operation. Oilfield impressed current cathodic protection method, the operation of various types of equipment failures and problems highlighted part of the pipeline is still in the under-protected or over-protected.27oil and gas pipeline along the Tarim Oilfield were set between41cathodic protection, quantity and widely distributed, leading to high management and maintenance costs, low efficiency. Therefore, to ensure the efficient operation of27oil and gas pipelines impressed current cathodic protection system, it is necessary for an important part of the system-auxiliary anodes and reference electrodes to carry out long-term effectiveness of the evaluation.Evaluate the effectiveness of the service is the auxiliary anode and the continued use of long-term reference electrode, and how to continue to use quantitative analysis. It can determine the effectiveness of the evaluation carried out its health and factors leading to the failure to help put forward the management and maintenance measures, but also for the Tarim Oilfield auxiliary anode and long-term oil and gas pipeline construction reference electrode provides a theoretical basis and improvement support and technology.The main contents and results are as follows:(1) Tarim Oilfield auxiliary anode27oil and gas pipelines and long-term reference electrode on-site investigation, sampling and tested along the pipeline cathodic protection of the environment among41soil properties, mastered the27oil and gas pipelines Status impressed current cathodic protection. According to the requirements of the relevant standards, test the anode grounding resistance, the parameter index anode bed with the vertical distance pipeline protection, pipeline polarization potentials. Combination of historical accident and failure analysis, master the auxiliary anodes and reference electrodes of the current long-term service conditions;(2) Based on a long-term auxiliary anode and reference electrode design principles, working conditions and the current service status, long-term analysis of the auxiliary anode and reference electrode main failure ratio factor. Integrated auxiliary anode high ground resistance, long-term reference electrode potential error circumstances larger cathodic protection between the anode bed determined to be protected pipeline vertical distance, long-term reference electrode ion mobility degree factors than as an auxiliary long-term effectiveness of the anode and the reference electrode quantifiable indicators;(3) Quantifiable indicators for the effectiveness of using the pipeline cathodic protection potential distribution mathematical model analysis showed that:the auxiliary anode distance is farther pipeline protection, protection potential distribution on smaller. Because of the potential pipeline protection potential of a metal and dielectric anode potential of two parts, the distance from the anode classified as short-range, intermediate and long-range areas, carry out research pipeline cathodic protection potential distribution formula, the establishment of anode location optimization model to calculate the anode Best location range. According to a long-term reference electrode and the exchange of ions in the soil environment than ion transport equations are derived to calculate the soil environment typical of long-term reference electrode ion level migrate through a nine-month long-term reference electrode embedded test It is verified, and gives a long-term reference electrode test maintenance period;(4) According to relevant standards, with27oil and gas pipelines impressed current cathodic protection current situation, select the auxiliary anode12total evaluation, evaluation of long-term co-reference electrode9, in accordance with the principle of Ⅰ, Ⅱ, Ⅲ grade division, based on improved AHP methods and computer program MATLAB, reasonably determine the weight of each evaluation index weight coefficient. The establishment of a long-acting auxiliary anode and reference Method for Evaluating the effectiveness electrode obtained between41auxiliary anode cathodic protection and long-term effectiveness of the extent of the reference electrode, and the results in line with the actual situation;(5) Evaluate the effectiveness of the use of the established system, auxiliary anode27for the Tarim oil field oil and gas pipelines and long-term reference electrode failure condition proposed including the replacement of the auxiliary anode and the long-term reference electrode, a reasonable choice of long-acting auxiliary anode and reference electrode type, increasing the anode and deep anode cable connector, water drop resistance and other corrective measures, including recommendations and management. According to the Tarim Oilfield auxiliary anode27oil and gas pipelines and rules and characteristics of long-term failure of the reference electrode, it made specific and long-acting auxiliary anode electrode reference design proposals for the Tarim oil field oil and gas pipelines and long-acting auxiliary anode reference electrode construction and improvement of a theoretical basis and technical support.