| The test of steam assisted gravity drainage(hereinafter referred to as SAGD)was carried out in Fengcheng oilfield in 2008 and successfully industrialized in 2012.By 2020,188 well groups have been pumped into production by Machine.And it has produced an annual oil output of more than 1 million tons,all of them use high-temperature,largedisplacement rod pump lifting technology.The Fengcheng SAGD horizontal well oil reservoir is shallow in burial depth and large in wellbore curvature,the actual 、drilling trajectory changed frequently,and the well trajectory was not smooth.The same configuration is adopted in the same block,without considering the difference of well trajectory and production conditions.The number of pump stuck work over caused by rod column eccentric wear accounts for more than 76%.Affected production time 34.8 days a well.The impact of annual oil production for pump stuck work over is 15200 tons.Meanwhile,due to the production conditions of high temperature and high pressure,the polished rod is affected by acid gas,produced fluid and the internal stress of the rod column during operation,the polished rod is corroded and mechanically damaged,the corrosion rate of the polished rod is as high as 81%,which affects the normal production.Therefore,SAGD development urgently needs to explore a set of high-efficiency sucker rod matching process,which can improve the production rate of oil wells and reduce the development cost.Based on the problems in SAGD production technology,the dissertation deeply analyzes the eccentric wear and corrosion mechanism of SAGD oil well rods from the aspects of formation fluid properties,weighted rod size and running nodes,wellbore drilling trajectory data,and production conditions.Based on Mechanism Analysis and cognition,The stress of the rod string is analyzed by using the differential element method,combined with the influence of actual drilling trajectory on the stress of rod string,iterates the actual drilling trajectory data and establishes a model through the calculus theory,and then calculates the stress of any node of rod string,obtains the neutral point position of different rod string combinations,optimizes the configuration length and strength check of rod string,and predicts the instability bending range,Finally,the evaluation and design method of SAGD sucker rod string based on the actual drilling trajectory of the well is formed.Aiming at the rod column corrosion,the corrosion mechanism research based on the properties of wellbore fluid was carried out,so as to optimize the anti-corrosion process of rod column,and the problem of bare rod corrosion shrinkage was effectively solved.Through project research,SAGD is equipped with a larger deflection as standard Φ38mm weighting rod,the consumption is reduced by 41.7%.The rod string optimization is implemented in combination with the "one well one policy" of well trajectory.The well trajectory is irregular,and the down hole pump is connected in series for production.Combined with the research results of rod string corrosion mechanism,the chromium plated anti-corrosion polished rod is optimized.After optimization,the comprehensive eccentric wear rate of rod and column decreased from 64.7% to 13.1%,and the proportion of bare rod corrosion and diameter reduction decreased from 81% to 8.9%.The research results were implemented for 89 wells on site,and the economic benefit was 30.2 million yuan.The cost reduction and efficiency increase of oil field development were realized,which was conducive to the long-term high and stable production of SAGD,it provides support for the popularization and industrial application of Fengcheng super-heavy oil development technology,and has reference significance for down hole rod lifting in oil reservoir development using SAGD technology in china and abroad. |
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