A Mechanism And Applied Research On Intermittent Producing To Extra Low-permeability Reservoir In Xi Feng Oilfield

Intermittent producing defined as opening and closing the well periodically is to carry out the operation of opening and closing the well when dynamic liquid level reaches the corresponding depth.Not only can it save power and improve pump efficiency,but also do activate dead oil by forming pressure waves in the reservoir and change the distribution of oil saturation to increase oil production to some extent.This paper studies the low productivity and efficiency wells at the north of Bai Mazhong(also called Xi17)belonging to extra-low permeability reservoir in Xifeng oilfield and describes the necessity of intermittent producing on the basis of knowing the features of geology and production performance fully.The mechanism of increasing the production is explained from the microscopic and macroscopic perspectives and the charts for ? vs h and Q vs L are created based on the data measured on the spot,which confirm the threshold value.According to the pressure recovery testing,the empirical formula for determining the working system of intermittent producing is derived and built.By collating and analyzing the data of nearly 200 test wells in Xifeng Oilfield,the correlation between yield recovery rate and water content,pressure maintenance level,flow pressure,permeability,single well productivity and single well production.The master factors involve water content,flow pressure and single well productivity.Finally,three dynamic indexes(oil well output,water content,and flow pressure)of the typical well Xi31-37 put intermittent producing into effect are forecast and optimized by using numerical simulation combined with the law of pumping efficiency.The eighth project(shutdown 8 days,production 7days)is considered the optimum one.According to the economic evaluation results,the economic benefit brought by a reduction in cost is much greater than that of a higher yield in terms of the intermittent producing.