Research Of Acidizing Effect Evaluation And Predicting Of Productivity Of Horizontal Wells

Horizontal well technology,as a high efficiency development technology in slowing water speed,increasing the injection ability and the swept volume,and reducing the pressure damage of formation,has been used more and more widely.In the process of drilling and completion of horizontal wells,drilling fluid and completion fluid need to contact the reservoir for long time in large area,forming a large area of pollution zone,so the damage of reservoir is more serious than vertical wells.Therefore,horizontal well also need to acidize to dredge the near wellbore flow channel,restore and enhance the productivity of oil and gas wells.The correct and effective forecast of horizontal well productivity after acidification is the key to the evaluation of the effect of oil and gas reservoir and the effect of acidizing stimulation.Evaluation of acidification effect and the calculation method of productivity of the horizontal wells after acidizing are studied in this paper.It provides the theoretical basis for acidizing technology of horizontal wells.First,the damage characteristics of horizontal wells are analyzed,and the calculation model of skin factor after acidizing of horizontal well is established.Then,by using power theory and mirror reflection principle,the coupling flow model of horizontal wellbore and reservoir is founded.With the coupling model corrected by the skin factor model,the model of productivity of horizontal well after acidification is also established.Finally,a program is written,and the model giving an example is calculated by using the method of numerical simulation.The sensitivity analysis of the horizontal well productivity after acidification is obtained.The permeability of pollution zone,the maximal distance of pollution and other factors on the impact of acidification effect are analyzed.