Research On Plug Removal Technique In Low Permeabile Oil Field

Development of low-permeability reservoir is a quite difficult problem,but with the development of petroleum exploration and production technologies,the development in the low permeable reservoirs has been paid more attention in recent years.This is important for stabilization of oil production in China.In low permeabile oil field,high content of clay mineral in low permeability formation cause serious formation damage.Injection wells have problems of little hygroscope thickness and low hygroscope capacity.On the basis of the sensitivity study of low permeability formation and the research on damage characterization of low permeabile oil field, this paper has analyzed the factors that cause these damages ,and developed a new plug removal technique named XJJ-01.The main results and contributions of this paper are as follows:1,On the basis of analysis on the components and characterics of clay mineral, together with the reseach on sensitivity experiments and study on damage factors of low permeability formation,we summarized sensitivity characterization and damage characterization,which provided the foundation for the research on the plug removal technique.Based on basic structure, connected with hydrous expansion, flocculate and disintegration, the potential methods by which clay mineral does damage to reservoir is analyzed theoretically.Through much analysis on clay mineral, we conclude that the clay minerals in low permeabile formation are mainly smectite,illite,kaolinite and chlorite.These clay minerais, due to different structures, are divided into clay minerai of water sensitivity,clay mineral of velocity sensitivity and clay mineral of acid sensitivity.2,Performance of XJJ-01 has been measured by experiments,the experiments indicate that this plug removal technique has a remarkable characterization of low damage to reservoir,has powerful ability to dissolute clay minerals,not to cause particle migration and expansion of clay mineral,and not to cause new damage to low permeable reservoir. It can increase the penetrability of the matrix and logged matric to 98% and 150% respectively.XJJ-01 has good characteristics of retarded acid,its effective distance is long,its injection volume is small,the cost of using XJJ-01 is low,field experiments of this technique are simple and the effective period of XJJ-01 is long.3,By theoretical calculation, parameters of injection pressure, maximum discharge capacity, injection volume have been decided;and it's field application technique has been determined. 4,18 wells have been applied with this technique.Total results, single well analysis and economic benefit have been conducted which ensures the feasibility of this technology.This technique has a broad foreground of application.