Research on hydrajet fracturing mechanisms and technologies

Hydrajet fracturing,which integrates perforation,fracturing,and isolation,is a new stimulation technology for horizontal or vertical wells in low permeability reservoirs.It is feasible and effective for fracturing stimulation in low permeability reservoirs.This paper introduces the mechanisms of hydrajet perforation and hydrajet fracturing control,analyzing the factors that influence hydrajet perforation and summarizing the principle of hydrajet fracturing.According to Bernoulli's principle,jet supercharge superimposed upon annulus pressure surpass fracturing pressure,which will generate fractures and maintain fracture extension.Multiple technologies are also introduced including the assistant hydrajet fracturing technology,the annulus hydrajet fracturing technology,and the hydrajet acid-fracturing technology.The hydrajet fracturing tool is critical to realize field application and combination of coiled tubing technology with hydrajet fracturing technology.Hydrajet fracturing technology has been successfully abroad and good results have been obtained.However,it is still in the preliminary stage of field test in China.This paper presents some problems of the technology and discusses the prospect for its further development.