Application of Hydraulic Pulsed Jet Generator for ROP Enhancement in Shale Gas Well

Shale gas exploraiton has attracted much more attention than ever before due to the increasing energy demand in China. Low rate of penetration (ROP) and high drilling cost are two major challenges restricting the shale gas well drilling development. The hydraulic pulsed jet generator is a new ROP enhancement device, based on the advantages of pulsed jet. Because of impact pressure pulsation and local negative pressure effect, pressure distribution and stress state of the surface of the bottom-hole rock can make a change and then ROP is improved. This paper studied the mechnism of pulsed jet impacting on the shale, and compared the different effects of pusled jet and continuous jet. The hydraulic pulsed jet drilling technology has been tested in a shale gas well situated at Anhui of China. The test time was totally 245 hours. Its total net drill time was 211 hours in the third section. The internal structure of hydraulic pulsed jet generator was not damaged by erosion, and its working operation was in good condition. Compared with the adjacent intervals in the same well, it worked for 35 hours, and increased the ROP by approximately 27.7' and 105' individually. The results of the application in shale gas well shows that the hydraulic pulsed jet generator has a robust and simple structure, be cable of working for more than 200 hours and has increased the rate of penetration remarkably.