The casing damage of horizontal "wells for shale gas

especially for deep shale gas

has always been a problem that troubles the staged fracturing development of shale gas.The conventional methods

such as casing patching and chemical plugging

cannot simultaneously meet the demands of high pressure

high flow rate and small bridge plug passing during fracturing

resulting in the difficult implementation of the staged fracturing technology through pumping of bridge plugs.Besides

the staged fracturing technology

with multi-packer is difficult to meet the requirements of pumping rate and scale due to the limited number of segments and limited displacement

resulting from the limited range of the ball-drop sliding sleeve.Taking Well-WY9-2 HF as an example

by conducting the researches such as risk demonstration

pipe string mechanical analysis and structural optimization

tool development and improvement

and wellbore simulation test

the following conclusions are drawn:the string with suspension packer is suitable for isolating the casing-damaged sections;the combination of the upper casing and the lower tubing for injection can raise the pump rate;the full bore infinite sliding sleeve can increase the number of segments and the pump rate;together with multi-packer

well control safety measures and high-rate segmented fracturing technique

the full bore infinite sliding sleeve is used to realize a large-scale and high-rate fracturing with 31 stages in Well-WY9-2HF

which achieves the expected targets and obtains a commissioning production of 8.75×10

4

m

3

/d.This technology can be used as a reference for the fracturing and commissioning of such wells.