At present

the water cut of fault block 14-1 reservoir in Banqiao Oilfield is 98.1 % and the recovery degree is 10.93 %. Conventional water control and oil stabilization technology can not solve the problems of high water cut

low productivity and poor economic benefit. Compared with conventional water control and oil enrichment technology

CO

2

huff and puff cone has the advantages

of simple technology

short construction period and high success rate. The mechanism of precipitation and oil increase by CO

2

huff and puff is studied by numerical simulation technology. On this basis

the technological parameters of CO

2

huff and puff are optimized

and the optimal technological scheme of CO

2

huff and puff for horizontal wells in reservoirs is determined. On the basis of scheme optimization

CO

2

huff and puff scheme was implemented on site. The results show that CO

2

huff and puff achieves water control and oil increase in horizontal wells at extra high water cut period by extracting the intermediate components of crude oil through gas drive pressure cone and reducing the viscosity mechanism of crude oil. By comparing the cumulative oil increase and oil exchange rate of single well under different process parameters

the optimal injection rate of CO

2

is 600 t

injection rate is 4.0 t/h

soaking time is 17 d

fluid production is 16 m

3

/d

and the number of huff and puff cycles is two. Field pilot test of well 45H shows that the fluid production of well 45H is 12 m

3

/d

the water cut is reduced from 98.1 % to 62.5 %

and the oil production is increased from 1.6 m

3

/d to 4.73 m

3

/d. CO

2

huff and puff can control bottom water coning

reduce water cut and restore productivity effectively. The results show that horizontal well CO

2

huff and puff has good adaptability and application prospect for similar reservoirs in Banqiao Oilfield.