Sidetracking horizontal wells can be used to control reserves

digging potentials and longitudinal residual oil and gas reservoirs. The researches at home and broad show that both restart production of long-time shutdown wells and increasing oil and gas production in low production wells need to imply sidetracking horizontal wells. The Sulige Gas Field

located in the Ordos Basin

is a giant gas field with reserves exceeded trillion

and in there an annual production capacity of 249×10

8

m

3

has been built.However

its single well yield is low

the rate of decline is fast

and th

e number of wells with daily production less than 3 000 m

3

accounts for 50 %. To explore side drilling horizontal wells and to improve gas recovery are the technical directions to achieve the steady production

cost reduction and efficiency increase in development of Sulige Gas Field. In view of the difficulties of sidetracking horizontal wells with small holes in the research block

the researches are carried out on safe drilling

completion technology and economic benefit. Twelve sidetracking horizontal wells are tested in site

with an average horizontal segment length of 672 m and an average drilling cycle of 49 d. The initial average daily gas production of a single well after sidetracking was 2.7×10

4

m

3

. The practice shows that it is technically feasible for the casing sidetracking horizontal well to improve gas recovery of low production and low efficiency wells in Sulige Gas Field.