The shale oil development in Sinopec Jiangsu Oilfield is facing the problems of high investment and low production. After 45 years of development

there are a lot of abandoned old wells. Developing shale oil by old borehole side drilling can reduce drilling costs. In 2022

the sidetracking slimhole horizontal drilling in old wells is carried out in Huangzhuang. The slimhole drilling tools have the problems of large flexibility

difficult track control

slow drilling speed

small clearance

large air pressure consumption

poor cementing quality and high well control risk. In order to solve these problems

a system of efficient sidetracking slimhole horizontal drilling technology system is formed by the applications of large casing windowing

well track optimizations

high-efficiency drill bit+screw+LWD geosteering drilling

foam cementing

oil-based drilling fluid plugging

narrow gap well controlling

small hole coring

etc. A test application in H2CHF well shows that the actual drilling speed is up to 5.0 m/h

which is equivalent to the conventional drilling speed in adjacent wells

and the total drilling cost is reduced by 50 %

saved by 15 million. The new development and test would provide important ideas and reference for future development of shale oil in Jiangsu Oilfield.