Study on New Technologies of Ultra-short Radius Radial Horizontal Wells and Application in Coal-bed Methane Development

On the basis of analysis on the characteristics of CBM reservoirs, this paper further analyzes the damage mechanism on CBM reservoirs caused by drilling pressure and drilling fluid during the drilling process, and finally works out a conclusion on reservoir protection in aspects of drilling technology and drilling fluid. Abstract:Ultra-short radius radial horizontal wells technology is a new stimulation for oil development in recent years. It has got a good stimulation effect in old oil or gas wells, bad fractured wells, and near borehole damage wells. However, this technology has not been used widely due to some critical technologies' problems such as turning system, hydraulic rock-breaking bit, etc. In this paper, both pros and cons of the critical technologies of common radial horizontal wells technology are analyzed. Meanwhile, new progresses and advantages in CBM drilling of these critical technologies both home and abroad are also introduced in detail. Abstract: In order to reduce the cost in drilling, China United Coalbed Methane Corporation adopts slim hole drilling technology to drill parameter wells. In this paper, key parts of this technology are introduced, which includes selections of surface equipment, drill string, drilling parameter and drilling fluid, maintenance of drilling fluid, control measures of solid content, deviation prevention, coring technology, and logging technology. These techniques are successfully applied in the Qingshan project in Baotian, Guizhuo Province, which only cost less than half of what may cost in conventional oil and gas well drilling. According to the above discussion, a conclusion can be reached that slim hole drilling is feasible for the drilling of parameter well.