Abstract
The drilling cost represents a significant portion of total well cost, especially for directional wells. The major component of drilling cost is determined by how fast a well is drilled, i.e., rate of penetration (ROP). Many factors affect ROP including bit type and condition, formation characteristics, and drilling parameters. One factor that is usually ignored is the direction of drilling (well azimuth). Literature introduces many thoughts about effect of well azimuth on important issues like wellbore stability, but unfortunately it lacks high quality researches about azimuth/performance relationship. The objective of this paper is to test the influence of drilling azimuth on drilling performance.
This relationship was studied in terms of ROP, and drillability exponent (DEXP), which can be used for drilling performance assessment besides well control applications. Drilling data from different areas was processed and categorized by fields and formations. In-Depth statistical analysis was performed, and visualization tools like heat maps were generated to assess the relationship between drilling performance and drilling azimuth. The noise effect of various factors like bit type and condition was normalized so that the resultant output was expressive of azimuth effect.
The resultant heat maps act in the same manner as mechanical earth models (MEM) were used for wellbore stability studies. This occurs by suggesting the most appropriate azimuth to drill the well more efficiently in terms of time and power consumption. Python libraries were implemented for the sake of fast data processing with visually comprehensible output reports that were used for the planning of future drilling campaigns. These reports have ROP and DEXP graphed against well azimuth and inclination to magnify the effect of both horizontal earth stresses and attack angle of the bit. Although the output is conclusive in most cases, this is not the fact in all wells and further investigations are required.
The result of this research is very beneficial tool that can be used while planning directional trajectory of oil and gas wells to speed up the drilling operations and cutting the cost back. By allocating suitable targets to certain surface locations, the required horsepower to drill the well at the same ROP is reduced and the rig time at the same power is significantly cut.