In the early days of land drilling most wells were drilled vertically, straight down into the reservoir. Although these wells were considered to be vertical, they rarely were. Some deviation in a wellbore will always occur, due to formation effects and
bending of the drillstring. The first directional drilling recorded instance of a well being deliberately drilled along a deviated course was in California in 1930. This well was drilled to exploit a reservoir which was beyond the shoreline underneath the Pacific Ocean.
It had been the practise to build jetties out into the ocean and build the drilling rig on the jetty. However, this became prohibitively expensive and the technique of drilling deviated wells was developed. Since then many new techniques and special tools have been introduced to control the path of the wellbore.
An operating company usually hires a directional drilling service company to: provide expertise in planning the well; supply special tools; and to provide onsite assistance when operating the tools. The operator may also hire a surveying
company to measure the inclination and direction of the well as drilling proceeds.
Directional Drilling Topic On Petroleum Support
In this chapter we will discuss: the applications of directional drilling ; the design of these wells; and the techniques used to drill a well with controlled deviation from the vertical. The next chapter will discuss the tools and techniques used to survey the position of the well (determine the three dimensional position of all points in the wellbore relative to the wellhead).