Presentation on theme: "Chapter 5 Drilling Techniques and Drilling Problems."— Presentation transcript:
Chapter 5 Drilling Techniques and Drilling Problems
Part 1 Drilling Techniques
Well deviates < 3 deg. per 100 ft (30m) Cone with a maximum angle of 5 deg Straight hole
If the bit hits a subsurface rock layer with a dip greater than 45 deg., the bit tends to be deflected down dip. If rock layer dip less than 45 deg., the bit tends to be deflected updip. A well with an excessive angle in it that has not been drilled on purpose that way is call a crooked hole.
Modern rotary rigs can be controlled so that the well is drilled out at a pre-determined angle during directional or deviation drilling and ends up in a pre-determined location called target. Directional Drilling or Deviation Drilling
Directional Drilling (Patterns) Directionally drilled wells will usually be drilled according to one of three basic hole patterns.
Directional Drilling (Patterns) After making an initial deflection from vertical, the well may be drilled to the target, or deflected once more to allowed the bottom of the hole to be drilled vertically (“double dogleg”).
Directional Drilling The deviation begins when the hole is deflected using one of several techniques: (1) downhole hydraulic motors with a “bent sub” ( 井底馬達 與 彎曲接頭 ) (2) jet bits ( 沖鑽頭 ) (3) whipstocks ( 導斜具 )
Downhole hydraulic motors with a “bent sub”
Device used to kick off a well
A steerable downhole assembly ( 可控式井下總承 ) is a combination of stabilizers, bent subs, downhole turbine motor, and diamond bit that can maintain, drop, or build angle.
Plot of well survey data showing paths of directionally drilled wells