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Chapter 5 Drilling Techniques and Drilling Problems

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1 Chapter 5 Drilling Techniques and Drilling Problems

2 Part 1 Drilling Techniques

3 Straight hole Well deviates < 3 deg. per 100 ft (30m)
Cone with a maximum angle of 5 deg

4 A well with an excessive angle in it that has not been drilled on purpose that way is call a crooked 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.

5 Directional Drilling or Deviation Drilling
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.

6 Directional Drilling (Patterns)
Directionally drilled wells will usually be drilled according to one of three basic hole patterns.

7 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”).

8 起斜點 (Kick off point, KOP)

9 Uses of Directional Drilling

10 Situation Requiring Directional Drilling
側井 改正井


12 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)

13 Downhole hydraulic motors with a “bent sub”


15 Device used to kick off a well

16 Jet bit

17 Jet bit

18 Whipstock

19 Whipstock

20 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.

21 Plot of well survey data showing paths of directionally drilled wells

22 Depth of a Well

23 Extended Reach Well and Horizontal Drain Well


25 Part 2 Drilling Problems

26 Problems while drilling
Fishing 打撈 Stuck pipe 卡鑽 Sloughing shale 頁岩崩落 Lost circulation 喪失循環 Formation damage 地層損傷 Corrosive gases 腐蝕性氣體 Abnormal high pressure 異常高壓

27 Comment situations requiring fishing jobs
Differential sticking 差壓黏卡 Key seating 匙孔卡鑽 Sloughing shale 頁岩崩落(泥坑) Poor mud properties 鑽屑停滯或糊鑽 Fatigue failures 金屬疲勞破壞 Foreign objects 外來的掉落物件

28 Differential sticking of drillpipe because of heavy mud weight

29 Crooked wellbore showing view of “key seated” drillpipe


31 Equipment used for a fishing job
For stuck drillpipe (卡鑽) Overshot 打撈碗 Spear 打撈矛 For foreign objects (掉落物) Junk baskets 打撈籃

32 Two types of catching tools

33 Three types of junk baskets for retrieving foreign objects from hole

34 End of this chapter

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