PETE 411 Well Drilling

1. PETE 411Well Drilling Lesson 24 Kicks and Well Control

2. Kicks and Well Control Methods The Anatomy of a KICK Kicks - Definition Kick Detection Kick Control (a) Dynamic Kick Control (b) Other Kick Control Methods * Driller’s Method * Engineer’s Method

3. Read:Applied Drilling Engineering, Ch.4 HW #13dc - Exponentdue Nov. 6, 2002

8. Causes of Kicks

9. Causes of Kicks

10. Causes of Kicks

17. What? What is a kick? An unscheduled entry of formation fluid(s) into the wellbore

18. Why? Why does a kick occur? The pressure inside the wellbore is lower than the formation pore pressure (in a permeable formation). pw < pf

19. How? Howcan this occur? Mud density is too low Fluid level is too low - trips or lost circ. Swabbing on trips Circulation stopped - ECD too low

20. What ? Whathappens if a kick is not controlled? BLOWOUT !!!

21. Typical Kick Sequence 1. Kick indication 2. Kick detection - (confirmation) 3. Kick containment - (stop kick influx) 4. Removal of kick from wellbore 5. Replace old mud with kill mud (heavier)

22. Kick Detection and Control Kick Detection Kick Control

23. 1. Circulate Kick out of hole Keep the BHP constant throughout

24. 2. Circulate Old Mud out of hole Keep the BHP constant throughout

25. Kick Detection Some of the preliminary events that may be associated with a well-control problem, not necessarily in the order of occurrence, are: 1.Pit gain; 2.Increase in flow of mud from the well 3. Drilling break (sudden increase in drilling rate)

26. Kick Detection 4. Decrease in circulating pressure; 5. Shows of gas, oil, or salt water 6. Well flows after mud pump has been shut down 7. Increase in hook load 8. Incorrect fill-up on trips

27. Dynamic Kick Control[Kill well “on the fly”] For use in controlling shallow gas kicks No competent casing seat No surface casing - only conductor Use diverter (not BOP’s) Do not shut well in!

28. Dynamic Kick Control 1. Keep pumping. Increase rate! (higher ECD) 2. Increase mud density 0.3 #/gal per circulation 3. Check for flow after each complete circulation 4. If still flowing, repeat 2-4.

29. Dynamic Kick Control Other ways that shallow gas kicks may be stopped: 1. The well may breach with the wellbore essentially collapsing. 2. The reservoir may deplete to the point where flow stops.

30. Conventional Kick Control{Surface Casing and BOP Stack are in place} Shut in well for pressure readings. (a) Remove kick fluid from wellbore; (b) Replace old mud with kill weight mud Use choke to keep BHP constant.

31. Conventional Kick Control 1. DRILLER’S METHOD **TWO complete circulations ** Circulate kick out of hole using old mud Circulate old mud out of hole using kill weight mud

32. Conventional Kick Control 2. WAIT AND WEIGHT METHOD (Engineer’s Method) ** ONE complete circulation ** Circulate kick out of hole using kill weight mud

33. Driller’s Method - Constant Geometry Information required: Well Data: Depth = 10,000 ft. Hole size = 12.415 in. (constant) Drill Pipe = 4 1/2” O.D., 16.60 #/ft Surface Csg.: 4,000 ft. of 13 3/8” O.D. 68 #/ft (12.415 in I.D.)

34. Driller’s Method - Constant Geometry Additional Information required: Kick Data: Original mud weight = 10.0 #/gal Shut-in annulus press. = 600 psi Shut-in drill pipe press. = 500 psi Kick size = 30 bbl (pit gain)

35. Constant Annular Geometry. Initial conditions: Kick has just entered the wellbore Pressures have stabilized

36. Successful Well Control 1. At no time during the process of removing the kick fluid from the wellbore will the pressure exceed the pressure capability of the formation the casing the wellhead equipment

37. Successful Well Control 2. When the process is complete the wellbore is completely filled with a fluid of sufficient density (kill mud) to control the formation pressure. Under these conditions the well will not flow when the BOP’s are opened. 3. Keep the BHP constant throughout.

38. Calculations From the initial shut-in data we can calculate: Bottom hole pressure Casing seat pressure Height of kick Density of kick fluid

39. Calculate New Bottom Hole Pressure PB = SIDPP + Hydrostatic Pressure in DP = 500 + 0.052 * 10.0 * 10,000 = 500 + 5,200 PB =5,700 psig

40. Calculate Pressure at Casing Seat P4,000 = P0 + DPHYDR. ANN. 0-4,000 = SICP + 0.052 * 10 * 4,000 = 600 + 2,080 P4,000 = 2,680 psig

41. Calculate EMW at Casing Seat This corresponds to a pressure gradient of Equivalent Mud Weight (EMW) = ( rmud = 10.0 lb/gal )

42. Calculate Initial Height of Kick Annular capacity per ft of hole:

43. Calculate Height of Kick hB

44. Calculate Density of Kick Fluid The bottom hole pressure is the pressure at the surface plus the total hydrostatic pressure between the surface and the bottom: AnnulusDrill String PB = SICP + DPMA + DPKB PB = SIDPP + DPMD

45. Density of Kick Fluid (must be primarily gas!)

46. Circulate Kick Out of Hole NOTE: The bottom hole pressure is kept constant while the kick fluid is circulated out of the hole! In this case BHP = 5,700 psig

47. Constant Annular Geometry Driller’s Method. Conditions When Top of Kick Fluid Reaches the Surface BHP = const.

49. Top of Kick at Surface As the kick fluid moves up the annulus, it expands. If the expansion follows the gas law, then

50. Top of Kick at Surface Ignoring changes due to compressibility factor (Z) and temperature, we get: Since cross-sectional area = constant