5Hydraulics effect in Oil Well Drilling.pptx

PPT on Hydraulics effect in Oil Well Drilling

1. HYDRAULICS

2. Hydraulics In mud engineering, hydraulics is defined as the branch of science which deals with drilling fluids in a static condition or in a dynamic condition. Dynamic condition include: Circulation of the drilling fluid inside the casing or drill string and annulus Moving the casing or drill string up and down without circulation of drilling fluid Or combination of both

3. HYDRAULICS The ability of the drilling fluid to effectively transport cuttings from the bottom of the hole depends upon the hydraulics of the system and the properties of the drilling fluid. The good hydraulic system provide adequate impingement to hydraulic power at the formation Insufficient hydraulic power will lead to regrinding the cuttings in the bottom instead of transporting them to surface. This hole cleaning deficiency can cause accumulation of cuttings in the bottom of the hole and consequently impede the rate of penetration.

4. FUNCTIONS OF DRILLING FLUID The primary function of drilling fluid are to carry the drill cuttings to the surface to maintain the hydrostatic head to lubricate the drill string and bit to cool the bit while drilling to stop the loose formation from the caving-in

5. Annular Velocity Annular velocity: velocity of mud moving up in annulus Slip velocity is velocity of cutting particles falling down to the bottom Normally, annular velocity should be at least twice the slip velocity for proper hole cleaning

6. Annular Velocity Annular velocity of mud Slip velocity of particle

7. Annular Velocity Min value for proper bottom hole cleaning & avoiding poor ROP Max value to avoid hole erosion 17.50” hole : 18-30 meter/minute 12.25” hole : 21-33 meter/minute 8.50” hole : 36-54 meter/minute

8. Pressure Losses Standpipe pressure gauge gives total pressure loss Total Pr Loss = Pr loss in bit + Circ. System Pr losses Circ. System pr. losses = Loss in surface equipment + Loss in DP inside + Loss in DC inside + Loss in DP annulus + Loss in DC annulus P PUMP

9. CIRCULATION SYSTEM

10. Pressure Losses

11. PRESSURE LOSS In shallow depths, circulating pressure loss is less as compared to bit pressure loss. In deeper depths circulating pressure loss increases significantly. Pressure loss is directly proportional to depth as string pressure loss increases with depth. So in deeper intervals, a compromise between minimum discharge and pressure loss has to be made. Pressure losses are directly proportional to mud weight. Thus in high- pressure wells, pressure losses increase

12. Surface Equipment Pressure Losses This includes pr losses in Standpipe lines Rotary hose Swivel Kelly Divided in four categories based on length and internal dia

13. Annular Pressure Losses May be neglected in large holes like 17.5” and 12.25” holes as values are very less In smaller holes like 6” and 4.75” may have higher values and may be considered

14. Circulation rate Depends on Hole size Drill string size Annular velocity

15. NOZZLES Nozzles are made of hard material like tungsten carbide to avoid erosion, as mud passing through nozzles possesses very high jet velocity. A bit may have 3 or more nozzles of same or different sizes. Nozzle size is normally given in hole numbers like 6,7,8,9,10,11,12,13,14,15,16,18,20,22,24etc.Size ‘20’ means nozzle diameter of 20/32”. A triangular nozzle gauge is inserted inside nozzle hole to measure its size. Normally wide variation in nozzle sizes in a bit is not preferred. For example, 13-13-14 nozzles (area 0.408 sq.in.) will be preferable to 12-12-16 (0.416 sq. in.)

16. Operational Pressure Limit This is max allowed pump operating pr. Pump may be rated 3000 or 5000 psi or 7500 psi (New pumps) Liner rating depends on liner size A -1700-PT pump 7.0” liner : 205 kg/sq. cm. 6.5” liner : 237 kg/sq. cm. Surface equipment like rotary hose and hammer unions and mud pump condition may dictate lower pr. rating.

17. Operational Pressure Limit Max Operational pr = Liner rating – safety margin Normally safety margin is 250 psi or 18 kg/ sq.cm. 7” liner with rating of 205 kg/sq.. cm. Operational Pr limit = 205 - 18 = 187 kg/sq.. cm.

18. Pump Discharge : Triplex Pump Pump output in liter per stroke = 0.0386 D 2 h or it may be approximated to 0.04 D 2 h Where, D = Liner size in inch h= Piston stroke length in inch Ex. Liner size 7” and stroke length 12” PO = 0.0386 * 7 * 7 * 12 = 22.7 l/strk

19. The advanced Quadra pump goes beyond the limitations of triplex pumps, delivering reliable high-flow, high-pressure pumping performance that meets the needs of today and future drilling operations. New “ Quatro X ” gives 1597 GPM (flow rate) - Maxm . Pressure -7500 PSI Quadraplex Mud Pump

20. Proper Hydraulic Program What is needed ? Use of correct nozzle sizes Use of correct circulation rate What are the advantages ? Better bottom hole cleaning As a result of above, increase in ROP

21. Methodology of Hydraulic Program Utilize maximum available pump hydraulic horse power at bit 50 % to 65 % pressure loss in bit ( of standpipe pressure gauge ) Bit HHP/ sq. in. of hole size = 2 to 5 Jet velocity = 100 to 168 m/min = 1.67 to 2.80 m/sec

22. HYDAULICS OPTIMIZATION For optimizing hydraulics pump pressure should be as high as possible but subject to the maximum operating pressure. Pressure in the bit out side this range of 50-65% is recommended. Depending on the rig power, capacity ,status and pumps, higher bit pressure loss can be achieved in this range. There are two theories of optimization Maximum Bit Hydraulic Horse Power Theory Maximum Bit Impact Theory

23. HYDAULICS OPTIMIZATION Maximum Bit Hydraulic Horse Power Theory This theory gives about 65% of total pressure loss in the bit Nozzle size is smaller and pump pressure is high Higher jet velocity gives better ROP in top hole formation But later on higher jet velocity does not help in improving ROP in hard formations. At deeper depths, so much pressure losses not possible in bit nozzles as loss in drill string also increases significantly.

24. HYDAULICS OPTIMIZATION Maximum Bit Impact Theory At deeper depth, formation is hard and compact Excessive hydrostatic pressure of mud column does not allow cuttings to dislodge Impact force dislodges these cuttings. Pressure loss in bit is around 50 % in this theory. There is less wear ad tear of mud pumps. If one criterion does not lead to improvement in ROP , Then we can switch over to other criteria.

25. HYDAULIC HORSE POWER Hydraulic Horsepower HP = PQ/1714 Where, P = Pressure loss in psi Q = Circulation rate in gpm

26. Parameters for measuring effectiveness of hydraulics 1 . % of BIT HYDRAULIC HORSE POWER (BHHP) P bit %BHHP = x 100% P total BHHP per sq inch of hole size = {( P bit , kg/cm 2 ) X (Circulation rate , litre/sec)} 5.97 X (Hole dia, inch) 2 JET VELOCITY (Vn) , m/ sec = {1.55 * (Circulation rate , litre/sec)}/ Nozzle area, inch 2

27. 4. Bit Impact Force: Fbit ( lbf ) = ( ℓ /g)VQ Where, ℓ - density of fluid (lb/ft3), V- Jet velocity(ft/sec), Q- Circulation rate(ft 3/sec), g- Gravitational constant(32.7’/sec). 5. Bit Pressure loss: P = ℓ V 2 /2Cd2g Where Cd -Nozzle Coefficient(0.95)

28. Example of Hydraulics Optimization   Pump Oilwell : A-1700-PT Liner – 7” Stroke length – 12” Hole size = 12-1/4” Drilled depth – 2300 m 8” DC = 200 m 5” HWDP = 100 m 8” DC ID = 2-13/16” 5” HWDP ID = 3” 5” DP ID = 4.27” Pump efficiency = 97 % Optimization : Pump output (PO), liter/stroke = 0.0386 *(Liner size, inch) 2 * Stroke length (inch) 5” DP = 2300 - 200 - 100 = 2000 m

29. Hole size, inch Annular velocity, feet/ min Annular velocity, meter/ min 17-1/2 60-100 18-30 →12-1/4 70-110 →21-33 8-1/2 120-180 36-54 Annular velocity selected = 30 meter/ min (depends on pump and rig power) Annular Velocity Selection

30. Circulation Rate Selection Hole size 12-1/4” Drill pipe size 5” Annular velocity, feet/ min Annular velocity, meter/ min Circulation rate in liter/min 70 21 1363 80 24 1552 90 27 1741 100 →30 →1931 110 33 2120 Circulation rate selected = 1931 liter/ min but nearest round figure 1950 liter/minute as tables have circ. rate at a gap of 50 liters i.e. 1900, 1950, 2000 etc. Pump SPM Pump SPM = Circulation rate (liter/min) / PO (liter/stroke) = 1950 / 22 = 88.63 or 87

31. Selection of Surface equipment Type of equip- ment Standpipe Rotary hose Swivel Kelly Length, ft ID, inch Length, ft ID, inch Length, ft ID, inch Length, ft ID, inch 1 40 3 45 2 4 2 40 2-1/4 2 40 3-1/2 55 2-1/2 5 2-1/4 40 3-1/4 → 3 45 4 55 3 5 2-1/4 40 3-1/4 4 45 4 55 3 5 3 40 4 Equipment type: 3 as it gives less pr loss as compared to type 1 and 2. Most rigs Selected have 4” ID standpipe, 3” ID hose & 3-1/4” ID Kelly.

32. Pressure loss in kg/cm 2 in surface equipment Circ. rate liter/min Surface equipment type 1 2 →3 4 1800 12.74 4.69 2.68 2.01 1850 13.40 4.93 2.81 2.11 1900 14.08 5.19 2.95 2.22 →1950 14.79 5.44 →3.11 2.33 2000 15.50 5.71 3.26 2.44 2050 16.22 5.98 3.41 2.56 2100 16.97 6.25 3.57 2.67 2150 17.74 6.53 3.73 2.79 2200 22.54 6.81 3.90 2.92 Pr loss in surface equipment = 3.11 kg/cm 2

33. Pressure loss in kg/cm 2 /1000 m in 5” 19.5 ppf DP bore Circ rate, l/min Pr loss, kg/cm 2 Circ rate, l/min Pr loss, kg/cm 2 Circ rate, l/min Pr loss, kg/cm 2 1800 10.8 →1950 →12.5 2100 14.3 1850 11.4 2000 13.1 2150 15.0 1900 12.0 2050 13.7 2200 15.8 So pressure loss in 5” DP bore = 12.50 kg/cm 2 / 1000 m Total pr loss in 2000 m drill pipe bore = 2000 * 12.50 / 1000 = 25.00 kg/cm 2

34. Pressure loss in kg/cm 2 /100 m in 5” 50 ppf HWDP bore Circ rate, l/min Pr loss, kg/cm 2 Circ rate, l/min Pr loss, kg/cm 2 Circ rate, l/min Pr loss, kg/cm 2 1800 6.4 →1950 →7.5 2100 8.6 1850 6.8 2000 7.8 2150 9.0 1900 7.1 2050 8.2 2200 9.4 So, pr loss in 5” HWDP bore = 7.50 kg/cm 2 / 100 m Total pressure loss in 100 m HWDP bore = 100 * 7.50 / 100 = 7.50 kg/cm 2

35. Pressure loss in kg/cm 2 / 100 m in 8” DC bore Circ rate, l/min Pr loss, kg/cm 2 Circ rate, l/min Pr loss, kg/cm 2 Circ rate, l/min Pr loss, kg/cm 2 1800 8.8 →1950 →10.2 2100 11.7 1850 9.3 2000 10.7 2150 12.3 1900 9.8 2050 11.2 2200 12.8 So pr loss in 8” DC bore = 10.2 kg/cm 2 / 100 m Total pressure loss in 200 m drill collar bore = 200 * 10.20 / 100 = 20.40 kg/cm 2

36. Pressure loss in annulus Pressure loss in annulus can be neglected in 12-1/4” hole as pressure loss value is very small. But it will be significant in smaller size holes of 8-1/2”, 6” and 4-3/4”. May be neglected in 17-1/2” and 12-1/4” holes.

37. Pressure loss in circulating system Part of system where pr loss taking place Total loss in kg/cm 2 DC bore pressure loss 20.40 HWDP bore pressure loss 7.50 DP bore pressure loss 25.00 Surface equipment pressure loss 3.11 Annulus pressure loss Neglected Total Circulating Pressure Loss 56.01

38. Total pressure loss Total pr loss or Standpipe pr = Circulating system pr loss + Bit pr loss or Bit pr loss = Total pr loss or Standpipe pr minus Circulating system pressure loss Bit pressure loss = 50 – 65 % of standpipe pr or total pr loss for optimization

39. Table of Bit pressure loss (kg/cm 2 ) Liter/ min Nozzle size 13-13-13 13-13-14 13-14-14 14-14-14 14-14-15 14-15-15 15-15-15 1800 96.8 87.3 79.1 72.0 65.4 59.7 54.6 1850 102.3 92.2 83.6 76.1 69.1 63.0 57.7 1900 107.9 97.3 88.1 80.0 72.9 66.5 60.9 1950 →113.7 102.5 92.8 →84.5 76.8 70.0 →64.1 2000 119.6 107.8 97.7 88.9 80.7 73.7 67.4 2050 125.6 113.2 102.6 93.2 84.8 77.4 70.9 2100 131.8 118.8 107.7 98.0 89.0 81.2 74.3 2150 138.2 124.6 112.8 102.7 93.3 85.1 77.9

40. 13-13-13 Nozzles If 13-13-13 nozzles used, then bit nozzles pr loss = 113.7 kg/cm 2 Bit pr loss % = Bit pr loss/ ( Bit pr loss + Circ. system pr loss) = 113.7 / (113.7 + 56 ) = 113.7/169.7 = 67 % Nozzle size small. No provision for mud weight increase and change in discharge. Not recommended . Standpipe pr (170 kg) approaching liner pr limit. 14-14-14 Nozzles If 14-14-14 nozzles used, then bit nozzles pr loss = 84.5 kg/cm 2 Bit pr loss % = Bit pr loss/ ( Bit pr loss + Circ. system pr loss) = 84.5 / ( 84.5 + 56 ) = 84.5/140.1 = 60.1 % Within range and on higher side. OK . Standpipe pr (140 kg) below liner pr limit.

41. 15-15-15 Nozzles If 15-15-15 nozzles used, then bit nozzles pr loss = 64.1 kg/cm 2 Bit pr loss % = Bit pr loss/ (Bit pr loss + Circ. system pr loss) = 64.1 / (64.1 + 56) = 64.1/120.1 = 53.3 % Within range but on lower side. Acceptable but not so good. Standpipe pr (120 kg) much below liner pr limit and pump power not utilized fully.   16-16-16 Nozzles If 16-16-16 nozzles used, then bit nozzles pr loss = 50 kg/cm 2 (Not in table here) Bit pr loss % = Bit pr loss/ (Bit pr loss + Circ. system pr loss) = 50 / (50 + 56) = 50/106 = 47.2 % Not acceptable as below the range of 50 – 65 %. Standpipe pr (106 kg) much below liner pr limit and pump grossly under utilized.

42. Hole cleaning guidelines high angle wells Use recommended discharge for the hole size. Drilling rate may be controlled to avoid annulus loading. MW should be properly maintained as recommended to avoid hole instability. Use low-vis high-vis sweeps if hole cleaning problem persists. 42

43. MINIMUM PUMP DISCHARGE FOR HOLE CLEANING HOLE ANGLE HOLE SIZE / GPM 26” 17-1/2” 12-1/4” 8-1/2” MINIMUM DISCHARGE-GPM UPTO 35 DEG 700 500 400 300 35-55 DEG 1250 950 750 450 ABOVE 55 DEG - 1100 800 500 43

44. EFFECTIVE LENGTH FACTOR For different hole angles impirical factors can be used to multiply with section lengths to get effective section lengths & effective bottoms up strokes can be calculated. HOLE ANGLE IMPIRICAL LENGTH FACTOR FOR VARIOUS HOLE SIZES 17-1/2” 12-1/4” 8-1/2” 6” 0-10 1.5 1.3 1.3 1.3 10-30 1.7 1.4 1.4 1.4 30-60 2.5 1.8 1.6 1.5 60-90 3 2 1.7 1.6 44

45. Cutting Bed Impeller

46. PBL Sub (Ported Ball Locking) PBL sub is used for efficient circulation and it should be placed above BHA, MWD and LWD Tools. It can be used in loss circulation area.

47. Effect of rotation on lifting of cuttings STRING IN ROTATION STRING WITHOUT ROTATION ROTARY RPM 100 FLOW RATE CUTTING FLOW 47

48. 48 Recommendation Monitor the shakers continuously. Backream only as a last resort Wipe the drill string prior to making connections If prolonged periods of sliding is required, ream each stand prior to making connections. On trips out, pump out if increasing resistance is noted through horizontal / build sections. Wiper trip as hole conditions dictate.