INTRODUCTIONTODRILLINGBIT钻头英文简介ppt课件

1、DRILL BIT SELECTION .One of the more confusing aspects of oilwell drilling to the young and old alike is the numerous types of drill bits. The largest manufacturer of drill bits makes 34 types and 33 sizes (diameters) and many more on request.IADC organization has a system of assigning a designation

2、 code to each bit type. .ROLLER CONE.Series TypeFeature Feature (2)ROLLER CONE.Example Code: 5 2 2 R5 = code for insert bits“2 = code for soft to medium formation“2 = code for roller bearing air cooled“R = code for reinforced welds.FIXED CUTTERS.Cutter type and body material, Cross-section profile,

3、Hydraulic design, and Cutter size and densityFIXED CUTTERS.First code designations areD - natural diamond/matrix bodyM -polycrystalline diamond cutters/matrix bodyS - polycrystalline diamond cutters/steel bodyT - thermally stable polycrystalline diamond cutters/matrix bodyO - otherSecond code design

4、ations arelong taper/deep conelong taper/medium conelong taper/shallow or no cone (parabolic)medium taper/deep conemedium taper/medium conemedium taper/shallow or no cone(rounded)short taper/deep cone (inverted)short taper/medium coneshort taper/shallow or no cone (flat).Third code designations areb

5、laded/changeable jetsbladed/fixed portsbladed/open throatribbed/changeable jetsribbed/fixed portsribbed/open throatopen face/changeable jetsopen face/fixed portsopen face/open throatalternative codesradial flowcross flowother .Fourth code designations arecutter size; large, medium, and smallcutter d

6、ensity; light, medium, heavy .Example Code: M 5 8 2M = code for polycrystalline diamond cutters/matrix body“5 = code for medium taper/medium cone“8 = code for fixed ports/open face“2= code for medium cutter size/light cutter density .Drill Bit Characteristics Teeth length and sizeNumber of teeth (in

7、dexing)Cone offsetCone bearing typeHeel row teeth configurationGauge configurationJournal shaft angle (how flat or round the bottom hole pattern)The teeth length and size and cone offset affect the ROPThe next three items on the list have a large affect on the bit life. Item 7 affects hole straightn

8、ess. Roller cone drill bit characteristics of importance in regard to selection are:.ROCK FAILURE MODELSTwo rock failure models are recognized: the tension and shear It has been argued that the shear type action is more efficient than the tension model.DRILL BIT SELECTION CRITERIA A popular equation

9、 for cost comparisons is the total cost per foot equation. If the bit were operated to its optimal life at its optimum weight and speed, then the cost would be the lowest cost per foot for the bit. .Is the bit life if the bit is terminated by Bearing failure, Total tooth wear, or The reduction of it

10、s drilling rate to an uneconomical one. p.s. Formation changes often mask the latter optimal life and care must be exercised. OPTIMAL LIFE.ExampleFollowing performance data is given:ITEMSTEEL TOOTHINSERT TOOTHBit Cost$277.88$1521.32Trip6:18 hrs/min6:32 hrs/minRotation Time10:01 hrs/min58:42 hrs/minD

11、own TimeNoneNoneBit Footage180 ft880.5 ftRig Cost Rate 375 $/hrSameFraction Tooth Wear1/2Not ApplicableFraction Bearing Wear 6/88/8Average Drilling Rate18 ft/hr12.5 ft/hrBit Size7-7/8 in.7-7/8 in.Bit Weight30,000 lbs40,000 lbsRotary Speed85 rpm60 rpm .The plot shows that had the steel tooth bit been

12、 pulled at its optimal life (6 hours and 34 minutes) it would have had a lower cost per foot: $34.05/ft versus $35.47/ft. .Trip times may be taken from the IADC tour sheet or may be taken from the Geolograph unit or some other device. A chart versus depth must be constructed for each rig for ultimat

13、e analyses. TRIP TIME.ExampleA bit is run at a depth of 8,000 feet and pulled at a depth of 8,500 feet. How many hours is the trip time for this bit?Trip T=(5.2+5.7)/2=5.45 hrFrom the chart a round trips at 8,000 feet and 8,500 feet require 5.2 hours and 5.7 hours, respectively.OPTIMAL WOB & RPMThe

14、purpose of selecting bit weight and rotary speeds are duce the lowest drilling cost per foot2.control the direction of the drill hole3.find overpressured zones4.satisfy equipment limitations (solids removal, BHA, etc.)5.develop a satisfactory cuttings description log .CONTOUR METHOD The metho

15、d consists of constructing the previous figure in a two dimensional presentation. .ExampleSix insert bits have been run and their performance and total cost per foot data are listed in the table. BIT #ROT. TIME FOOTAGE TCFHr:Min $/FT 1 58:4273435.28 2 39:0536051.51 3 101:2185548.99 4 62:0761444.24 5

16、 47:1651741.27 6 56:3365838.14 .The optimal WOB and RPM are 40,000 lb and 50 rpm ($35.00/ft).ANALYTICAL METHODThe same procedure could be used for determining optimal WOB, and RPM for the steel tooth, roller bearing bit; however, an Galle and Woods analytical method is available for these bits. DEFI

17、NITION OF TERMSBS= Bit diameter; inchW= Actual weight on bit; 1000 poundsW= Equivalent weight on a 7-7/8 inch bit; 1000 poundsTT= Trip time; hrsR= Cost rate of the drilling operation; $/hrsT= Time; hrsG= Bit Cost + Trip Cost; $TC= Trip cost; R * TT; $D= Fraction of tooth height worn away; 8thsB= Fra

18、ction of bearing life consumed; 8ths DT= Down time; hrsRT= Rotation time; hrsF=Bit footage; ft .Galle and Woods published the following relationships for the rate of tooth wear. TOOTH WEARA=Correlation coefficient for tooth wear and is called the formation abrasiveness factor .Integration of the too

19、th wear equation gives bit rotation timeTooth wear Equation.Rotary Speed, N=80.BEARING WEAR S=correlation coefficient called the drilling fluid factor Others published the following relationship for the rate of bearing wear.Rotary Speed, N=80.RATE OF PENETRATION C=correlation coefficient called the

20、formation drillability factor The values of and are determined from drill-off test and range between.6 1.0.4 1.0p=1.0 if flat tooth wear (non-sharpening)p=0.5 if self sharpening .Bit footage (F) is equal to Rate of Penetration x Rotation Time Equation of ROPSo far, RT is determined either by setting

21、D=1 (complete bit tooth wear) orB=1 (complete bearing wear) Whichever comes first. D RT F D RT F D RT F D RT F D RT F D RT F D RT FRotary Speed, N=80.The total cost per foot equation is. D RT F TCF D RT F TCF D RT F TCF D RT F TCF D RT F TCF D RT F TCFRotary Speed, N=80.The parameters A, C & S are usually computed with data gathered from other similar drill bits which were run in similar formations, at similar depths, with similar bottom hole assemblies, with similar hydraulics, with similar