4Fig. 8.39: Bent sub unconstrained and constrained in a wellbore. NonmagneticDrill CollarOrienting SubHoleBent SubMud MotorBent Sub AngleBitFig. 8.39: Bent sub unconstrained and constrained in a wellbore.b is not necessarily equal to the bent sub angle, but it may be close in (a) above
5Problem 1Determine the effective bent sub response for a 1 1/2o bent sub in a motor run where at 6,357’, a = 1o and e is S85E and at 6,382, aN = 1o and eN is S20E; the tool face is 160o right of high side.
6Solution to Problem 1Calculate b from Eq. 8.53:Dogleg severity:
7Solution to Problem 1 - cont’d If the mud motor length is 25 ft from the bit face to the bent sub, the maximum angle change that could be reached if there are no restrictions is:The lower rate of build implies that the formation resisted the maximum rate of build by a factor of:An efficiency factor?
8b = Bent Sub Angle?Since the value of b for any given run may differ from the bent sub angle, it should not surprise us ifDe predicted = De measuredLet us look at some examples.
9Fig. 8.40: Example of three jetting stops while trying to kick off and set the wellbore lead.
10Jetted 7’ 1745-52’ Surv 1722’: S32W 2.25o g = -122o Orient S90E Nozzle Orientationg = -122oOrient S90EFinal 1799’:S30E o
13Directional Drilling Measurements The trajectory of a wellbore is determined by the measurement of:inclination q, a, Idirection f, e, Ameasured depth DMD, DL, L
14Directional Drilling Measurements - cont’d A tool-face measurement is required to orient:a whipstockthe large nozzle on a jetting bita bent sub or bent housing
15Directional Drilling Measurements - cont’d Tools availablesingle-shot magnetic or gyroscopicmulti-shot magnetic or gyroscopicmagnetometers, accelerometers, MWD tools
16Magnetic Single-Shot Instrument Recordsinclinationdirectiontool face positionon sensitized paper or photographic filmInclination may be determined bya float on a liquida pendulum
17Magnetic Single-Shot Instrument Unit may be triggered by:clock timer.inertial timer (after stop).Unit may be dropped (pumped down) and later retrieved by wireline or the drillpipe.
18Magnetic Single-Shot Instrument Single-shot instruments are used:to monitor progress of directional-control well.to monitor progress of deviation-control well.to help orient tool face for trajectory change.
19Magnetic Single-Shot Instrument - cont’d Procedure:load film into instrumentactivate timer (activate stopwatch)make up the tooldrop the toolretrieve tool (wireline or drillpipe)
20LightHousingCenter PostFloatFluidReference MarkMain FramePhotographic DiscA. 0-20oAngle-Compass UnitB. 0-70oAngle-Compass UnitFig. 8.41: Schematic diagrams of magnetic single-shot angle-compass unit (courtesy Kuster Co.).
211. Pendulum2. Circular Glass3. Compass4. Pressure equalization5. Cover glassFig. 8.43: Pendulum suspended inclinometer and compass unit for a 0 to 17oo singe-shot unit.Indicated inclination 5o. Direction of inclination N 45 degrees 0’ or azimuth 45 degrees.
22Fig. 8.42: Single-shot film disks (courtesy of Kuster Co.). A/C UnitsPlumb-Bob UnitsIncl. Only UnitsFig. 8.42: Single-shot film disks (courtesy of Kuster Co.).InclinationDirectionTool Face Angle
23Fig. 8.12: Pendulum assembly: a) plumb- bob angle unit b) drift arc inclinometer Glass ringPiston(a)(b)
24Hole direction with reference to Magnetic North Fig. 8.13: Schematic drawing of magnetic single and multi-shot instruments.N35oW I = 5.5o
25Fig. 8.44: Cardan suspended compass and inclinometer for a single-shot Inclination ScaleFig. 8.44: Cardan suspended compass and inclinometer for a single-shot5o to 90o unit.
26Fig. 8.45: Typical magnetic single-shot tool with landing sub. Wire Line SocketRope SocketOvershotSwivelStabilizerStabilizer FingersFig. 8.45: Typical magnetic single-shot tool with landing sub.Protective CaseOrienting Anchor & PlugMule Shoe MandrelBottom Hole Orienting SubBottom Landing AssemblyTakes time. Rig time is costly. Temperature limitation. May have to pump down.
27Fig. 8.46: Typical single-shot operation. Free Falling to BottomReady to be DroppedTool seatedRetrieve single shotFig. 8.46: Typical single-shot operation.
28Fig. 8.46: Typical single-shot operation. Timer On3 min.Compass UnitSingle Shot Ready to be Dropped*Single Shot Instruments are run on slickline if there is a mule shoe sub in the holeSingle Shot Free Falling in Mud to BottomFig. 8.46: Typical single-shot operation.Non Magnetic Drill CollarOrienting Sub Sleeve
29Fig. 8.46: Typical single-shot operation. 3 min.Fig. 8.46: Typical single-shot operation.Wireline unit to retrieve single shot10 min.Overshot Used to Fish Single ShotTool seated in orienting sleeve or at stop taking picture
30Fig. 8.47: Arrangement of the mule shoe for orienting a mud motor. Fishing NeckTop ViewNon Magnetic CollarDirection of Tool Face Via Bent SubSingle ShotMule Shoe Orienting SubOrienting Sleeve Lined up with Bent SubBent SubMule Shoe Key PositionMud MotorFig. 8.47: Arrangement of the mule shoe for orienting a mud motor.Existing CenterlineNew Centerline
31Magnetic Multishot Instruments Are capable of taking numerous survey records in one run.May be dropped down the drillpipe or run on wireline in open hole.The unit contains a watch that is spring wound and uses the power of the spring to operate a timer cam.
32Fig. 8.48: Typical arrangement for landing a multi-shot instrument. Non-Magnetic Drill Collar(s)Compass PositionFig. 8.48: Typical arrangement for landing a multi-shot instrument.Multi-shot InstrumentLanding Plate
34Light Switch LeverGeneva GearWatch SectionMotorKnife Switch TerminalGeneva Drive Wheel AssemblyWinding StemMotor Lever SwitchWatch SwitchFilm SprocketSupply Film SpoolTakeup Film SpoolTime Cycle CamFig. 8.50: Views of the watch and camera unit of a typical multi-shot tool.
35Magnetic Multishot - cont’d The multishot tool is usually dropped down the drillpipe and landed in the nonmagnetic drill collar.During the trip out, a survey is taken every 90 ft, i.e. every stand.
36Magnetic Multishot - cont’d More closely spaced stations could be obtained by stopping the pipe more often, and waiting for a picture.A stopwatch at the surface is synchronized with the instrument watch.
37Fig. 8.51: Use of the surface watch while running a magnetic multi-shot operation. Synchronize with instrument watch by starting at the instant camera lights go on.
38Time Intervals: A. 10 seconds - Lights are on, exposing film B. 15 seconds - Delay before moving This is an allowance for instrument watch lag during survey.
39Time Intervals - cont’d C. 20 seconds - Instrument is idle allowing movement of drill string without affecting picture. Most moves require sufficient time for taking one or more shots while movingD. 15 seconds - Minimum time for plumb bob and compass to settle for good picture, plus allowance for instrument gain during survey.
40Fig. 8.52b: Projection of one survey frame for determining inclination and direction.
41Steering Tools Used with mud motors and bent sub Standard Measuring CableUsed with mud motors and bent subCan either pull every stand or use a side entry sub for continuous drillingMonel DCProbeMule ShoeBent SubMud Motor