Von Mises Stress
2 V2 Sa - Sr 2 St - Sr 2 Sa - St 2 6 Tt2 Tr2 Tz2 V von Mises stress or general stress psi Sa axial stress in the wall of the drillpipe psi Sr radial stress in the wall of the drillpipe psi Sj. tangential stress in the wall of Tt tangential shear stress normal to the longitudinal axis of the drillpipe psi Tr radial shear stress normal to the longitudinal axis of the drillpipe psi Tz axial shear stress parallel to the radial axis of the drillpipe psi The formula for computing the external...
Plug Flow Cementation
The plug flow technique is very efficient but it is limited to cementations of small volumes and where the mud in the hole is of low density. The technique calls for Reynolds numbers of 100 or less, no cement slurry retarders or thinners, and for the cement to be in contact with the mud no spacer . It can be demonstrated in laboratory experiments that a thickened plug or ball of flocculated cement and mud is formed in the annulus which when aided by buoyancy pushes the mud from the hole.
Hopkin S Particle Slip Velocity Chart
An example problem follows Hopkins slip velocity chart. Hopkin ran over 2,000 dynamic particle lifting tests with a 8 foot long 4.5 diameter vertical tube with 13 types of mud and 52 particle shapes and sizes. The particles were circulated from the bottom of the tube to the top with the fluid in laminar, transitional, and turbulent flow. Mud Marsh funnel viscosities ranged from 26 to 1,000 seconds qt. A minimum of three data points were collected for each test. A curve fit of his graph not...
Casing Centralizer Spacing
The purpose of centralizers on casing is to provide separation for the casing from the wall of the hole. This separation is called standoff. The strength of a centralizer is the amount of force required to compress its bows a given distance. Thus, stronger bows provide more standoff for casing. Wall force is the sum of two components 1 the product of the tension in the pipe and the dogleg severity of the hole and 2 buoyed weight of the pipe. The moments transmitted through the string of pipe in...
Other Common Fishing Tools
There are a wide variety of fishing tools and equipment. The following is a short description of common tools. BAILER A pipe with a compression actuatedvalve which is used to place cement in a hole or clean cavings out of the hole. BUMPER SUB A drill string sub withsmandrel and housing which may be extended with tension or closed with compression. Used in combination with jars.
Whirling Motion Of The Drill String
The rule of not permitting turbulent flow in the open hole annulus may be revoked by considerations surrounding an orbiting drill string. The figure is a view of a cross section of a drill string while looking into the hole. The mud will be displaced by the orbiting drill string in the direction of the arrow captioned with MUD FLOW. The direction of the flow of the mud is horizontal. However, while this motion is coupled with vertical annular flow, mud will flow in a spiral motion. With no slip...
Plug Cementation Variables
The cement bond log which was taken from a plug flow cementation indicates an excellent cement pipe bond. Other points are that the cement to mud transition is sharp, free pipe is clearly shown, and bonded pipe to free pipe signal strength is excellent. The following analysis points out that the cement was in plug flow. Data is taken from the well log and the power law sheet. The cement properties are those for the class G cement. Cedent Bond Leg Cement 200sx, class G, 15.9 g, Bonding increases...
Weight On Drill Bit In Vertical And Inclined Holes
The BHA is not designed for the purpose of putting weight on the drill bit. The prevalent purpose for a BHA is to eliminate axial and torsional buckling of the drillpipe. This purpose is not achieved in some cases if the buoyed weight of the BHA is only slightly larger than the weight on bit. One exception to the above statement is the situation in which moderately hard rock is being drilled at a very shallow depth. In this case the weight of the drillpipe would be insufficient to achieve an...
Cement Plugs For Sidetracking
The strongest cement plug is a plug composed entirely of neat cement. However, setting a plug in deep hot wells may require silica flour to prevent retrograde of its strength. The problem in setting good cement plugs is the swapping out of the cement and the mud. Swapping out is a process in which lighter mud below the un-set heavier cement buoys a passage way up and through the cement. Swapping out is routinely prevented by setting a viscous bentonite pill in the hole below the bottom of the...
Cement Sheath Within Casing Settling Inside Pipe
Sabins found cement sheaths of 5 16 in thickness within the casing in horizontal wells and that cement plugs bypassed the cement solids build-up. The sheath was primarily composed of cement solids which were thought to have settled out of the cement slurry and formed a bed or sheath on low side of the casing. He found that cements with viscometer readings greater than 11 at both the 3 rpm and 6 rpm values and yield points greater than 13 lb lOOsq.ft. at room temperatures eliminated the cement...
Surge And Swab For Long Pipe Strings
Pressure surges within the borehole may be caused by one or more of the listed operations 1. Friction between the mud and the pipe because of pipe movement. 2. Inertial force because of accelerating or decelerating the mud in the hole when initiating or terminating pipe movement or circulation. 3. Breaking of the thixotropic gel of some muds when initiating or terminating pipe movement or circulation. 4. Balling of the bit or a stabilizer when pulling the drillstring. A S S 'm S gt S m V i S A...
REFERENCES Ymq
1. Lubinski, A., Maximum Permissible Dog-Legs in Rotary Bore Holes, AIME Transactions, 1961, Vol. 222 2. Lubinski, A., A Study of Buckling of Rotary Drilling Strings, API DRILLING AND PRODUCTION PRACTICES. 1950 3. Lubinski, A., Influence of Tension and Compression on Straightness and Buckling, API, 1951, Vol. 31 4. Woods, H.B. and Lubinski, A., Use of Stabilizers in Drill-Collar String, OIL AND GAS JOURNAL. April 4, 1955 5. Woods, H.B. and Lubinski, A., Charts Solve Hole-Deviation Problems, OIL...
Circle Of Uncertainty
The circle of uncertainty can be generated by first recalculating a directional survey with tolerances of inclination and azimuth added to the values of inclination and azimuth of the original survey. Then the approximation to the radius, R', of the circle of uncertainty is the distance between two similar stations computed with each of the surveys. The radius, R, is within an oblique plane which is perpendicular to the line of borehole just above the original station. A projection of a circle...
Centralizer Spacing Equation
F 2 T sin DLS -y WF b CS sin 0 exact transcendental function force on each centralizer if, spaced CS feet apart lbf centralizer spacing feet dogleg severity degrees 100 feet example DLS .03 weight per foot of pipe steel only lbf foot buoyancy factor no units average inclination angle near the centralizer degrees tension in the wall of the pipe for drill pipe see tension in drill pipe in directional wells lbf T .0408 TVD p.d2-peD2 cos 0 w S for casing only in the slant portion of the hole lbf WF...
Tapered Drillpipe Strings
A tapered string contains more than one OD, tooljoint, weight, grade, or levels of wear. The problem with tapered strings is ascertaining how much weight can be placed on the weight indicator without failing any one of the sections of the tapered string. COMBINED TENSION, TORSION, BENDING, amp PRESSURE LOADS Combined tension, torsion, bending, and pressure loads are frequently placed on drillpipe. The normal drilling operation of making hole does this. However, the damaging combined loads will...
Round Thread With Bending And Tension
API Bulletin 5C3, page 24, gives the following formula which was taken from the work of Clinedinst for the affect of bending and tension on the fracture strength of round thread pipe. Two bending cases exist. The joint strength of pipe is the lesser of its ultimate fracture strength, Pu, and its jump out strength, Pj. r0.74 D--59 up Yp 1 Pj 0.95 Ajp L Lq l 0-14 d l 0.i4 D-l The strength of a joint with combined bending and tension is found by reducing the ultimate fracture joint strength. Two...
Nonmagnetic Drill Collars
The primary purpose of non-magnetic drill collars is to reduce the interference of the magnetic fields associated with those sections of the BHA which are both above the below the magnetic compass contained in the survey tool with the earth's magnetic field. The non-magnetic collars reduce this type of interference by moving the BHA sections away from the survey compass. There are four critical factors in selecting non-magnetic collars 1 their total length, 2 the location of the survey compass...
REFERENCES Eox
1. Costley, R.D., Hazards and Costs Cut by Planned Drilling Programs, WORLD OIL. Oct., 1967, p.92 2. Crittendon, B.C., The Mechanics of Design and Interpretation of Hydraulic Fracture Treatments, JOURNAL OF PETROLEUM TECHNOLOGY. Oct., 1959, p.21 3. Mathews, W.R. and Kelly, John, How to Predict Formation Pressure and Fracture Gradient, OIL AND GAS JOURNAL. Feb. 20, 1967 4. Hubbert, M. King and Willis, D.G., Mechanics of Hydraulic Fracturing, TRANSACTIONS AIME. 1957, V. 210, p.153 5. Eaton, Ben...
Woods Aerated Mud Equations
In the following equation X is the depth in the annulus at which pressure P is generated. In practice the air mud ratio is adjusted until the desire pressure a depth is attained. The equation is also helpful in selecting setting depths for parasite strings. B A- C . A C P2 2CBP CB2 A C 2 A C 2 e A C PQ2 2 C B P0 C B 2B AC 1 2 r, .i A C P CB . . 0 I tan i o - tan A C 2 B A C 172 P0 annular pressure at the surface, psia. X depth at which pressure P occurs, ft P bottom-hole pressure at X , psia....
Turbulent Cementation Variables
5 High circulating bottom hole The cement bond log shown in the turbulent flow cementation figure illustrates better bonding where the smaller hole diameter exist At depths of 5720' - 57501 the hole diameter is 24 or greater and less bonding has taken place than at the depth of 56951 where the hole is 13 1 4 diameter. The data for the calculations of the Reynold's numbers were taken from the figure. Casing TD is 6482 Cement Class fG', 15.9 ppg, PV 8, YP 12 Mud Fresh water gel with polymer, 12.2...
Casing Tally
An example problem is presented to illustrate the problems encountered in making a casing tally and the subsequent location of centralizers on the casing string. Caution must be exercised in regard to any attempt to set the casing shoe near the bottom of a drill hole. The depth of the bottom of a hole as determined by the strapping of a drill string while in tension or in the derrick may disagree by as much as ten feet with its depth as determined by a casing tally. Logging cables give similar...
Example Of Casing Stress And Deformation
7 casing is in 200,000 lbs of tension in a 20 deg lOOft dogleg. What is the reduction in the diameter of the casing and the maximum axial stress in the wall of the casing The 20 deg lOOft and V by 6.538 casing chart shows a reduction in diameter of 0.13 inch and an axial stress of 90,000 psi. CASING STEEL. 7 6.336 INCH. 0.332 INCH WALL THICKNESS COUPLING STEEL. 7.656 INCH OD, 9 INCH LONG O.'O 0.1 0.2 0.3 0.4 0.5 REDUCTION IN DIAMETER. IN O.'O 0.1 0.2 0.3 0.4 0.5 REDUCTION IN DIAMETER. IN...
Directional Well Planning Section Views
vtod a d f vtoh a d f abs H bg selected deg ft dg selected deg ft tvd selected ft dep selected ft kop selected ft hang selected ft hang angle selected deg target tvd selected ft target dep selected ft rb 180 n bg ft rd 180 it dg ft rd 0.0 for slant well a kop - rkb b rb 1 - cos 0 c rb cos 0 d rb sin 0 e b n boh -toh m n cos b p n sin b k rd cos 0 l rd cos b - cos 0 j rd sin b h rd sin 0 - sin 3 DEPARTURES AT END POINTS OS E DEPARTURES AT END POINTS OS E measured dephts at end points mtos a 0 it...
EXAMPLE Nym
API casing couplings on 9 5 8 casing have a diameter of 10.625. What diameter drill collars must be used to assure that the 9 5 8 casing can be run into a hole drilled with a 12 1 4 drill bit Required Collar Diameter 2 10.625 - 12.25 9.0 in Minimum Drill Collar Diameter while Drilling with Slick or Pendulum BHA
Example Of Allowable Drilling Torque
While drilling in the rotary mode with 5 by 4.276 drillpipe and a tension of 100,000 pounds, what is the maximum allowable rotary torque Let the BHAs connections be 5.5 API REGULAR on 7 by 2.5 collars. The make-up torque for rotary shouldered connections stresses the steel to 62,500 psi which is about 50 of the steel's unit yield strength. The make-up torque for a 5.5 API REGULAR connection is 39,000 lb-ft . The make-up torque of 5.5 Full Hole, premium class, tooljoint is 28,800 lb-ft. The...
Api Collapse Resistance
The API Bulletin 5C3, fourth edition, February 1, 1985, recommends four equations for computing the collapse pressure resistance of tubulars. The choice of equations is based only on the D t ratio of the tubular. Equation 1 is a theoretical equation which is based on the yielding of the inner wall of a tubular. It is Lame's equation and it is well known in the literature of mechanics of materials. Equation 2 is an empirical equation which was derived from collapsing 2,488 tubes composed of...
Weight on Bit in Vertical Holes
The statement only the buoyed weight of the BHA should be placed on the bit is correct. Only using the buoyed weight of the BHA on the bit will prevent the drillpipe from axially buckling and most likely also prevent it from torsionally buckling. It is not true that the drillpipe is in tension just above the BHA. The normal portions of the drill string which are bent, straight, compressed and tensioned are shown in the figure. Note the section which is in compression and is straight. The...
FISHING DRILL COLLARS and DRILLPIPE
Two important problems can surface in the fishing of drill collars and drillpipe. One is that drill collars which are off bottom can fall to the bottom of the hole after they are washed over. The other is that the top of the collars, if free, can lean over in an enlarged hole or under a ledge and make it impossible to get over them with tools. The first potential problem of letting washed over collars or pipe fall to the bottom of the hole may be circumvented withawashover back-off tool. These...
Bit Classification Form
Soft formations with low compressive strength and high driilability Medium to med-hard formations with high compressive strength Hard semi-abrasive and abrasive formations Soft formations with low compressive strength and high driilability Soft formations with low compressive strength Medium hard formations with high compressive strenath Hard semi-abrasive and abrasive formations Extremely hard and abrasive formations a. identified by four codes 1 series, 2 type, 3 feature 1, and 4 feature 2 b....
Example Of Iadc Bit Classification
IADC Classification 124E soft formation, sealed roller bearings, milled teeth, with extended nozzles soft formation, sealed friction bearing, insert chisel teeth, gauge protection soft form, insert teeth medium to hard within group
Primary Cementation
1 sack of cement powder plus 5.2 gal of mix water makes 1.18 cu ft of slurry at 15.6 ppg. 231 CU IN 1 GAL 1728 CU IN 1 CU FT Farm Readings 600 72 300 39 200 24 100 17 6 6 3 4 cement collar catches both plugs 2 long shoe 1' long protects end of casing while running it cement collar catches both plugs 2 long HOW MANY SACKS OF CEMENT ARE REQUIRED Cementation time Barrels of mix water Displacement volume Mix time min Displacement time min Bottom hole pressure after all of cement has been mixed The...
Backoff And Free Point Tool Procedures
Selecting a location to back-off a stuck string of pipe is assisted with a free point tool. In most cases the desirable location to back-off will be at a collar just above the stuck point. Situations which may dictate other locations are to back-off inside casing, above a dogleg, above a ledge, or within a gauge hole. Backing-off in an over gauge hole may allow the string to fall to one side prohibiting the latching onto it with an overshot or other tool. The free point tool identifies the...
Casing Program
24 driven to 400' 260' water 140 sea bed 18 5 8 conductor set in 21 hole at 1,388' TVD or l,412f MD 13 3 8 surface casing set in 17 1 2 hole at the top of an over-pressured shale at 3,838' TVD or 5,160' MD 9 5 8 intermediate casing set in 12 1 4 hole at the top of the Danian D1 top at 6,470' TVD or 10,127' MD 6 5 8 liner set in 8 1 2 hole at end of drain hole at 6,537' TVD or 11,818' MD Drilling Mud 21 hole pre-hydrated bentonite unweighted seawater mud 17 1 2 hole native clay, lime, caustic...
Casing Sag Between Centralizers
The approximate sag maximum downward deflection of the casing between the centralizers MD of the pipe is given by the following equation Timoshenko, Strength of Materials, Part 2, page 45, equation 52 WFb sin 0 CS 1296VU2 U cosh U - XJ MD V-EI- Ay sinh U ' TT 36 T CS y U -gj- no units E 30 106 lbffin2 I D4 - d4 in4
Objectives
Objective of Rig hydraulics has eleven facets and one myth 1. cleaning of the bottom of the hole while drilling 3. transportation of solids to the surface at a reasonable rate 4. removal of drill solids and cavings with mud cleaning equipment 5. equivalent circulating density for the prevention of lost circulation 6. running of close clearance tools 7. circulating by close clearance tools 8. friction pressure losses through and around the drillstring and rig piping 9. hydraulic energy...
Requirements for Air Drilling after F W Smith
Drill String amp Well Head Equipment Surface Holes 12 1 4 to 22 Wet or Dry Cutting Deflector Float Valve Bleed Line Under Surface Pipe to 5000' dry 7 7 8 to 9 7 8 Hole Double BOP Rotating Head Float Valve Bleed Line 100' to 300' 7 or 8 5 8 Flow Line Sample Catcher Under Surface Pipe to 5000' wet 7 7 8 to 9 7 8 Mist Drilling Double BOP Rotating Head Float Valve Bleed Valve Under intermedial Casing 2500 to 15,000' dry 7 7 8 to 9 7 8 Hole Double BOP Rotating Head Float Valve Bleed Line Under...
Solve By Trial And Error For
dept- rb ' 1 - cos 0 - rd abs cos b - cos 0 tvd - kop - rkb - rb sin 0 - rd abs sin 0 - sin b rd 0.0 for slant type A directional well plan calls for the enumeration of values shown on the directional plan or the directional drilling plan figures. Three types of directional wells are popular 1 the slant which is the most simple and is shown in the directional plan figure, 2 the S type, and 3 the horizontal or double build type which are shown on the directional drilling plan sketch. Some rules...
Laminar Flow Cementation
The laminar flow technique has the smallest displacement efficiencies 75 and less of the three flow regimes and often gives inadequate cementations. It should be avoided when possible. However, because of equipment limitations and poor planning, the technique is often inadvertently used. MECHANISM ECD is greater than the fracture strength of the hole. SOLUTION Reduce the density of the cement column and the circulating friction pressure loss. See the ECD calculation for the turbulent flow...
Critical Rotary Speeds Of Bha
Rough drilling which results in the shaking of the rig and drill string is created by the drill bit cutting on the bottom of the hole and the natural vibrational frequencies of the BHA and the drillpipe. The vibrations are of both longitudinal and torsional types. It is believed that the roughest drilling conditions occur while the longitudinal or torsional vibration frequencies of the bit are matched by those or one of their harmonics of the BHA or the drillpipe. If the frequencies match they...
Example Transposing Md To Tvd
Find the VPL of a section of 7 casing if it lies between 1,500' MD and 14,000' MD. Once again use the data given for the preceding example S type well. VPDtop 1000 53- sin 1500 - 1000 .03 1,494 ft VPDbot 10,201 sin 46.39417- sin 46.3917- .07 14000 - 13882 VPLr. 10,288 -1,494 8,794 ft The collision problem is the problem of ascertaining the three dimensional distance between drill holes. Because surveys are normally referenced to the rotary kelly bushing, rather than a common point called a tie...
Equivalent Circulating Density
The equivalent circulating pressure, ECP, is the sum of the circulating friction pressure loss in the annulus and the static pressure of the mud above a selected location in the drill hole. Most often the circulating pressure friction loss is computed with the powerlaw model as illustrated earlier in this chapter. The equivalent circulating density is thought of as a static mud column from the selected location up to the surface which will create a pressure equal to the ECP. A mud which has a...
Friction Factors
Coefficients of friction between the drill string and drill hole with unknown cuttings bed packing, which are often called friction factors, have been reported in the range of 0.24 to 0.28 by north sea operators. Gravity pulls pipe and BHA's only toward the center of the earth. Friction between the wall of the hole and the drill string vanishes becomes zero during the rotation of the drill string. All of the weight of any part of the drill string which is in a hole where the inclination is 90...
Tubing Movement And Stress Computations
Tubing designs are resolved with the paper written by Lubinski, A., HELICAL BUCKLING OF TUBING SEALED IN PACKERS, AIME TRANSACTIONS Jornal of Petroleum Technology , JUNE, 1962. The following problem is one in which tubing is used to squeeze cement casing perforations. The following assumptions, which are standard in most tubing design methods, are made the tubing fills with the fluid which is within the casing as it is run no surface pressures are applied while running the tubing no snubbing...
Viscous Drag Pressure Surge Equations
The pressure surge equations are those published by J. Burkhardt LAMINAR MUD FLOW IN THE ANNULUS PL G B FV VP 3.3 TURBULENT MUD FLOW IN THE ANNULUS 1.0 if pipe is closed at the bottom values from charts if the pipe is open or partially laminar pressure surge per 1000 feet of pipe lowering or raising velocity of the pipe feet per yield point of the mud lbf 100 sq. ft diameter of the hole bit diameter inches effective diameter taken from the chart inches outside diameter of the pipe inches...
Weight on Bit in Inclined Holes
In inclined holes sources of available weight which may be placed on the drill bit are the BHA and the drillpipe. The available weight from the BHA is reduced because only a fraction of the weight of the BHA acts in the direction of the bit. In inclined holes drillpipe weight can be placed on the drill bit because complete helical buckling of the drillpipe is delayed by the effort required to lift the drillpipe to the high side of the hole. Once the axial load in the drillpipe exceeds its...
Placement Of The Pendulum Stabilizer
One of the most important functions of stabilizers is to assist the bit in the drilling of a more vertical hole. The pendulum BHA as illustrated in the figure is superior to other designs. The principle of the pendulum BHA is to place the centralizer at a location in the BHA such that the point of tangency of the BHA does not contact the wall. This will maximize the pendulum force which swings the BHA back to the vertical. In addition to the location of the stabilizer the other important...
Maximum Available Weight For The Bit
The maximum available weight for the drill bit, which may be generated by the drill string, is the sum of the buoyed weights of all the sections multiplied by their true vertical lengths. The equation is max. available weight for the drill bit lb buoyancy factor air weight of a section of the drill string lb ft true vertical length of a section ft index representing each section of the drill string
Example Available Weight For Bit
Let the KOP point be raised to a depth of 100 feet in the previous example and let the drag in the hole be 20,000 pounds while not rotating. Other variables are unchanged. Wt. 1 - gg g 21.6 100 1,204.04 The available weight for the drill bit is 23,432 pounds while rotating and may be sufficient but while not rotating only 3,432 pounds are available which is not sufficient after deducting the drag. A solution is to run heavy weight drill pipe 50 lb ft . The heavy weight drillpipe will provide...
Cost Per Foot Equation
The cost per foot equation is used for the comparison of alternative equipment, chemicals, and procedures for the drilling of a formation or an interval. The comparisons are often called break-even calculations and are usually between drill bit types or manufacturers however, any of the variables may be compared. Bit Tools Mud Drill Time Trip Lost Rig Support Tool Rental C Drill Rate Drill Time C Cost per foot for the interval of concern ft Bit Cost of delivered bit at the drill site Tools Cost...