## Tubular End Conditions

The ends of tubulars (top and bottom of the casing) may either be fixed or free. The bottom end is usually free until cemented and the top end is free until the wellhead slips are set. These conditions are tubular end conditions. The common practice in tubular design today is to design tubulars as if both ends were free. Of course, in stability analysis for buckling and loads, the critical conditions are when both ends are fixed. This condition only occurs after the tubular has been cemented...

## Cementation Temperatures

Cooke (EXXON) measured downhole temperatures and pressures during a primary cementation. Six temperatures and pressure sensors were attached to the outside of 2 7 8 casing at the depths shown on the chart. Bit diameter was 7 7 8. A slurry volume of 390 barrels of 16.6 ppg Class H cement plus sand was circulated to a depth of 1,200' in the annulus. The three axes of the chart are sensor temperatures in F, geothermal temperatures at each sensor in F, sensor pressures in 1000 s of psi, and time in...

## Info

*Indicated maximum can be increased via installation of rotor nozzle **Operating above this level can shorten tool life. ARTICULATED DRIVE PIPE ROTATED THROUGH CURVE) 3' System 4Vi System Maximum Temperature F. C) Maximum Liner Pressure ps Bar) Length (ft. m ) Approximate Weient Jb.-ft. Kg. m.) CONNECTIONS v Box Up Recommended Make Up Torque (ft.-lb. Nm) 4l j 17,* 260 127 1500 103 20 6 Type OD un ) ID un Drift vin.) Length Ji -m Approximate Weight (lb.-ft. Kg. m.) CONNECTIONS Recommended Make...

## Air Weight

The air weight of drill collars is the natural attraction of the earth for the steel comprising the collars. A convenient equation for computing the air weight of collars is Ws air weight of collars lbs D outside diameter of collars inch d inside diameter of collars inch L length of collars feet .2832*12*4 *(D2-d2) 2.67 * (D2 - d2)

## EXAMPLE

Compute the maximum jar triggering load if 90 feet of 8 * 3 * 147 ppf drill collars and 8,000 feet of 35 worn 5 * 19.5 ppf* E grade drillpipe (actual weight is 21 ppf) is run above the jar in 11.0 ppg mud. The maximum triggering load without hydraulic pressure assistance is the difference between the tensile strength of the drillpipe and the buoyed weight of the string above the jars. If the hydraulic pressure is assisting the triggering of the jars then the pressure-area force created by the...

## Concentric Prit I Pipe And The Jet

Binkley published a description of the concentric drillpipe system and the operational problems associated with drilling a hole from 12,630 feet to 14,866 feet. The concentric drillpipe and equipment are shown in the sketches. CONCENTRIC DRILL PIPE AIR t-I T METHOD y COtJC NTRlC FLASH WELD DSILL PIPS y COtJC NTRlC FLASH WELD DSILL PIPS

## Example Horizontal Separation

The horizontal distance between two drill holes are to be computed at a true vertical depth of 1,000 feet relative to a tie point.The coordinates of the RKB's relative to the tie point are given in the table. The coordinates of the borehole which are interpolated with the Sectional method, referenced to the tie point, and shown on the following pages are Coordinates of Hole 1 N E V

## Rig Hydraulics

Effect of Mud Weight on Bit Bingham's Drilling efficiency Optimal Bottom Hole Theory of Maximizing Impact Effect of Mud Weight of Bit Hole Drill Cuttings concentration in the Hopkins Particle Slip Velocity Oribital Motion of the Drill Surge and Swab for Long Pipe Surge and Swab Pressures of Short Circulating Pressures for Short Equivalent Circulating

## Net Available Weight For The Drill

The net available weight for the drill bit is the sum of the products of the buoyed weight and the true vertical length of each section of the drill string minus the axial friction which the section generates. The equation is AWOB max. available weight for the drill bit lb Bf buoyancy factor Ws air weight of a section of the drill string lb ft TVL true vertical length of a section ft Ff axial friction acting on a section lb i index representing each section of the drill string

## Hydraulics For Horizontal Holes

Cleaning of inclined and horizontal holes presents two major concerns which are not present in vertical hole cleaning. One concern is the existence and thickness of a bed of cuttings on the low side of the hole. The other is the sliding of a bed of cuttings down hole. In regard to sliding, a bed is said to be stable if it does not have a tendency to slide and unstable if it does. Having a cuttings bed in the hole while drilling places the tripping of the pipe in jeopardy. Larger mud pumps are...

## Oil Well Drilling Bit Performance

7 Integral Blade Pony Collar Stabilizer Achieved Dogleg While In Sliding Mode ( 100 Ft) Lower Bearing Housing 6 1 2 Watermelon Stabilizer PDC Bit i Achieved Dogleg While In Sliding Mode ( 100 Ft) Achieved Dogleg While In Sliding Mode (7100 Ft) 4 3 4 Short Directional (DIR), Low-Speed Downhole Motor 4 3 4 Short Directional (DIR), Low-Speed Downhole Motor Achieved Dogleg While In Sliding Mode (7100 Ft)

## Original Directional Survey

ADJUSTED POSITIVE DIRECTIONAL SURVEY (+0.4 An experiment conducted with 34 students (each with 3 years of engineering training) who were asked to read and record independently with the aid of a ten power magnifier (standard reader) the direction and inclination on a survey film disc demonstrated that the expected direction value read would be 0.75 degree of the average value read by the group 95 of the time read and 0.5 degree for the inclination angle. The disk could record inclination angle...

## Hole Angle And Class

8 with Stabilizer at Height Shown 8K2 with Stabilizer at Height Shown 9 with Stabilizer at Height Shown 9y2 with Stabilizer at Height Shown 10 with Stabilizer at Height Shown lO' z with Stabi lizer at Height Shown The response of rate of penetration to weight on bit per inch of bit diameter is linear for most drilling operations. Thus, the relative penetration rate for the 12.25 hole of question number three and the 8.75 hole of question number four is T* i T> f -BIT DIA.J1 12.25 Relative...

## Magnetic And Other Interferences

The magnetic compass is an instrument with a suspended bar magnet which aligns with the resultant direction of all magnetic fields by which it is influenced. Errors in directional wellbores which occur through the magnetic compass are caused by the lack of compensation for spurious magnetic fields. The steel in the drillstring is a magnetic material and the affect of its magnetic field is minimized by lengths of nonmagnetic drill collars which remove the survey compass from the magnetic steel...

## Example Of Fracture Gradient

Calculate the fracture initiation and extension gradients at a depth of 8,000 feet. Use the approximations to Ben Eaton's data. Sob VOBG 0.84753 + 0.01494 * 8 - 0.0006 * 82 + 1.199E-5 * 83 .935 psi ft (also known as s0b) v 0.23743 + 0.05945 * 8 - 0.00668 * 82 + 0.00035 * 83 - 6.71E-6 * 84 MWE 14 ppg (taken from the sketch at a depth of 8,000') MWE. -f (.935 - .052 * 14) 1 'AZL + .052 * 14 + MWE , (.935 - .052 * 14) ' ' + .052 * 14 + ext 1 - .437 8000 .901 psi ft or 17.34 ppg

## Example And Equations

117188 * 4.5 * 7.6562 - 6.903372 6.90337 * 7.6562 P internal pressure leak resistance of couplings psi A hand tight standoff turns (Std 5B) El pitch dia. at hand tight plane inches (Std 5B) 630337 For Buttress thread casing use 3000000 * .0625 * (1 + 1.5) * 7.6562 - 6.9542 .

## Surface And Dogleg Running Loads In Directional And Vertical Holes

Tubulars have been broken and parted while being run. Axial tension loading, at any one point in the tube, may be at its highest intensity while that point is being lowered through the rotary table. Further, if a tube enters a dogleg, an additional bending load must be added to the tension load. In directional holes, the true vertical length of a section of tube changes as the section passes from one position to another position. Thus, the tension at one particular point in the tube changes...

## Fishing Logging Tools And Wire Line Tools

Wire line logging tools and other wireline tools are usually less than forty feet in length and three inches in diameter. Three prevalent causes for fishing these tools are differential wall sticking, cavings which wedge them in the hole, or junk falling into the hole on top of them. In most cases if the cable were stronger the tools could be pulled with the cable on which they were run. The usual fishing operation is running into the hole with pipe, latching onto the tool, pulling it free, and...

## Declination Changes

The direction of tho magnetic forco at Lv> (After L A. Bauer) The direction of tho magnetic forco at Lv> (After L A. Bauer) showing the direction of the earth's magnetic force at London, England, from year 1540 to 1935. Note the maximum change in declination was 35 and 8 in inclination.

## Kill Well Design

A kill well is to be designed for directional considerations. The kill borehole is to intersect the well which is blowing out (its design is given below) 200 ft TVD above the top perforations in the blowout well and then follow the blowout well to its bottom. Later the casing of the kill well will be perforated opposite the perforations of the blowout well and the well killed with mud. Completing the table will provide the directional considerations required.

## Internal Yield Pressure Of The Wall Of The Tube

The internal yield pressure (burst) of the wall of a tube is given by the following API formula. The factor 0.875 accounts for the minimum wall tolerance. This is the thin wall formula of mechanics and loses accuracy as walls thicken. P internal yield pressure of the wall psi Yp yield strength of the steel psi t wall thickness of the tube inches D external diameter of the tube inches Compute the internal yield pressure for the wall of 7 6.276 26 ppf LT& C N-80 casing. t 0.362 The API lists...

## Barrels Of Mud Pumped To Remove Kick

ENGINEER'S METHOD ENGINEER'S 4,106 PSI 15.79 PPG, DRILLER'S 4,142 PSIG 15.93 PPG 1000 2000 3000 4000 5000 6000 DEPTH IN HOLE OF MAXIMUM PRESSURE, ft 1000 2000 3000 4000 5000 6000 DEPTH IN HOLE OF MAXIMUM PRESSURE, ft KICK REMOVAL WITH THE DRILLER'S METHOD 1400 -r 1200 - 1 000 800 --600 100 200 300 400 500 VOLUME OF MUD PUMPED, bbl

## Intermediate String Burst Load Lines

The high burst ratings required are difficult to obtain for the large diameter casing required to allow setting multiple liners. Additionally, the gas to surface criterion would require 15000 psi blowout preventers. Even the water to surface burst condition is difficult to achieve. There are two ways gas to surface can occur. A gas bubble can be allowed to rise to the surface with the well shut in or, with a drillpipe kick, the drillpipe parts or is sheared near the surface. An underground...

## STEPS in the Cable Guide Method

Pull the slack out of the cable, and cut it about 3 to 4 feet above the rotary table. 2. Attach a line clamp to the cable and let the clamp rest in a guide base which has been placed on the rotary table. 3. Attach a fishing spear rope socket to the end of the line which is in the hole. Attach a rope socket with threads to the end of the cable which is in the mast. * 4. Make-up a sinker bar and an female spear overshot to the threaded rope socket. The sinker bar will be used to drag the free...

## MWE c ppg at ft

Thus caution must be used in order to prevent zones high in the hole from kicking. V0 volume of oil pumped bbls V volume of mud pumped behind oil bbls Can annular capacity bbls foot Cp pipe capacity bbls foot MWE mud weight equivalent at a particular depth ppg D depth to stuck zone or total depth feet Pg pressure within the pipe at the surface psi

## Latching And Unlatching Procedure

Exact measurements of the depth of the top of the fish and the length of the fishing string are best. Lowering the overshot onto the fish must be done with precision in order to avoid flaring or otherwise damaging the top of the fish. The overshot should slide over the top of the fish with one point of weight or less. If higher weight is needed to force the fish into the overshot, then the overshot may not release the fish at a later time. To correctly latch onto a fish, the overshot should...

## Filling Of Fracture Elastic Rock Deformation

1 2 3 4 5 6 VOLUME OF MUD PUMPED (EEL) Pressure integrity tests are conducted to ascertain the resistance of a formation penetrated by a wellbore to the initiation of a fracture within the formation. There are two phases of fracturing a formation the fracture is initiated and then extended. The pressure required to cause initiation of a fracture is usually greater than the pressure causing extension. A pressure integrity test is a test in which the drill hole is pressured at the surface by...

## Fdv

Calculate the formation abrasiveness coefficient (A). T * i step 8 * step 16 12 * 143 A m * U step 14 * step 18 .404*1834 21. Calculate the formation drillability coefficient (C). F * i step 20 * step 17 * step 13 * step 14 * step 19 2.32 * 31.8 * 31.5 * .404 * 967 22. Calculate the drilling fluid coefficient (S). B*L step 12* step 15 4 8*2316 1,04 23. Calculate the cost parameter (G). 24. Calculate the normalized chart coefficient (An). 25. Calculate the normalized chart coefficient (Sn)....

## Example Of A Single Build Well Trajectory

A single build horizontal well is to be planned with KOP I the following data. At what depth is the KOP and at what departure does the horizontal section begin Build Gradient 12 deg lOOft to 90 deg TVD of the horizontal section 7,000 feet Thus, the KOP is at a depth 6,522.54 feet (7,000 - 477.46) and the departure of the beginning of the horizontal section is 477.46 feet.

## Multiple Regression With Least Squares

Multiple regression is used to find the parameters of an equation which causes the equation to best represent the data. If a computer is available an alternative which is not associated at all with multiple regression and is very powerful is the table look-up method. The multiple regression method is illustrated with two independent variables, X, Z, and three parameters, k, b, and c. Compute k, b, and c with the least squares method for this popular engineering equation. Begin by putting the...

## Time Value Of Money

Because interest is paid on savings, the value of money varies with time. Suppose that a company has had an average rate of return of 21 over the past five years. Further, if an employee had bought a stabilizer five years ago for 1,000 and did not use it, what would its value need to be today to break-even The equation for computing the time value of money is the following. V Value of principal five years later and is unknown P Amount of dollars spent five years ago 1,000 r Yearly rate of...

## Example Wear Problem

7 23ppf 6.366 ID 40 foot long casing is worn in a cresent shape to a depth of 0.0234 inches by 3.5 drillpipe which has 5 tooljoints. How many cups of steel is contained in the cresent Radius of tooljoint 2.5 in. S .7064 in. 3 0.0639 radian A2 1.1554 sq. in. A3 0.2542 sq. in. Ac 0.0227 sq. in. 0.0227 * 40 * 12 10.896 cubic inches Ifi The literature identifies three wear phenomena by which steel is removed from the wall of casing 1. lubricated friction wear at low contact pressures between smooth...

## Conveyed Logging Also Called Wet Connect

A popular logging system in horizontal wells is the pipe conveyed tool system. The pipe conveyed system makes use of a side entry sub and a device for attaching the logging tool to the end of the pipe. The pipe is usually drillpipe. The device is called a release tool. The following steps explain the procedure. 1. The logging tool with the logging line release tool is attached to the drillpipe and run into the hole. 2. The logging tool is run to the top of the interval to be logged. 3. A side...

## Latching Onto The Fish

The most popular tool for latching onto fish is the overshot. The overshot allows near full circulation rates, has high tensile strength for pulling heavy loads, and permits long periods of jarring. However, less popular latching tools such as, the inside tap, the outside tap, and the spear, may be functional. The significant limitations of the overshot are that it requires a significant diametrical clearance between the inside wall of the hole and the fish. In order to latch over the fish, a...

## Example Mud Weight On Bit Horsepower

A pump is capable of a pressure of 2000 psig at a circulation rate of 400 gpm. Friction loss is 1000 psi and the mud weight is 12 ppg. Calculate the available bit hydraulic horsepower if the mud weight is increased to 15 ppg and the circulation rate remains at 400 gpm. New friction loss 1000 * ( T 1195 psig New pressure for bit 2000 -1195 805 psid If the jets on the bit are enlarged, then 805 * 400 and 45 hp are lost to the additional friction of the heavier mud. (Common fluid mechanics...

## PfPdPiPrds

Vrds Volume of new drill solids which are not separated from the mud (retained) bbl Wrds Weight of retained drill solids lbm L Length of section drilled ft Effsre Efficiency of solids removal equipment fraction SG Specific gravity of drill solids ppg ppg pw density of water (350 ppb) (8.33 ppg) (62.3 ppcf) pb Density of barite (1488 ppb) (35.43 ppg) (265 ppcf) AVmud Increase in mud volume during the drilling of the section bbl Srds j Recirculated drill solids concentration at the beginning of...

## Salt And Diaperic Shale

The basic guidelines for preventing collapse caused by plastic salt are as follows in order of decreasing priority 1. Drill a gauge hole through the salt. Two completely different mechanisms may responsible for casing collapse. A third is indirectly responsible, but may be the more prevalent cause of failure. Two of the mechanisms are shown in the sketches A good sheath of cement reduces the point loading and makes the external load more like hydrostatic pressure. The best results are obtained...

## Possible advantages of air drilling are as follows

Penetration rates are increased several fold. 3. Straighter holes are drilled because of lower required bit weight. 4. Tight hole problems may be reduced. 5. Differential pipe sticking is eliminated. 6. Lost circulation may be reduced. 7. Borehole diameter may be controlled more closely however, erosion of the borehole can be a problem. 8. Water for drilling is reduced. 9. Daily maintenance costs of a mud system are reduced however, a reserve of drilling .mud must be maintained for well...

## Blowout Control

If a hole is shut-in because of a gas kick entering at the bottom of the hole while drilling, the gas will continue to enter the hole until the pressure at the bottom of the hole is equal to the pressure of the kicking formation. The gas which entered the hole during the early period must be repressured to the formation pressure. This is the primary reason that the pressure gauges rise slowly to equilibrium pressures. If a formation fractures, the pressure in the annulus is relieved, mud and...

## Class A Cement With Salt

Salt Cement slurries are recommended for use in cementing through salt sections, shale formations, bentonitic sands as well as other types of formations that are susceptible to fresh water contamination. When salt is preferentially dry blended with cement. V4 lb. of D-AIR 1 (Part No. 70.157641 per sack is recommended to reduce foaming of the slurry. Where blending facilities are not available and the salt must be placed in the mixing water. I quart of NF-l tPart No. 70.15492 per 1.000 gallons...

## Gilsonite Cement

Gilsonite is a special type of solid hydrocarbon (asphaltite) used with cements to reduce slurry weight and minimize lost circulation. It is a black granular material having a specific gravity of 1.07 and a relatively low water requirement (2 Gals, per Cu. Ft.). It has a bulk density of 50 Lbs. per Cu. Ft., and is supplied in 100 pound paper bags. The following recommendations should be noted 1. Bottom plugs should not be used ahead of Gilsonite cement. 2. A viscous slurry should precede the...

## Rate Of Penetration

C correlation coefficient called the formation drillability factor The values of a and (3 range between .6 < a < 2.0 .4 < (3 < 1.0 p 1.0 if flat tooth wear (non-sharpening) Integration of the tooth wear equation gives bit rotation life (time) RT AyJadD Substitution into the bearing wear equation for differential time (dT) gives the bearing wear in terms of tooth dullness. F gdT CW Ay ja dD The total cost per foot equation is EQUATIONS FOR THE PARAMETERS, G, A, C, & S These parameters...

## Example Of Optimum Pit Dimensions

The perimeter of a rectangular mud pit is to be 144 ft. Its depth is 8 ft. What should its length, L, and its width, w, be to maximize its volume Identify the objective equation it is, f 8 w L. The objective equation gives the parameter to be maximized. Identify the constraint equation itisg 2w + 2L - 144. The constraint equation limits the values of the independent variables which are w and L. Lagrange's equation is the following. Take partials of f and g, and substitute into Lagrange's...

## Example Trajectory Displacements

Compute the displacements between the two stations with the Radius of Curvature method. ___ Dep ( cos 25 - cos 23 ) 37.09 180 91 19 ATVD 2 ( sin 25 ' sin 23 83.30 AN (sin59-sin56) 19.93 n o NOTE Other quadrants may require altered equations. SURVEY TABLE Declination 1 2 Target Azimuth N 71.42 E LONG'S METHOD AND MINIMUM CURVATURE METHOD Roy Long invented a survey calculational method based on an oblique circular arc. He called it the sectional method. His final equations are identical to those...

## Drill hole directional surveys

Gyroed the 24 through drillpipe following the first gyro single shot orientation of the 21 kickoff assembly gyro s and orientation of 21 kickoff assembly until clear of possible magnetic interference from nearby wells MWD surveys for balance of 21 interval and through the 17 1 2, 12 1 4, 8 1 2 intervals magnetic multi-shots (electronic) of 17 1 2 and 12 1 4 intervals during trips at the 13 3 8 and 9 5 8 setting depths gyro multi-shots inside 18 5 8, 13 3 8, and 9 5 8 casings when set

## Solids Concentration Selection

The selection of the concentration of recirculated drill solids to be maintained in the mud can be based on minimum drilling cost per foot. The basic equation combines the cost of the rig, tools, services, and mud for the drilling of a section of hole. The optimal solids concentration equation is cost rig cost + mud cost CPF RRT0pS + MUD CPF cost per foot to drill a section of hole RT& S hourly cost rates of the rig, tools & services g-p ROP rate of penetration of the bit Mud cost of mud...

## Data For Calculating Approximate Circulation Rates Required To Produce A Minimum Annular Velocity Wh

Q (Required cu ft min) Q0 + N * H (Depth in thousand feet) AIR DRILLING 477 MITCHELL Box 1492 Golden CO 80402 Calculate the circulation rate required to air drill 11-in hole with 5 -in. drill pipe at rate of 90 Mir at 11,000 ft. Q Q0 + N*H 1,456 + 135 * 11 2,941 cuft min (after R.R. Angel)

## Directional Variables

Target TVD 6000 - 200 Target DEP Target MD Hang Length 3875 - (6154 - 5800) TAN(49.3418) 7769 - (6154 - 5800) C0s(49.3418) (6154 - 5800) C0s(49.3418) Target TVD Target DEP Target MD Hang Length 5800 ft TVD 3462.83 ft DEP 7225.68 ft MD 543.32 ft MD 5774 ft TVD 4782.83 ft DEP 7900 ft MD 543.32 ft MD

## Drilling Well Walk Tendency

Right and left hand walk is controlled by the rotary speed and the location of stabilizers. The normal tendency for a BHA is to walk right. At lower rotary speeds the tendency is for the BHA to climb the right hand side of the hole and drag the bit to the right, and will do so until the BHA begins to whirl at higher rotaty speeds. Most BHA s will begin to whirl at a rotary speeds of about 90 to 100 rpm in 45 degrees directional holes. The following sketch shows this progression. Once the bit...

## Safety Ring

CASING PATCHES Casing which is rim inside a damaged casing. DIE COLLAR A collar which has internal die thread, for screwing over and onto a fish. GUIDE SHOE A pipe like tool attached to other tools to guide the IMPRESSION BLOCK Usually made of lead. The block is pushed down on a fish to ascertain the fishes size dimensions or state of disarray. JAR INTENSIFIED Also called an accelerator and jar booster. The intensifier gains energy from the pull of the drillpipe and released to the jar. JUNK...

## Iterative Casing Design

The new way considers fictitious loads only to initiate an iterative process which produces the final casing design. The iterative steps are the following 1. Casing of sufficient strengths are selected to overcome the fictitious loads of a. Hanging weight of the casing before cementing b. Burst by formation pressures before cementing c. Collapse by mud or formation pressures before cementing 2. Adjust casing strengths to account for running loads and dogleg running loads if required. 3. Adjust...

## Chapter Vh Horizontal Drilling

Uses of Horizontal Horizontal Types of Horizontal Horizontal Well Casing & Drill bit Directional Drilling subs and Bottom Hole Length of non-magnetic Drill Trajectory Vertical Turn to a New Selection of Mud Drill bit Torque and Friction Buckling of the Drill Lock-up of the Drill Available Torque for the Drill Cementing Cement Sheath within Conveyed Case Austin Chalk Tyra field offshore

## Circulating Pressures For Short Tools

Annular circulating pressure have been shown to be significantly affected by close clearances. This fact is further supported by the following example and is illustrated in the plot on the following page. The pressure loss equations may be simplified for close clearance tools and holes. Entrance and exit effects are neglected. The hole configuration detailed in the previous section is used here. The circulation rate of 400 gpm is used to illustrate the effect of clearance on circulation...

## Enlargement Fracture Of Drill Holes

Drill holes are not 'washed out' by the annular mud stream. Stresses within the wall of a drill hole fails the rock (sand, shale, limestone, etc.) which is the wall of the hole causing this rock to fall into the hole where it is carried away by the annular mud stream. The stresses associated with a drill hole are the overburden, radial, tangential, and mud pressure. A perception of the stresses may be gained by considering the sketch. Sand grains are resting on top of other creating an...

## Fish For No More Than Two Days Without Progress Method

The fish for no more than two days without progress rule is a decision method based on drilling experience. It is a rule of thumb. The following fishing analysis, which is extracted from the morning reports of a real well and shown in the chart, substantiates this rule. In the chart if a sidetrack was not required or the well was not abandoned, then the fish was successfully extracted. Note that those fishing operations in which the fish were not extracted within two days ended in unsuccessful...

## Oilwell Drilling Engineering

Copyright, USA Library of Congress, 1974 to Mitchell Engineering 10th Edition, 1st Revision, July 1995 Dr. Bill Mitchell MITCHELL ENGINEERING 12299 West New Mexico Place Lakewood, CO 80228, USA Email bmitchel mines.edu Tel 303 986 7453 USA All rights reserved. This book or any part thereof must not be reproduced in any form without the written consent of MITCHELL ENGINEERING. Printed in the United States of America. The Society of Petroleum Engineers of the AIME, PO Box 833836, Richardson,

## One Dozen Cementation Problems

There are a dozen major problems which may occur during primary cementations. The following is a list of those problems. 1. Poor displacement of the drilling mud, solids, and cuttings beds over the length of the hole that is being cemented. 2. Lost circulation during or after the cementation. 3. Bridges composed of cement filter cake. 4. Swapping out of drilling mud left below the pipe and cement circulated around the pipe (particularly bad in the setting of open plugs). 7. Permeability after...

## Buckling Of A Gilligan

How much weight must be placed on the bit to buckle the gilligan in 11.3 ppg mud minimum force to bend the gilligan lb OD of gilligan in ID of gilligan in Lubinski s equation predicts the following F 80 * 0.827 (52 + 4.2762) * (52 - 4.2762)3

## Example Gas Column Pressure

If methane gas is drilled at 14,000 feet and the expected bottom hole gas pressure is 9,000 psig at a temperature of 205 F, what is the expected static shut-in pressure The absolute bottom hole pressure and temperatures are PBH 9000 + 14-7 9014.7 psia The critical pressure and critical temperature of methane are Pc 673 psia Tc 343 R The reduced pressure and temperature of methane are 9014 7 The Z factor is taken from the chart where a value of 1.32 was read. 9014 7 Psurf pbh ' P * DEPTH -...

## Stable Thicker

RELATIVE EFFECTS Of PIPE ROTATION ANO VISCOSITY OK BCC THICKNESS RELATIVE EFFECTS Of PIPE ROTATION ANO VISCOSITY OK BCC THICKNESS ic u u tc u rc u AMMUIUS MCUMATIO*. DCC tCl f BOM V TlC l ic u u tc u rc u AMMUIUS MCUMATIO*. DCC tCl f BOM V TlC l University of Tulsa published the chart which shows that the viscosity of the circulating fluid has little influence on bed thickness however, circulation rate appears important. If an oil base mud is being circulated cuttings beds cannot be removed by...

## Example Of Expected Value

A mud company claims that a spending 3,000 more dollars on the mud will cause bits to drill 10 faster and 20 longer. Thus, the values for the data bit adjusted for the new mud are the following. Drill Time Bit life 33 hr * 1.2 39.6 hr Lost Surveying after every trip 0.3 hr Support Contractor and Supervisors 250 Tool Rental Large drill collars 9 hr additional Drilling rate 13 ft hr * 1.1 14.3 ft hr 1491 + 250 + 5000 + 39.6 + 7 + .3 550 + 250 + 9 _ . - 14 3 * 39 6 - 78.91 & tt Because the cost...

## Common Failure Theory Assumptions

The most common simplifying assumptions with regard to tubular strengths are that the failure theory known as the MAXIMUM STRAIN ENERGY OF DISTORTION THEORY1 applies only to tubular collapse strengths and that only biaxial2 loads are considered within the theory. Thus tensile loads and burst loads are thought to be uniaxial3 and strengths are rationalized with the MAXIMUM PRINCIPAL STRESS THEORY OF FAILURE.4 Design factors are usually based on experience. 1 This theory predicts failure of a...

## References

Bulletin on Directional Drilling Survey Calculation Methods and Terminology,, API BULLETIN D-20, 1st Edition, API, Dallas (Dec. 1985). 2. Publication by Eastman-Whipstock, Houston, Texas, W-311 3. Long, Roy C. & Mitchell, Bill Sectional Method A Directional Well Trajectory Computational Model, referred to the Society of Petroleum Engineers, 1987. 4. Wolff, C.J.M. & deWardt, J.P., Borehole Position Uncertainty - Analysis of Measuring Methods and Derivation of Systematic Error Model,...

## Explicit Directional Drilling Equations

_ atan r Pep-e-B -j p. - atan L + f. KOpJ an . r Pep - D cos - B -i rB + D-. 0 90 + atan LtvD + D sin - KOPJ ' acos L_C_J Explicit solutions, similar to those developed below, exist but because they have geometrical constraints which are not easily recognized, they are not recommended. Equations Valid Within Build-Up Section of Hole

## Example Critical Length Radius Of Curvature And Scraping Force

An 8 OD by 3 ID by 30 (360) tool is run in 9 5 8 by 8.535 casing where a 5 deg lOOft dogleg exists. What is the critical length of the tool Lc 2 0.535 (1 * 13,7541 - 0.535) '5 242.6 in U 13,751-0.535-0.5 413,7512-3602 3 2 0.64315 The maximum length of a tool which may be run through an abrupt dogleg without be bent is given by the following equation. Lc critical length of tool in

## Water Shut-off Method For Sand-type Porosity In Air Drilling

Angel, Volume Requirements for Air or Gas Drilling, PETROLEUM TRANSACTIONS. AIME. Vol. 210,1957, p. 325. 2. K. E. Gray, The Cutting Carrying Capacity of Air at Pressure Above Atmospheric. PETROLEUM TRANSACTIONS. AIME. Vol. 213, 1958, p.325. 3. J. A. Krug and B. J. Mitchell, Charts Help Find Volume, Pressure Needed for Foam Drilling, THE OIL AND GAS JOURNAL. February 7, 1972, p.61. 4. R. A. Bobo, G. S. Ormsby, and R. S. Hoch, Phillips Tests Air-Mud Drilling, THE OIL AND GAS JOURNAL....

## Optimal Wob And Rotary Speed Charts

Galle and Woods published charts for the selection of optimal weight on bit and rotary speed. The following steps outline and illustrate their procedure. 1. Get a record of the bit's performance and wear data. 2. Record bit size (d) and type _8 - 3 4 OSC 3. Record hourly operational costs (C0pr) _50.00 hr 4. Record bit cost (C ) _200.00_ 5. Record the bit depth in 10.000 feet and depth out 10.180 feet. 6. Record the round trip time (t ) for the bit 6 hrs 7. Record the bit footage (F) 180 feet_...

## Tubular Design And

Tubular Design and Failure Tubular End Names of Salt and Diaperic Casing Design Management's Popular Design Drilling Burst An Overview of Casing Minimum Tubular Failure Triaxial Real Fundamentals of Stress Effective Buoyed Free Stretch and Wall Change in the Diameter of a Bending Stress in Lubinski Bending Buckling v. Tension & Critical Buckling Events of Buckling Tendency & Wellhead Intermediate Casing Tubular API Collapse API Internal Pressure Pipe Body Yield API Hydrostatic Test...

## Vertical Turns To A New Track

The Mitchell Engineering computer program VER_TURN.XLS can assist in the design of the drill hole. The program requires the following. 1. Inclinations of the drill hole at point 2 and 6 2. Turn gradients (build and drop) between the points 2 and 3 and points 4 and 5 3. Length and inclination of the tangent section between points 3 and 4 The program computes the departures and TVD's of the individual sections and the total departure and TVD of the turn. The measured depth length of the entire...

## Solutions To A Dozen Problems

1 PROBLEM POOR DISPLACEMENT OF MUD MECHANISM The volumetric fraction of the mud removed from the wellbore annulus by the cement slurry is called displacement efficiency. High displacement efficiencies increase the probability that the set cement will not contain channels of mud or that the cement will not have channeled through the mud. Satisfactory displacement efficiencies depend on many factors however, the type of flow regime in which the cement slurry and the mud being displaced is...

## Confidence Lines

Confidence lines are computed and drawn to provide the following type of answer 'if 100 holes are drilled, 95 of the holes will have an expected maximum cost of 125,000 per hole and a minimum expected cost of 75,000 per hole and an expected cost of 100,000 per hole'. These are often called the maximum, minimum, and best values. Draw two confidence lines and the least squares line for the linear equation Y a + b X Begin by computing a, b, and c X, Y are data point pairs N is number of data point...

## Kick Removal

The driller's and engineer's removal methods are two reliable methods of circulating a drilling kick from a hole. The other methods presented below are satisfactory in special circumstances. The depicting attributes of each method are the following 1. kill mud is pumped after the kick is removed from the hole 2. two circulations of the hole are required 3. annular and surface pressures will be higher while removing the kick than those of the engineer's method 1. the drilling mud is weighted to...

## Table Of Survey Computations

Target N +3,612 E +4,173 TVD +5,638 MD sin I cos Az MD sin I sin Az MD cos I AN + N AE + E ATVD + TVD sum of AMD 91 sin 34 cos 39 91 sin34 sin 39 91 cos 34 39.54 + 548 32.02 + 341 75.44 + 989 91 + 1684 ADep yj(N2 - Ni)2+ (E2 -E1)2 V(587.55 - 548)2+ (373.02 -341)2 Cum. Dep sum of ADep 717.00 + 50.72 5519.10 91 34 39 39.55 32.02 75.44 Min. Hor. Turn Grd. to Target Mitchell Engr. Prog. Lead_Tgt.XLS 0.51 deg lOOft Min. 3d Turn grd. to Target Mitchell Engr. Prog. 3d_Plan.XLS 0.45 deg lOOft The...

## Filling The Hole On Trips

Pulling of the pipe from the hole on trips causes the mud level in the hole to drop unless it is being continuously filled. The best procedure utilizes a trip tank because the trip tank allows precise accounting of the mud entering or leaving the wellbore. Regardless of the procedure or equipment used, when a stand of drill pipe is pulled from the hole, the volume of the steel of the drill pipe must be replaced by mud. Density of steel is 2,749 pounds barrel. weight per foot of pipe (lb ft)...

## Hopkin S Slip Velocity

Compute Vfc with Mitchell's equation if a 17.5 drill bit is drilling at a rate of 100 fph. The mud circulation rate is 1,148 gpm and the API yield point of the mud is 30 100sq.ft. The drillpipe is 5 arid the mud weight is 9.3 ppg. Connection time is 3 minutes. The bottom hole assembly is 9.5 in diameter. Spheres of a diameter of 0.95 are to lifted. The slip velocity read from Hopkin's chart is The correction factor for the mud weight is F_x, 2.117 - 0.1648 * 9.3 + 0.003681 * 9.32 0.903 The...

## Criteria And Equations For Casing Design

Design criteria are different from management's guidelines in that the criteria are specific to loads and casing strengths. Mathematical equations are derived from criteria, not precepts of risk and cost. Every designer must envision the maximum tensile loads and their backups, maximum burst loads and their backups, and maximum collapse loads and their backups, for every foot over the length of the casing. Then the designer must match those loads with sufficient strength casing. All equations...

## Torsional Dampening Fly Wheel Effect

Flywheels are used to dampen torsional vibrations, such as the flywheel in a car engine. They do this by removing the high peak torsional energy variations. In the drilling operation variations in torsional energy within the drill string are caused by the drill bit, stabilizers, and the rotation of the BHA and drillpipe. Large drill collars act very well as flywheels. The equation for the dampening variable or the flywheel effect is N * Jc * Lc Jc polar moment of inertia in Lc length of...

## Drill String Measurements

Perhaps the best procedure for measuring the length of a drillstring is to strap the string while pulling it out of the wellbore with the string hanging on the elevators and after rotating each stand free of wellbore drag. In vertical holes this procedure should very accurately give the length of the drillstring and then the measured depth of the wellbore and it should be sufficiently accurate for most directional wellbores if not precisely correct in principle. EXAMPLE CHANGE IN LENGTH OF BHA...

## Drill Solids Optimization

Shown below is a sketch of a typical flow loop for rotary drilling rigs. The drill solids are generated by drilling new hole and hole enlargement. Because drill solids accumulate in the annulus, the drill solids are at their highest concentration there. A portion of the solids are removed by the solids removal equipment and a portion are retained. This is called separation of solids'. Because of the difficulties in removing solids, few old solids, i.e., those which have been recirculated and...

## Expected Value Method as a Decision Tool

The expected value method is based on averages and probabilities. The expected value of an event is equal to the probability of it succeeding times the cost of succeeding, added to the probability of it failing times the cost of it failing. The sum of the probabilities of success and failure must have a value of one. The formulas for computing the expected value of fishing is For example it may be reasoned that the expected value of winning on-betting that a tossed coin lands on heads, is to...

## Breakeven Charts as a Decision Tool

Break-even fishing cost is a comparison of the direct costs of fishing with the potential of the salvage value of the fish and the drill hole. For example let the direct fishing cost be 6,000 per day, the fish is a 50,000 bottom hole assembly, 12,000 of hole will be lost, and a sidetrack at a cost 28,000 will be required if the fish is not removed. The break-even number of days of fishing provided that all the fish can be removed by the last day is A popular variation of the break-even chart is...

## R r f kopmi

MDx KOP + asin L- -J Equation Used To Calculate Slant Angle For a slant well ( no hang section) (- DEP4-B - p cosLatan VTVD4 . K0P j 0 90 + atan LwD - KOP-I acos L TVD -KOP J For an S-type well ( hang section is present) 0 90 + atan Ltvd + D sin 6 - KOPJ acos Equations Used To Calculate Coordinates of Point 2 TVD2 KOP + B sin 0 DEP2 B (1 - cos 0) Equations Valid Within Slant Section of the Hole Equations Used to Calculate Coordinates of Point 3 TVD3 TVD4 - D (sin 0 - sin ) DEP3...

## Leading The Target With Planned Walk

The problem is to find the coordinates of any point, such as point 3, on the trajectory arc and the azimuth, angle x, of the tangent line, g, to the arc at that point. Also, the turn gradient will be ascertained for excessive severity. Most often the lead angle, 3, the coordinates of the target, N2 amp E2. and the distance, a, along the chord to a point opposite the point on the arc are given. This means that in the diagram the values to be found are T, N3 amp E3, and the turn gradient i.e.,...

## Procedure

If the cable is not broken and is attached to the tool, the tool can be retrieved directly with pipe, an overshot, and the cable guide method. If the line is broken and has fallen down the hole, then several runs with wireline spears may be required to fish the wire line. After the wire line is fished to the top of the stuck tool, a stout pull will pull the wire line out of the rope socket at the top of the stuck tool. Getting over the stuck tool with an overshot will most likely require a...

## Critical Buckling Load

The minimum load acting on an end of a tube which creates axial buckling critical buckling load is Berit f Bf2 D2 d2 D2 - d2 3 critical buckling load lbs buoyancy factor no units outside diameter of the tube inch inside diameter of the tube inch 80 for 1st order buckling 155 for 2nd order buckling What is the critical buckling load of 8 3 drill collars within 11.3 ppg mud

## Definition Of Terms

Equivalent weight on a 7-7 8 inch bit 1000 pounds Cost rate of the drilling operation hrs Fraction of tooth height worn away 8ths Fraction of bearing life consumed 8ths Galle and Woods published the following relationships for the rate of tooth wear. i N 4.348 105N3 a 1 6D .928 D2 JadD D 3D2 .309D3 Ja115 dD -.0067 1.15 D 0.871 D2 least squares approximation has less W Wactuaj 'gg and is called the equivalent weight A correlation coefficient for tooth wear and is called the formation...

## Stuck Point

8.82E6 Wg ppf AL inches L AFObf 30 106 98.5 - 90.3 L .283 141,000 -121,000 A free body of the drill pipe shows that the hook load required to place the neutral point of axial stress at the stuck point is Hook load 16.6 5010 83,166 lbf Weight Indicator 83,166 18000 101,166 lbf Slacking off more weight than 101,166 lbf will cause buckling of the drill pipe. The change in the length of the pipe will be the sum of the helical buckles and Hooke's Law effects. Suppose 30,000 lbf are slacked off from...

## Tolerances On Dimensions

The following table shows the tolerance on manufacturing dimensions for API tubulars. The following problem shows by example the affect of tolerances on the strength of API casing. Compute the minimum body yield strength of 7 6.276 26 ppf N-80 casing. Nominal wall thickness, t Wall thickness tolerance Minimum wall thickness 0.362 1 - .125 Minimum OD - Wall thickness 6.9475 - 2 0.317 6.314 in Minimum Cross-sectional Area .7854 OD2 - ID2 Adjustment of API yield strength factor 0.9 Yield strength...

## Pressure Effect

As the pressure in the mud increases, the shear stress at a shear rate increases. The equation for pressure adjustment of viscometer readings shear stress is c Pressure constant which must be computed for Tp2 Shear stress or viscometer reading at a higher pressure Tpi Shear stress or viscometer reading at a lower EXAMPLE REYNOLD'S NUMBER AND PRESSURE LOSS Compute the expected viscometer readings for the temperature of 92 degrees F. The temperature for the first set of readings was 62 degrees F...

## Overburden [ Pressure

1T ' f1 11 ' i 1 r 1 ,J ImIIIIT The pressure of the fluid in the wellbore must surpass the unit weight of the overburden includes the rock and the fluid within its pores and the tensile strength of the rock in order to lift the overburden and create a fracture. wellbore pressure to create a horizontal fracture psi overburden stress psi unit tensile of rock being fractured psi

## The Gilligan

The gilligan is the easiest and fastest sidetrack method however, it can not be oriented in azimuth and the angle of build is not particularly predictable. The method calls for the placement of one joint of drillpipe below the BHA, a cross-over sub, and then the drill bit. One thousand to five thousand pounds are put on the drill bit for the purpose of buckling the drillpipe and making the bit drill. The canting of the bit by the buckling of the drillpipe causes the bit to build angle away from...

## Tangential Stress

Two formulae are available for computing the tangential torsional shear stress. The first uses the number of turns of the drillpipe while the second uses the torque applied to the drillpipe. and eliminating Tt from the two formulae relates Q and N G shear modulus of steel, 12 106 psi N number of turns in the free drillpipe rev Q torque applied to the drillpipe lb-ft polar moment of inertia, D4 - d4 inch4 The equation for axial shear stress which is associated with bending of the drillpipe is As...

## Perforating Procedure

A perforating gun consists of the gun which contains the jet charges and a collar locator tool. The collar locator tool detects the air gap in either casing connectors or tooljoints. After it is decided where the hole or holes are to be shot from logs, a nearby casing collar, which is easily identified by its proximity to collars on either side of it, the top shot in the perforating gun is raised never lowered to the pre-selected depth and fired. The distance to raise the CCL is equal to the...

## Mechanical Properties Of

The following are properties of BHA's which are prevalent throughout the literature of BHA's. Cross-sectional area A in2 Air weight Ws lbs ft Buoyed weighf'BW lbs ft Cross-sectional second moment of inertia I in4 polar moment of inertia J in4 steel has a density of 0.2832 lbs in3 or 65.45 ppg steel has modulus of elasticity E of 30E6 lbs in2 steel has modulus of shear G of 12E6 lbs in2

## Venting The Kick with engineer s method

During the venting of the kick, the casing pressure will drop, from its highest value to a pressure equal to the difference in the pressure across the length of the kill mud and the pressure across a similar length of kill mud, in a linear manner as the mud fills the space occupied by the kick . In our example the highest casing pressure value is 1,057 psig and the pressure difference is 29 psig. The volume of mud to pump to remove the kick from the hole volume of the annulus is Vm 600 .0836...

## Powerlaw Flow Model

T Farm rotary viscometer reading R Fann rotary viscometer speed For reference the laminar Newtonian equations are pressure loss for the length of pipe or annulus, L length of pipe or annulus ft fluid viscosity cps fluid velocity ft sec inside diameter of pipe inch The following steps illustrate the full, complete, no short cut powerlaw model procedure of Rabinowitsch, Metzner, Reed, Dodge, and Savins. 1. Make a logarithm-logarithm chart of the rotary viscometer data X rotary viscometer reading...

## Pocy

curvature of the build up section of the traverse Ex 27100ft linear section of the traverse Drawing line 14-target angle between the slant and the vertical Ex 25.74 point in the drill hole at the end of the slant and the top of the drop not on drawing curved section of the traverse between the slant and the hang not on drawing curvature of the drop off Ex 37100ft linear sections of the traverse below the drop off not on drawing angle between the hang down and the vertical not on drawing...

## Uses Of Horizontal Well

Horizontal wells are directional wells drilled with an inclination angle near 90 degrees. The purposes of drilling horizontal wells are not new. However, the application of solid state electronics in directional drilling at long last permits the fulfillment of those purposes. The primary purposes of horizontal wells are the following 1. Intersect many fractures in a hydrocarbon containing formation. Very popular in limestone and some shale formations. 2. Avoid drilling into water below or gas...

## Wall Force in Doglegs

If drill pipe is within a dogleg, the lateral force will be concentrated at the tool joint if the wall of the drillpipe does not contact the wall of the hole. This is the usual case. The dogleg concept is illustrated in the figure. The wall force created by drillpipe tension and a dogleg is computed with the equation WF wall force on a single tooljoint lbs T tension in the drillpipe at the dogleg lbs DLS dogleg severity of the dogleg deg ft LJ joint length of one drillpipe ft

## Pressure Gauge

Solids injectors inject hole-drying powders into the wellbore to dry weeping water zones or to reduce torque in a deep hole. The endless chain or belt type with pistons are most practical. Water Content of Air and Other Gases at Saturated Conditions after Deaton and Frost Water Content of Air and Other Gases at Saturated Conditions after Deaton and Frost The scrubber removes excess water in the air stream to assure that a minimum of moisture is circulated and to protect the booster in some...