Section 6
Liner Cementing Table of Contents Introduction................................................................................................................................................6-3 Topic Areas ................ .................. .................. .................. .................. .................. .................. ................ 6-3 Learning Objectives .................. ................. .................. .................. .................. .................. ................... . 6-3 Unit A: Types of Liners ................ .................. .................. .................. .................. .................. .................. . 6-3 Drilling Liners........................................................................................................................................6-3 Production Liners ................. .................. .................. .................. .................. .................. ................. ....... 6-4 Stub Liners ................ ................. .................. ................. .................. .................. .................. ................. ..6-4 .. 6-4 Scab Liners.............................................................................................................................................6-4 Quiz A: Types of Liners.........................................................................................................................6-5 Unit B: Setting Liners ................ .................. .................. .................. .................. .................. .................. .... 6-6 Preparing Liners .................. .................. ................. .................. .................. .................. ................... ....... 6-6 Making Up Liners ................ .................. ................. .................. .................. ................. ................... ....... 6-6 Running Liners.......................................................................................................................................6-7 Quiz B: Setting Liners............................................................................................................................6-7 Unit C: Cementing Liners..........................................................................................................................6-8 Single Stage Method .................. .................. .................. .................. .................. .................. ................. . 6-8 Delayed-Set Method...............................................................................................................................6-9 Quiz C: Cementing Liners......................................................................................................................6-9 Unit D: Liner Calculations.......................................................................................................................6-10 The Required Calculated Results .................. .................. .................. ................... .................. .............. 6-10 Well Parameters .................. .................. .................. .................. .................. .................. .................. ..... 6-10 Liner Cementing Job One.....................................................................................................................6-12 1 Cement Volume ................ ................. .................. ................. .................. ................. ................... ..... 6-13 2 Sacks of Cement ................. .................. ................. .................. ................. .................. .................. ...6-15 ... 6-15 3 Mixing Water Required ................. .................. .................. .................. ................. ................... ........ 6-15 4 Displacement Fluids Required ................. .................. .................. .................. .................. ................ 6-15 5 Top of Cement with Drillpipe In and Drillpipe Out .................. ................... .................. ................. 6-16 6 Pressure to Land the Plug ................ ................... .................. ................... .................. ................. ..... 6-17 Quiz D: Liner Calculations...................................................................................................................6-17 Answers to Unit Quizzes ................. .................. .................. .................. .................. .................. .............. 6-18
6•1
Cementing 1
Liner Cementing
Use for Section notes…
6•2
Cementing 1
Liner Cementing
Introduction In the past, it was common to have several strings of casing in a deep well. All these strings extended from the wellhead to different depths. However, another method is now used for varying well conditions. This time, and money, saving method involves the hanging of a casing string from the bottom of a cemented casing string. These hanging casing strings are called liners and they are used in almost every deep well completion.
C. Cementing Liners D. Liner Calculations
Learning Objectives Upon completion of this section, you should be familiar with
Topic Areas The section units are
•
The different types of liners
•
How liners are set
•
The different techniques of cementing liners
•
How to perform liner cementing calculations
•
isolates lost-circulation zones
•
isolates high-pressure zones
A. Types of Liners B. Setting Liners
Unit A: Types of Liners Four types of liners will be described briefly to begin this section: •
Drilling (or intermediate) liners
•
Production liners
•
Stub liners
•
Scab liners
Drilling Liners A drilling liner (sometimes called an intermediate liner) is a string of casing that is hung from another casing of a larger diameter, which has already been cemented downhole (Fig. 6.1). It is used above a producing zone to case off open holes so that deeper drilling may be performed. A drilling liner •
Figure 6.1 – Drilling and Production Liners.
helps control water or gas production
6•3
Cementing 1
Liner Cementing
Production Liners
ends and is used under the same conditions as a stub liner.
A production liner is a string of casing that is hung from a drilling liner or casing in the producing formation (Fig. 6.1). This type of liner is then cemented and perforated like any other completion string. It provides isolation and support when casing has been set above the production zone.
Both stub and scab liners can be set with part of their weight on the liner below or they may be hung uphole on existing casing (Fig. 6.2).
Stub Liners A stub liner (or tie back liner) is usually a short string of casing which provides an upward extension for a drilling liner. It is run when: •
•
•
casing above the drilling liner has been damaged in some way (by corrosion, etc.)
Figure 6.2 – A. Scab Liner and B. Stub Liner.
a liner is leaking greater resistance is needed for other reasons (abnormal pressure, etc.).
Scab Liners A scab liner is unusual in that it is often not cemented once it has been run downhole and is therefore retrievable. It has a packoff on both
6•4
Cementing 1
Liner Cementing
Quiz A: Types of Liners Fill in the blanks with one or more words to check your progress in this section. 1. A drilling liner is used above a __________________________________________ zone to case off open holes so that _________________________________ may be performed. 2. A drilling liner helps to control __________________ production and to isolate ___________________ and ______________________ zones. 3. A production liner is hung in the producing formation. It is cemented and ___________________ like any completion string. 4. The main difference between stub and scab liners is that a scab liner is ________________________. 5. Stub and scab liners are short liners that are used when casing above a drilling liner has been ________________. They can also be used when a liner is _______________________ or when greater ________________________ is needed because of high pressure or other reasons. 6. Stub and scab liners can be hung uphole on existing casing or they can be set with part of their weight on the __________________________. Now, look up the suggested answers in the Answer Key at the back of the section.
6•5
Cementing 1
Liner Cementing
Unit B: Setting Liners relatively small. If the liner is not centralized, the result may be bridging or channeling. A uniform cement sheath has not been formed around the liner, therefore no zonal isolation. Slim-hole centralizers are usually used when running liners because of the small annular space. Downhole equipment considerations are the same as if the joints would be run to the surface.
When setting liners, it is important to be familiar with these three areas: •
Preparing liners
•
Making up liners
•
Running liners
Preparing Liners
Drill pipe and a setting tool are used to run a liner (Fig. 6.3). The setting tool connects the drill pipe to the liner, forms a pressure-tight seal with the liner, and holds the liner-wiper plug.
Before setting a liner, the entire length of hole to be lined must be drilled. It is very important to prepare the liner before lowering it into the wellbore; the mill finish must be removed so that cement can form a better bond with the liner. This usually is done by sandblasting or weathering the liner. The hole must be well-conditioned to set a liner because of the small annular space. To condition the mud system, circulate at least enough drilling fluid to displace the annular volume twice. Decisions must be made about how much overlap there should be between the casing and the liner. The amount of overlap varies between 50 and 500 feet. For example, if higher pressure zones are penetrated, there should be more overlap than in lower pressure zones.
Making Up Liners The liner is made up like any casing string. While suspended in the rotary table, it is made up joint by joint. A float shoe is made up on the first joint and a float collar is attached on the second or third joint to provide a seat for the liner-wiper plug. Sometimes a landing collar is also made up one joint above the float collar (Fig. 6.3). In this case, the landing collar provides a seat for the plug.
Figure 6.3 – Typical deep well liner assembly.
Centralizers are important in liner jobs because the clearance between the liner and casing is
6•6
Cementing 1
Liner Cementing
Running Liners
•
Running speeds should be slow to reduce the ram effect. The liner can cause added pressure on the formation, resulting in breakdown or lost circulation. Speeds of 2 to 3 minutes per stand (90 ft drill pipe) are usually allowed for cased holes.
Hydraulic equipment is used less often. However, it is less likely to set accidentally and is preferred in crooked holes. Once the liner is set, the drill pipe should be temporarily raised a few feet. The weight indicator should be checked to be sure that the liner has actually been released.
After a liner has been lowered into the well, the slips are activated so that the liner hangers are wedged against the casing. Liner hangers are set in one of two ways: •
Hydraulic- hydraulic pressure applied to the setting string activates the slips.
Spacer fluid is then pumped down-hole so that a good cement bond can be obtained. The seal formed by a good cement job is especially important at the shoe and at the top of the liner.
Mechanical- slips are activated by rotating and reciprocating the drill pipe
Quiz B: Setting Liners Fill in the blanks with one or more words to check your progress in this section. 1. One step in the preparation of a liner is to ______________ the mill finish. This is usually accomplished by ____________________________________________. 2. The amount of overlap between the casing and the liner is usually between _________ and _________ feet. 3. Because of the small clearance between a casing and a liner, it is very important to make sure the liner is __________________________. 4. The ________________ collar provides a seat for the liner-wiper plug. 5. The setting tool connects the ___________________ to the liner and forms a ____________________________________________ with the liner. 6. After the liner has been set, _________________________________ is pumped down hole. Now, look up the suggested answers in the Answer Key at the back of the section.
6•7
Cementing 1
Liner Cementing
Unit C: Cementing Liners Two techniques for cementing liners will be discussed next: •
Single stage method
•
Delayed-set method
Regardless of the method chosen, batch mixing is generally preferred because of the complexities in obtaining the best slurry composition for a particular job. In designing the composition of cement slurry, the following factors must be considered: •
•
Temperature of the well Pressure caused by small annular clearance (possibility of lost circulation)
•
Formation fluids
•
Pump or thickening time
•
Strength or stability of the cement
Figure 6.4 – Single Stage Method.
Single Stage Method 10 to 30% more than the caliper-calculated volume of cement is pumped when using the single stage method of cementing liners. This amount of cement is circulated down the drill pipe (behind the spacer fluid). It travels out the shoe and up the outside of the liner (Fig. 6.4). The pump-down plug is released and pumped down with displacement fluid. It mates with the liner-wiper plug and its pins are sheared off. Both continue downward until they seat and seal on the float or landing collar.
Bottom plugs are generally not run in liner cementing; therefore, as the two plugs descend, they wipe mud off the liner. This mud, trapped between the shoe and the collar, should not go into the annulus to contaminate the cement. The drill pipe and setting tool are then pulled out of the hole. It is risky to reverse out excess cement at this point because this process would exert extra pressure on the annulus. The extra pressure could break down the formation and cause lost circulation. This would leave the overlap area unprotected. Instead, the cement is drilled out after it has set, which should result in a good bond in the liner-casing overlap.
6•8
Cementing 1
Liner Cementing
Delayed-Set Method The delayed-set method is used in certain geographical locations when a relatively short liner is called for in wells with low fluid levels. It is carried out by pumping delayed-set cement down the drill pipe. The drill pipe is then pulled out and the liner and attachments are lowered into the hole (Fig. 6.5). The closed float collar valve in the liner forces the cement up the annulus. This increases the chances for obtaining a more uniform cement sheath around the liner. However, since delayed-set cement is used, WOC time is greater-sometimes two days or more. After any of these procedures have been completed, the liner's seal is tested. The casing is then cleaned and, if necessary, the cement is drilled out so that the remainder of necessary completion operations can take place.
Figure 6.5 – Delayed-set Method of cementing liner.
Quiz C: Cementing Liners Fill in the blanks with one or more words to check your progress in this section. 1. ________________ % more cement than the caliper calculated volume is used with the single-stage method of cementing liners. 2. The path that the cement takes is down the ________________ and then up the ______________ in the single-stage method. 3. It is risky to reverse out cement when the workstring is pulled in the single-stage method because this would ______________________________________. 4. The delayed-set method differs from the single-stage method because the liner is lowered into the hole ____________ the cement is pumped down. 5. When delayed-set cement is used, the WOC may be increased by ___________________________. Now, look up the suggested answers in the Answer Key at the back of the section.
6•9
Cementing 1
Liner Cementing
Unit D: Liner Calculations Before a liner job is started, calculations must be performed. These calculations are based on known information and on figures obtained from your Halliburton Cementing Tables (the Red Book ).
6. Required pressure to land the plug, being the differential pressure required to pump the plug to the top of the shoe track.
Well Parameters
In this unit, you will go through the calculations necessary for a liner cementing job. You will learn how to calculate answers to the following questions: •
•
•
•
•
Following are the well parameters that you must have to perform the above calculations: A. Liner Size
Where is the top of the cement when the drill pipe is out?
B. Liner Top
What pressure is needed to land the plug?
C. Well Fluid
How much displacement fluid is needed to land the plug?
D. Hole Size
What is the force on the plug when it has a given psi above the pressure to land the plug on it?
F. Shoe Track Length
What is the hydrostatic pressure at a given depth after the plug lands?
H. Excess Volume Required (percent)
E. Liner Total Depth
G. Required Cement (on top of liner)
The Required Calculated Results
I.
Size of Previous Casing
J.
Depth of Previous Casing
K. Drill pipe size, weight, thread
The following must be calculated for liner cementing: 1. Volume of cement required to fill the required footage of the shoe rack, annulus, lap, and cap. 2. Amount of cement, converting the required volume of cement into sacks. 3. Amount of mixing water for the slurry. 4. Amount of displacement fluid for (a) drill pipe volume to top of liner and (b) liner casing volume to top of shoe track. 5. Top of cement, both with drill pipe in and top of cement with drill pipe out.
6 • 10
Cementing 1
Liner Cementing
Liner Cementing Calculations 6 critical calculations that need to be made with every liner casing job
K 4A
Cement Volume—The volume of cement required to fill the required footage of the shoe rack, annulus, lap and cap.
I 1
C G B H
5 1D
1A
Shoe Track Volume
1B
Open Hole Volume
1C
Liner Lap Volume
1D
Liner Cap Volume
2
Sacks of Cement—Converting the required volume of cement into sacks.
3
Mixing water for required slurries. Displacement fluid required:
1C
4
4A
Drill pipe volume to top of liner.
4B
Liner casing volume to top of shoe track.
J
5
Top of Cement with drill pipe in and top of cement with drill pipe out.
D
6
Pressure to Land the Plug—Differential pressure required to pump the plug to the top of the shoe track
Well Parameters
4B A
1B
F
A
Liner Size
B
Liner Top
C
Well Fluid
D
Hole Size
E
Liner Total Depth
F
Shoe Track Length
G
Required Cement (on top of liner)
H
Excess Volume Required (percent)
I
Size of Previous Casing
J
Depth of Previous Casing
K
Drill pipe size, weight, thread
The next part of this section presents an example liner job and shows the calculations.
1A
E
6 • 11
Cementing 1
Liner Cementing
Liner Cementing Job One In previous exercises, we calculated volumes of cement based on perfect hole volumes and excess volume factors typical for each job. Iin the following liner job, we will be supplied a specific spacer and slurry volume, just as you would with a call-sheet before mobilizing for a job. From the known volume of cement and spacer we will then perform the six major liner calculations.
4 1/2 in., 16.6 lb/ft
For this example, the liner job consists of a weighted spacer and slurry with known volumes of each.
9 5/8 in, 47 lb/ft
11,600 ft
11,930 ft
Well Parameters Item
Description
Data
A
Liner Size
7 in, 29 lb/ft, N-80
B
Liner Top
11, 600 ft
C
Well Fluid
12.4 lb/gal
D
Hole Size
8 ½ in.
E
Liner Total Depth
F
Shoe Track Length
G
Required Cement (on top of liner)
H
Excess Volume Required (percent)
I
Size of Previous Casing
J
Depth of Previous Casing
K
Drill pipe size, weight, thread
8 1/2 in. hole
12,925 ft 81 ft 300 ft cap 10% 9 5/8 in, 47 lb/ft, N-80 11,930 ft
81 ft
4.5 in, 16.6 lb/ft
12,925 ft Total Depth
Given (from Call-Sheet)
Figure 6.6 – Schematic of example well for exercise.
Pump 40 bbl of 13.5 lb/gal Dual Spacer, followed by 225 sacks of Premium Class G Cement containing 35% SSA-1, 0.5% CFR-3, + 0.1% HR-5. Displace with 12.4 lb/gal WB drilling mud.
On the following page is the worksheet used for determining slurry volumes.
6 • 12
Cementing 1
Liner Cementing
start from the shoe track and work your way up the annulus to solve for height of cement with the drill pipe at the liner hanger.
Worksheet for Slurry Volumes Worksheet for Slurry Weight and Volume Calculations Liner Job One API Cement Weight = 94 lb/sack
Volume of Cement Delivered 3
225 sk × 1.57 ft /sk
1 sack = 1 cubic foot Material Name
Material (lb)
Class G Cement
Factor (gal/lb)
Absolute Mixing Volume Water (gal) Required (gal)
94 ×
0.0382 =
3.59080
5.00
35% SSA-1 (silica flour)
32.9 ×
0.0453 =
1.49037
1.61
0.5% CFR-3 (dispersant)
0.47 ×
0.0938 =
0.04409
0.094 ×
0.075 =
0.00705
0.1% HR-5 (retarder) Water
1A 1B
Shoe Track Volume 3 81 ft × 0.2085 ft /ft
Totals 182.525
=
16.89 ft
3
3
Note: This volume was based on perfect hole + 10% excess (additional volume). We will calculate perfect hole, knowing that this will increase the top of cement and give us worst case for pressure to land the plug. TD Liner: Depth Previous Casing:
3
8.33 =
353.25 ft
Open Hole Annular Volume
995 ft × 0.1268 ft /ft 55.0613 ×
=
12,925 ft - 11,930 ft 995 ft of open hole =
126.17 ft
3
6.61000 11.74231
6.61
Total mixing water must be entered under absolute gallons before totaling. Find the weight of the mixed cement by using this formula: Total Pounds ÷ Total Absolute gallons = lb/gal
1D
1D
1C
1C
1B
1B
Find the cement yield in cubic feet per sack by using this formula: 3
3
Total Absolute gal ÷ 7.4805 gal/ft (constant) = ft /sk The mixing water per sack is the sum of the gallons in the far right column Cement Density
182.525 ÷
11.7423 =
15.5
lb/gal
Cement Yield
11.7423 ÷
7.4805 =
1.57
ft /sk
6.61
gal/sk
Mixing Water Required
3
From the well parameters and the data from this worksheet, we can now calculate the six requirements.
1 Cement Volume Cement Volume is an extremely critical calculation in a liner situation (as with all jobs). In particular with liners, if you underestimate cement volume, you could leave the previous casing shoe unprotected. Therefore, it is your responsibility to know the volume of cement delivered and to ensure that the volume of cement is sufficient to execute the job.
1A
Working from the known volume of cement, 225 sk, you must solve for the height of cement above the liner. To accomplish this you must
Figure 6.7 – Schematic for cement volume.
6 • 13
Cementing 1
Liner Cementing
1C - Liner Lap Volume (Annular Volume between Casings)
Looking in Section 221, Table 221-D, we find that the volume factor is not printed for 9 5/8 in. casing.
This is the volume between the existing 9 5/8 in. intermediate casing and the 7 in. liner, commonly referred to as the “Liner Lap.” This volume is calculated as “Perfect Hole” with no washout or excess (because we are working with pipe inside pipe).
There is an easy way to calculate this factor. All you need to know is 1. Drillpipe O.D.
4.5 in
2. Casing I.D. we look up the I.D. in section 210, Table 214, page 23 and find the I.D. for 9 5/8 in., 47 lb/ft, casing is 8.681 in.
Lap Footage (Section 221, Page 113):
The formula for calculating the volume factor is found in section 240, page 10.
9 5/8 in. pipe depth: 11,930 ft 7 in. top of liner: -11,600 ft 330 ft of Lap
Linear feet per Cubic Feet = 183.35 D2 - nd2
330 ft × 0.1438 ft 3/ft = 47.45 ft 3
where:
1D - Liner Cap Volume (Annular Volume Between Drill Pipe and Casing)
D = Diameter of hole, inches (or I.D. casing) d = Outside Diameter of tubing, inches n = number of tubing strings
This is the volume above the liner hanger inside the intermediate casing commonly referred to as Liner Cap Cement. This volume will reach its maximum height when the plug lands. This will give you the maximum differential pressure (pressure to land plug). As you pull drill pipe, the height will decrease until the drill pipe is pulled above the slurry.
(in our case, we are calculating the annulus between 9 5/8 in. casing and 4.5 in. drill pipe)
Therefore, we will make two calculations:
Therefore, for every cubic foot of slurry in the annulus, we fill up 3.33 feet of annular length.
Applying the Formula:
183.35 8.6812
Shoe Track Volume:
3
- 16.89 ft
Annular Hole Volume: (perfect hole):
- 126.17 ft3
Liner Lap Volume:
- 47.45 ft 3
Resulting Cap Volume:
162.74 ft 3
75.36 − 20.25
=
183.55 55.11
And
(b) Height of Cement with drillpipe pulled above the Cement Column. 353.25 ft 3
4.5 2
183.35 =3.33 ft/ft3
(a) Height of Cement with drillpipe in Liner Hanger
Total Cement Volume:
−
=
162.74 ft3 of slurry × 3.33 ft/ft 3 = 541.92 ft annular fill (drillpipe in) Likewise, this is a good time to calculate the height of spacer. We are pumping 40 bbl of spacer. We calculated the annular volume factor in ft/ft3. Therefore, all we need to do is convert bbl to cubic feet and multiply by the annular fill factor. (Section 240, Page 85) 40 bbl × 5.6146 ft 3/bbl = 224.58 ft 3 spacer 224.58 ft3 × 3.33 ft/ft 3 = 747.85 ft spacer (DP in)
Height of Cement (with drillpipe in)
Now, knowing the top of the liner is at 11,600 ft, the length of the cement on top of the liner is 541.92 ft (DP in); the length of spacer on top of the cement is 747.85 ft (DP in), therefore it is easy to calculate the top of each fluid.
We have calculated that 162.74 ft 3 of cement will remain above the Liner Top. We should be able to multiply by the ft/ft 3 volume factor of the 4.5 in drill pipe × 9 5/8 in. intermediate casing.
6 • 14
Cementing 1
Liner Cementing
Height of Cement (with drillpipe out) This calculation is a lot simpler in that we are only concerned with the 9 5/8 in, 47 lb/ft capacity. Looking up the capacity value we calculate the following…
4A
162.74 ft3 × 2.433 ft/ft 3 = 395.95 ft This means that after pulling drill pipe above the cement on top of the liner, the height of the cement column will be 395.95 ft above the liner top so yes, we have enough cement to complete this job.
2 Sacks of Cement In this job, we were given 225 sacks of cement. But, it is fairly easy to see that in future job calculations (to predict how much cement to order) you must calculate 4 different volumes of cement in a liner job (Figure 6.7),
4B
1A - Shoe Track Volume 1B - Open Hole Annular Volume (Plus Excess Cement) 1C - Liner Lap Volume 1D - Liner Cap Volume
3 Mixing Water Required We know the number of sacks of cement is 225. We also know the water requirement (from callsheet or calculations) is 6.61 gal/sk.
Figure 6.8 – Schematic of data needed for determining amount of displacement fluid required.
225 sk × 6.61 gal/sk = 1487.25 gal ÷ 42 gal/bbl = 35.41 bbl
Calculating the amount of displacement fluid is critical for a number of reasons. Naturally, we want to land the plug on the top of the shoe track. But other considerations also need to be understood:
(Have 50 bbl of clean, fresh water on hand)
4 Displacement Fluids Required
1. We need to know any diameter changes in either string and their lengths.
For this calculation, we need to recognize we are dealing with at least two different pipe diameters, which are explained further below.
2. We need to pay close attention to the transition point between drill pipe and liner casing. Many times a 2-stage plug is run which wipes the drill pipe of cement and
6 • 15
Cementing 1
Liner Cementing
then latches into a larger plug in the liner hanger. If we slow our pump rate down and watch closely for a pressure increase, we will then have an accurate volume up to that point in the job. Then we can focus on displacing the liner casing capacity to the top of the shoe track.
TOC 10,310.23 ft
TOC 11,058.08 ft
4A - Drillpipe Volume 4 ½ in. 16.6 lb/ft Top of Liner at 11,600 ft (Section 210, Table 212B, Page 9): 11,600 ft × 0.01422 bbl/ft = 164.95 bbl
4B - Liner Casing Volume Total Depth Shoe Length
12,925 ft 81 ft 12,844 ft Top of Shoe
12,844 ft - 11,600 ft (top of liner) = 1244 ft of 7 in., 29 lb/ft liner (Section 210, Table 214, Page 21) 1244 ft × 0.0371 bbl/ft = 46.15 bbl Therefore, we will pump: 164.95 bbl Drillpipe Capacity + 46.15 bbl Liner Capacity = 211.1 bbl total displacement 12,925 ft
Figure 6.9 – Schematic showing top of cement (drillpipe in).
5 Top of Cement with Drillpipe In and Drillpipe Out From 1D we found the length of cement above the liner hanger was 541.92 ft (drillpipe in).
Liner Displacement Fluids Note
11,600 Top of Liner -541.92 ft Length of Cement above liner = 11,058.08 top of cement with drillpipe in
Liners are usually displaced with drilling mud (instead of water). This is done to prevent a large pressure differential at the liner hanger tool and at surface.
Also from 1D: We found that the length of cement above the liner hanger was 363.1 ft. (drillpipe out).
Operationally speaking, we need to pay close attention to mud delivery rate, mud volume on location as well as air entrainment (which can cause error in displacement volumes). This will be discussed at length in Cementing II.
11,600 ft Liner Top –395.95 ft Length of cement above liner = 11,204.05 ft T.O.C. drillpipe out
6 • 16
Cementing 1
Liner Cementing
Hydrostatic Pressure (Inside)
6 Pressure to Land the Plug Refer to Section 240, Page 18 to arrive at psi/ft for lb/gal figures. Hydraulic Pressure (Outside) 15.5 lb/gal Cement
12,925 ft – 11,058.08 ft = 1866.92 ft
x
0.8052 psi/ft
=
1503 psi
13.5 lb/gal Spacer
747.85 ft
x
0.7013 psi/ft
=
524 psi
12.4 lb/gal Mud
10,310.23 ft
x
0.6442 psi/ft
=
6642 psi
Total
12,925 ft
15.5 lb/gal Cement
81 ft
x
0.8052 psi/ft
=
65 psi
12.4 lb/gal Mud
12,844 ft
x
0.6442 psi/ft
=
8274 psi
Total
12,925 ft
8339 psi
8669 psi – 8339 psi = 330 psi to land the plug
8669 psi
Quiz D: Liner Calculations Fill in the blanks with one or more words to check your progress in this section. 1. What are the six critical calculation required for each liner cementing job? •
__________________________________________________________
•
__________________________________________________________
•
__________________________________________________________
•
__________________________________________________________
•
__________________________________________________________
•
__________________________________________________________
2. With liners, if you underestimate _______________________, you could leave the previous casing shoe unprotected. 3. Liners are usually displaced with _______________________________ to prevent a large pressure differential at the liner hanger tool and at the surface. Now, look up the suggested answers in the Answer Key at the back of the section.
6 • 17
Cementing 1
Liner Cementing
Answers to Unit Quizzes Items from Unit A Quiz
Refer to Page
Items from Unit C Quiz
Refer to Page
1.
producing, deeper drilling
6-3
1.
2.
water or gas, lost-circulation, high-pressure
6-3
2. drill pipe, outside of the liner
6-9
3.
6-9
3.
perforated
6-4
exert extra pressure on the annulus
4.
retrievable
6-4
4.
after
6-10
5.
damaged, leaking, resistance
6-4
5.
two days or more
6-10
6.
liner below
6-4 Items from Unit D Quiz
Refer to Page
Items from Unit B Quiz
Refer to Page
1.
remove, sandblasting or weathering
6-6
2.
50, 500
6-6
3.
centralized
6-6
4.
float
6-6
5.
drill pipe, pressure-tight seal
6-6
6.
spacer fluid
6-7
6 • 18
10 to 30
6-9
1.
Volume of cement Amount of cement in sacks Amount of mixing water Amount of displacement fluid Top of cement Required pressure to land plug
6-10
2.
cement volume
6-13
3.
drilling mud
6-16
Cementing 1
