JET Manual 08
Cement Heads and
Casing Hardware
JET Manual 08 Cement Heads and Casing Hardware
InTouch Content ID# 4127832
Version: 1.1
Release Date: July 31, 2006
Owner: Well Services Training & Development, IPC
Schlumberger private
Document Control
Revision History
Rev. Effective Date Description Prepared by
Copyright © 2006 Schlumberger, Unpublished Work. All rights reserved.
This work contains the confidential and proprietary trade secrets of Schlumberger and may not be copied or stored in an information retrieval system, transferred, used, distributed, translated, or retransmitted in any form or by any means, electronic or mechanical, in whole or in part, without the express written permission of the copyright owner.
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“Schlumberger,” the Schlumberger logotype, and other words or symbols used to identify the products and services described herein are either trademarks, trade names, or service marks of Schlumberger and its licensors, or are the property of their respective owners. These marks may not be copied, imitated or used, in whole or in part, without the express prior written permission of Schlumberger. In addition, covers, page headers, custom graphics, icons, and other design elements may be service marks, trademarks, and/or trade dress of Schlumberger, and may not be copied, imitated, or used, in whole or in part, without the express prior written permission of Schlumberger. A complete list of Schlumberger marks may be viewed at the Schlumberger Oilfield Services Marks page: http://www.hub.slb.com/index.cfm?id=id32083
An asterisk (*) is used throughout this document to designate a mark of Schlumberger. Other company, product, and service names are the properties of their respective owners.
Table of Contents
1.0 Introduction
7
1.1 Learning objectives
7
1.2 Safety warnings
7
2.0 Cementing Overview
9
2.1 Preparing the casing
10
2.2 Pumping the cement slurry
11
2.3 Displacement
12
2.4 End of job
13
3.0 Cementing Techniques
15
3.1 Primary cementing
15
3.1.1 Single-stage cementing
15
3.1.2 Two-stage cementing
15
3.1.3 Stab-in cementing
17
3.1.4 Liner cementing
18
3.2 Plug cementing
19
3.3 Remedial cementing
19
4.0 Plugs
21
4.1 Plug functions
21
4.1.1 Botom plugs
21
4.1.2 Top wiper plug
22
4.3 Nonrotating and rotating wiper plugs
22
4.4 Wiper plug manufacturers
23
4.5 Cementing wiper plug sequence
24
5.0 Overview of Cement Heads
27
5.1 Conventional cement heads
27
5.1.1 Conventional cement heads
29
5.2 Cement head pressure ratings
29
5.2.1 IRI fabricated cement head (305 and 306 series)
29
5.2.2 IRI integral cement head (307 and 308 series)
30
5.3 Single-plug cement head
30
5.4 Double-plug cement head
30
6.0 Cement Head Components
33
6.2 Caps
34
6.3 Pull pin assembly
34
6.4 Tattletale
35
6.5 Casing nipple
35
6.6 Bull plug
35
6.7 Quick-connect coupling
36
7.0 Cement Head Job Execution
43
7.1 Cement head prejob checklist
43
7.1.1 General job inspection procedure for cement heads
45
7.1.2 Safety
48
7.1.3 Before attaching the cement head
48
7.1.4 Loading the wiper plugs
48
7.1.5 Setting the tattletale
50
7.1.6 Connecting the cement head
50
7.1.7 Pressure testing
52
7.1.8 Excessive pressure testing
52
7.2 Single-stage job
53
7.2.1 Dropping plugs in a single-stage job
53
7.2.2 Troubleshooting
54
7.3 Two-stage job
56
7.4 Non-standard cement plug
57
7.4.1 At district
57
7.4.2 On location
57
7.5 Postjob
57
8.0 Maintenance and Inspections
59
8.1 12-month inspection
59
8.1.1 Cap and O-ring inspection guideline
61
8.1.2 O-ring inspection
62
8.1.3 Inside cement head inspection
62
8.1.4 Pull pin inspection
62
8.1.5 Manifold valves
64
8.1.6 Maintenance bulletins
64
9.0 Casing Adapters
65
9.1 Casing threads
65
9.2 Crossovers
66
9.3 Quick coupler
66
9.4 Fast-latch couplers (FLC)
67
9.4.1 Fast-latch coupler
67
iv | Table of Contents9.4.2 Operation
68
9.4.3 Adjustment operation
69
9.4.4 Rig-down
71
9.4.5 Pressure test
73
9.4.6 Preventive maintenance
73
9.4.7 Disassembly
74
9.4.8 Assembly
75
9.4.9 Troubleshooting
75
9.5 Circulating swages
75
10.0 Hardware
77
10.1 Shoes
77
10.1.1 Guide shoes
77
10.2 Float collars
78
10.3 Two-stage cementing collars
79
10.4 External casing packers (ECP)
80
10.5 Baskets and centralizers
80
10.6 Scratchers and collars
83
10.7 Liner hardware
83
10.8 Squeeze and top-out cementing equipment
84
10.9 Squeeze manifold
85
10.10 Packer
86
11.0 References
87
12.0 Appendix
91
12.1 Rig-up from ground to rig floor and to the cement head
91
12.2 Cement head tables
92
12.3 Prejob check-list
93
12.4 Rig-up and rig-down checklist
94
12.4.1 Prejob checks
94
12.4.2 Installation procedure
94
12.4.3 Pressure testing
94
12.4.4 Launching the bottom plug
95
12.4.5 Launching the top plug
95
12.4.6 Launching two-stage plugs
95
12.4.7 Postjob
95
12.4.8 Additional information/precautions
96
In this manual you will be introduced to equipment related to the casing in the well, including peripheral equipment, such as cement heads, plugs, casing hardware, squeeze
manifolds, casing couplers and adapters, and circulating swedges.
The manual will
name the types of equipment, and explain their functions
explain operational procedures for the different equipment
explain the maintenance procedures explain the pre- and postjob checks required
1.1 Learning objectives
Upon completion of this training, you will be able to do the following:
Describe the types of cement heads used by Schlumberger
Describe the applications for each type of cement head
Name the components of the conventional cement head, as well as any associated equipment
Name the options for connecting the cement head to the casing
Describe the different types of threads generally found in casings and tubings Explain the prejob checklist for a conventional cement head
Describe the STEM I process for a cement head and manifold
• • • • • • • • • • •
Describe the pressure test interval and procedure for cement heads and manifolds Describe what MAWP (maximum allowable pressure) is and how it applies to the
cement head
Explain the correct procedure for dropping the top and bottom plugs
Explain how the pressure equalizes inside the loaded cement head
Explain what a tattletale is and why it is used
Explain what “dropping the plug on the fly” means
Identify the different kinds of casing hardware available and their uses
1.2 Safety warnings
Proper supervision is required during hands-on training and normal operatihands-on. Request assistance from your supervisor if you are unfamiliar or uncomfortable with the operation. Ensure that all safety devices are in place and operational before using the cement head. When operating the cement head on location, follow the procedures in Well Services Safety Standard (WSSS) 5: Pressure Pumping and Location Safety, InTouch Content ID# 3313681.
• • • • • • •
1.0 Introduction
8 | Introduction
Cementing is the process of hydraulically sealing the casing within the wellbore prior to perforation and hydrocarbon extraction. The annulus (the space between the casing and the formation) is filled with cement by pumping liquid cement slurry down through the casing and forcing it back up the annulus surrounding
Figure 2-1. Preparing the Casing and Mud
the casing. Wiper plugs are dropped ahead of and behind the slurry to keep it separate from preflushes (washer or spacer) pumped in front of the cement slurry, and the displacement fluid (mud or drilling fluid) pumped behind.
10 | Cementing Overview
Cementing is performed for the following main reasons:
to provide complete isolation of zones (hydraulic bond)
to support the casing (shear bond) to protect the casing string.
2.1 Preparing the casing
First, a drilling mud (also referred to as drilling fluid) is circulated down through the casing to
• • •
condition and clean the well. A pressure test checks that there are no leaks in the lines that connect the pumping unit to the well.
Then a chemical wash and/or a spacer are pumped in. The chemical wash is a fluid that helps thin and disperse the drilling mud ahead of the cement slurry.
The spacer is a weighted fluid with controlled rheological properties designed to keep cement slurry and mud separate
Next, a bottom plug, also called a wiper plug, is dropped from the cement head. This bottom plug cleans (wipes) the sides of the casing as it descends and provides a barrier between the mud and the cement slurry, which is pumped next.
2.2 Pumping the cement slurry
Once the bottom wiper plug is released, cement slurry is pumped from the cement unit and into the casing through the cement head which is
mounted on the top of the casing. The cement head is a pressure-rated container which holds the cement wiper plug(s) and allows their controlled release in a predetermined sequence.
In the case of continuous mixing, mixing while pumping can continue according to the requirements of the job. The cement head is a container mounted on the casing. It is attached to the cementing unit and allows for the
release of fluids and plugs in a predetermined sequence.
12 | Cementing Overview
The cement slurry pushes the wash and/or spacer and bottom plug ahead of it into the casing. When the bottom plug reaches the float collar, the plug's diaphgram ruptures and the wash, spacer, and slurry can flow to the casing shoe.
2.3 Displacement
Once mixing and pumping of the designed cement slurry or slurries is completed, the top wiper plug is released from the cement head.
Figure 2-4. End of Job
The top plug separates and protects the slurry against contaminants from the displacement fluid that will be pumped. The displacement fluid, typically drilling mud, pushes the top plug and slurry down into the casing. The slurry is forced out of the bottom of the casing and up into the annulus.
When the top plug reaches the bottom plug it is seald or "bumped" with the bottom plug by a presssure increase. When there is a
pressure increase indicated at the surface, the displacement is complete.
2.4 End of job
At the end of the job, it is normal for some displacement fluid to return through the treating lines, when opening the valves on the cementing unit. However, if the returns are greater than 3 to 5 barrels, it could be an indicator that the float collar is malfunctioning. The float collar contains a check valve
to prevent flowback up the casing. If it
malfunctions, slurry can push the plugs up into the casing as a result of a U-tubing effect. When the cement slurry hardens in the
annulus, it forms a barrier between the casing and the formation, isolating the casing from the formation fluids. This completes the cementing job.
14 | Cementing Overview
There are three main types of cementing applications, which can be differentiated from one another by their objectives. These are
primary cementing plug cementing remedial cementing.
A summary of cementing techniques is provided in this chapter. Please refer to the InTouch and the Well Services Training and Development web page for more details.
3.1 Primary cementing
Primary cementing is the placement of cement slurry in the annulus between the casing and the wellbore. The four major techniques of primary cementing are
single-stage two-stage stab-in liner.
3.1.1 Single-stage cementing
In single-stage cementing, cement slurry is placed in the annulus in one stage. This technique uses two plugs to prevent the intermixing of cement with other fluids used in the operation.
3.1.2 Two-stage cementing
Two-stage cementing refers to the placement of slurry around a lower and an upper portion of a casing string. • • • • • • •
The main pupose of two-stage cementing is to isolate two problem zones within one open hole section.
Two-stage cementing may be performed as one operation or two, depending on specific circumstances at the well.
The process for the first stage in two-stage cementing is as follows:
Circulate mud Pressure test
Pump washer and spacer Pump slurry
Drop first-stage plug
Bleed-off and check returns. 1. 2. 3. 4. 5. 6.
3.0 Cementing Techniques
16 | Cementing Techniques
Figure 3-1. Two-Stage Components
After the first-stage is completed, an opening bomb is dropped. This bomb opens the ports of the two-stage collar, a device that allows the opening of flow to the second stage of the job. The process for the second stage in two-stage cementing is as follows:
Drop opening bomb Establish circulation 1.
2.
Pump washer Pump slurry
Drop a closing plug similar to the top plug
Begin displacement
Bleed off and check returns. 3.
4. 5. 6. 7.
3.1.3 Stab-in cementing
Stab-in cementing is performed through drillpipe.
Figure 3-2. Stab-In Cementing Components
The pupose is to prevent problems associated with cementing large casing, such as.
contamination and channeling inside the casing.
Stab-in cementing is used for large casing sizes (generally bigger than 13 3/8 in) and at depths up to 3,000 ft.
Two additional advantages are that it reduces excess cement and can reduce job time (by reducing displacement volume.
The procedures for this technique are Mud circulation
Pressure testing
Mixing and pumping slurry 1.
2. 3.
18 | Cementing Techniques
Displacement
Releasing the stinger to remove the drillpipe from the inside of the casing.
3.1.4 Liner cementing
A liner is a string of casing that does not extend to the top of the wellbore. The liner is attached to casing by a liner hanger.
Figure 3-3. Liner Components
4. 5.
Liners also
cover corroded or damaged casing
cover lost circulation zones, shales, plastic formations, and salt zones
reduce the weight of the casing string. The liner cementing process consists of
mud circulation pressure testing • • • 1. 2.
pumping washer pumping slurry dropping the dart displacement bleeding off
releasing the setting tool from the packer
reverse circulation.
3.2 Plug cementing
Plug cementing is the placement of a relatively small volume of slurry anywhere in the
wellbore.
3.3 Remedial cementing
Remedial cementing is the process of forcing slurry under pressure through holes or splits in the casing or wellbore annular space. Remedial cementing is often referred to as squeeze cementing. 3. 4. 5. 6. 7. 8. 9.
Figure 3-4. Plug Cementing
The objectives of remedial cementing include the following:
Repair improper zonal isolation. Raise the top of the cement. Plug perforations.
Repair corroded casing.
This remedial work is performed with some of the tools described in this manual.
• • • •
20 | Cementing Techniques
4.1 Plug functions
Plugs have the following functions:
separate fluids and prevent contamination clean inner casing wall
provide surface indication when displacement is complete.
Cementing plugs are semi-rigid barriers used to separate cement from drilling fluids, wipe the casing, and indicate when cement placement is complete. Both top and bottom plugs are constructed of various types of elastomers, including natural rubber, polyurethane, nitrile, etc., molded over drillable aluminum, plastic, or wooden cores. Although similar in external appearance, top and bottom plugs differ considerably in internal design and operation. Top and bottom plugs are recommended for every primary cementing job, when possible. The bottom plug minimizes contamination of the cement as it is pumped. The top plug prevents contamination of the cement slurry by the displacement fluid, and provides a positive indication that the cement has been displaced. Plugs need to be compatible with the float collars. Inserts can be used in addition to the float collar to make plug and collar compatible.
• • •
Figure 4-1. Plugs
Note:
The pressure to rupture a diaphragm is approximately 150-500 psi. Do not rupture the diaphragm on purpose at surface.
4.1.1 Botom plugs
Bottom plugs are developed to precede the cement, requiring an internal bypass or flow-through feature. This feature uses a hollow core and a thin membrane that is designed to rupture and permit flow once the plug has seated and a differential pressure is exerted across the membrane.
A bottom wiper plug accomplishes the following:
cleans the casing wall
provides a seat for the top plugs.
• •
22 | Plugs
Figure 4-2. Bottom Plug
4.1.2 Top wiper plug
Top plugs are often used alone and are
designed to withstand the pressures and forces generated when they land abruptly. Top plugs do not have a thin membrane and are designed to prevent any fluid bypass. Top plugs can look very similar to bottom plugs (especially if they are the same color), and often the only way to determine one from another is to turn the plugs upside down and check the inside of the plugs . The top wiper plug
cleans the casing wall
indicates end of displacement
follows the slurry to prevent contamination.
Figure 4-3. Top Plug
The following figure shows the last few moments of a wiper plug's displacement and the position of the various fluids (mud, cement, etc.) in the annulus of the wellbore.
• • •
Figure 4-4. Position of Various Fluids in Annulus
4.3 Nonrotating and rotating wiper plugs
The following three types of wiper plugs do not rotate at the float collar depth.
Figure 4-5. Plug Types
A: nonrotating TOP plug B: standard BOTTOM plug C: standard TOP plug
Figure 4-6 shows a simulated wellbore in which the top and bottom non-rotating plugs have landed at the float collar.
At the bottom of the figure is a magnified view of the top of the bottom plug showing the non rotating profile. Weatherford typically supplies plugs of this design.
• • •
Figure 4-6. Nonrotating Wiper Plugs in Well
4.4 Wiper plug manufacturers
Schlumberger uses three preferred vendors for wiper plugs: Industrial Rubber, Inc. (IRI), Weatherford International Ltd., and Wichita Falls Manufacturing, Inc.
Weatherford
Typical polyurethane cement wiper plugs supplied by Weatherford are shown in both standard and non-rotational configurations. Weatherford bottom wiper plug is shown in red, the top wiper plug is shown in yellow.
Figure 4-7. Weatherford Standard Plug
Figure 4-8. Weatherford Non-Rotating Plug
Wichita Falls Manufacturing, Inc.
Typical cement wiper plugs supplied by Wichita Falls are shown in the standard configuration.
Figure 4-9. Wichita Falls Top and Bottom Plugs
Wichita Falls plugs have distinguishing features between the top and bottom plugs. The bottom
24 | Plugs
plug is orange and has a large hollow inside, whereas the top plug is black and has a small hollow inside.
Industrial Rubber, Inc. (IRI)
Four types of plugs supplied from IRI are shown – from left to right: rubber top (solid) plug, wooden top (solid) plug, orange rubber (hollow) bottom plug, and black rubber (hollow) bottom plug.
Figure 4-10. Top and Bottom Plugs Manufactured by IRI Table 4-1. Sequence of Fluids and Pumps
Sequence of fluids and plugs
starting with first fluid pumped and ending with displacement fluid
One top plug only (liners):
Mud Wash Spacer Cement slurry Top plug Mud
HP-HT cases (when additional spacer behind the plug is required):
Mud Spacer Cement slurry Top plug Spacer behind Mud
One bottom plug only (might be either of the sequences):
Mud Wash Bottom plug Cement slurry Top plug Mud
Mud Bottom plug Spacer Cement slurry Top plug Mud
Mud Wash Bottom plug Spacer Cement slurry Top plug Mud
4.5 Cementing wiper plug sequence
Generic sequence
Cementing plugs should be used whenever possible within the casing and the drillpipe to prevent the intermixing of fluids of different densities inside the casing and to wipe the internal casing walls clean of mud.
The number of plugs to be used depends largely on the method of releasing them; that is, whether they are surface-released or subsea-launched, the type of casing run, and the casing hardware used (float equipment, casing running system, etc.).
To minimize the contamination of fluids inside the casing, the shutdown time (time when equipment is idle and cement remains unpumped) for dropping the plugs must be kept to a minimum. The following placement sequences should be used. If at all possible, it is recommended that two bottom plugs be used on critical jobs (critical is defined by the customer).
The sequences in Table 4-2 start with the first fluid pumped and end with the displacement fluid. The following alternative is recommended if the spacer is in turbulent flow inside the
casing and the density difference between the cement slurry and the spacer is significantly higher than that between the spacer and the mud.
Table 4-2. Alternative Sequence of Fluids and Plugs
Alternative sequence of fluids and plugs
Bottom and top plugs:
Mud Spacer Bottom plug Cement slurry Top plug Mud
Two bottom plugs:
Mud Bottom 1 Wash Bottom 2 Cement slurry Top plug Mud
Mud Bottom 1 Spacer Bottom 2 Cement slurry Top plug Mud
26 | Plugs
Note:
The EXPRES* extrusion plug release system (cementing head) is very rarley used and is no longer supported by the Product Centers.
Conventional cement heads range in size from 2-7/8 to 20 in and range in pressure from 10,000 psi to 1,500 psi. Two construction methods are used to create cement heads. These methods are covered in detail in the following chapters.
Deepsea EXPRES* is a system for launching plugs with subsea wellheads. InTouch has a variety of resources for the use of DeepSea EXPRES. The reference page for the DeepSea EXPRES is in InTouch Content ID# 3280457, DeepSea EXPRES CUH-332 subsea cement head.
Figure 5-1. DeepSEA EXPRES
5.1 Conventional cement heads
Two styles of cement heads are approved for use. Fabricated heads, which can be used up to a maximum of 5,000 psi, depending on the size of the head, and integral heads, which can be used up to a maximum of 10,000 psi, depending on the size of the head. Integral heads have higher-pressure ratings than fabricated heads and therefore require extra care when they are used.
The fabricated head is of approved welded construction, and the manifold has an approved threaded design. The integral head is machined out of one piece of stock, with female ACME
28 | Overview of Cement Heads
threads provided in case a changeover to the 1502 unions is required.
Integral manifolds come in two styles. One is the FMC adjustable manifold that uses the 2-in integral “tee” style valve. The other is an integral manifold machined out of one piece of stock with female ACME threads provided for cases in which changeover to 1502 unions is required. This integral manifold uses standard 2x2-in integral FMC valves.
OCT cement heads still in use are 15 to 25 years old. Any other heads that are made out of cast steel and are not marked with the OCT diamond are older. Many of these heads are marked with the size (e.g, 9 5/8 in) welded onto the OD of the head. OCT (FMC) cement heads should have been removed from service by March 31, 2002 as they are at least 20 years old and no longer approved for operations. To address conventional cement head
equipment requirements, Schlumberger uses of fabricated and integral heads designed and manufactured by Industrial Rubber, Inc. (IRI) in Oklahoma City, Oklahoma this company is the primary and preferred supplier. (For more
information on cement heads, refer to their Web site: http://www.iri-oiltool.com.) The cement heads distributed by IRI have been selected by OSP (Operations Support—Well Services) as the preferred product for Schlumberger. Alternative suppliers may be used if they are specified contractually or if the final destination is UIE in France and/or Hybrid (in California). Hybrid cement heads in the field that were purchased to meet North Sea or contract requirements will remain in service.
The standard associated over-the-collar coupler is the Fast Latch Coupler, which is designed and manufactured by FMC Technologies in Houston, Texas.
A tattle-tale assembly signals that the cementing wiper plug has left the head. The interior of the head is machined to allow
equalization of pressure around the cementing wiper plug. The plug is held in place during cementing by a continuous-type pin assembly. The manifold is composed of FMC’s DR5OW plug valves and 1502 Weco unions.
The complete assembly is machined using alloy steel with traceability for each component and in compliance with ASME and API
specifications.
5.1.1 Conventional cement heads
The Conventional cement heads come in a single-plug and a double-plug cement head, IRI manufactures both types.
Figure 5-2. Conventional Cement Head Types
5.2 Cement head pressure ratings
5.2.1 IRI fabricated cement head (305 and
306 series)
The IRI fabricated cement head is the latest design. Connections on the body are integral type with #8 ACME threads and PolyPak seals. The design eliminates the line-pipe connections that were used in the past. The costs are
much less than for the integral head. The 305 series is a single-plug cement head assembly fabricated type, while the 306 is the double-plug cement head fabricated type.
Single plug head
Figure 5-3. Fabricated Single Plug
Safe working pressures are given in the table below. Note that the bigger the internal diameter of the cement head, the lower the safe working pressure (SWP).
Pressure rating (psi)
From 2 7/8-in to 9 5/8-in (inclusive) 5,000 From 10 3/4-in to 13 3/8-in (inclusive)
Cement head size (internal diameter)
3,000 From 16-in to 20-in (inclusive) 1,500
Table 5-2. Safe Working Pressures
Each head is equipped with continuous pin assemblies, tattle-tale assembly (to signal that the plug has left the head), an extra pump truck connection, and a high-pressure manifold. The complete assembly is machined, using alloy steel, to ASME and API specifications. The standard pressure (fabricated) cement heads can be identified by the straight exterior of the body.
30 | Overview of Cement Heads
5.2.2 IRI integral cement head (307 and
308 series)
The integral cement head design provides a higher pressure-rated head than that of the fabricated type of cement head. All connections to the head are integral type with #8 ACME threads protected by Poly-Pak seals. The 307 series is a single-plug integral cement head, while the 308 is a double-plug integral cement head.
The integral cement head can be identified by the raised bands on the body.
Safe working pressures are given below. Note that the larger the internal diameter of the cement head, the lower the approved working pressure rating.
Pressure rating (psi)
From 2 7/8-in to 7-in (inclusive) 10,000 From 7 5/8-in to 9 5/8-in (inclusive) 7,500
Cement head size (internal diameter)
From 10 3/4-in to 13 3/8-in (inclusive) 5,000 From 16-in to 20-in (inclusive) 3,000
Table 5-3. Safe Working Pressures
Single plug head
Figure 5-4. Integral Cement Head
5.3 Single-plug cement head
The single-plug cement head represents a higher risk to operations because the head must be reloaded with a top plug if two plugs are used.
After the bottom plug has been launched, the operator must interrupt pumping to reload the head, which adds standby time. The valves of the high-pressure manifold are closed, the top cover is removed, and the plug is loaded.
Figure 5-5. Single Plug Cement Head Components
5.4 Double-plug cement head
The double-plug cement head minimizes some of the risks associated with a single-plug cement head, because both plugs are loaded into the head before pressurizing the system. On any conventional head, the operator is exposed to potentially high pressures in the head and treating lines while changing valves and pin positions.
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The cement head manifold houses the valves and conducts slurry and displacement fluid from the cement pump unit to the cement head. Notice in Fig. 6-1 the two lines entering the single-plug cement head from the
high-pressure manifold. In the double-plug manifolds, three lines enter the cement head (Fig. 6-2).
Each of these lines is equipped with a control plug valve that allows the operator to provide flow through each line independently.
A manifold with three valves (rather than two) characterizes the double-plug cement head. Both top and bottom cement plugs are loaded before starting the job. The interior of the head is machined to allow equalization around the cement wiper plug.
Figure 6-1. Single-Plug Cement Head Components
6.1 Manifolds
There are two fundamentally different types of manifolds used with the cement heads currently in service:
One using the 2-in 1502 with integral hammer valve that can be used in either fabricated or integral cement head body the 2-in 5,000 psi. hammer valve that can only be used with a fabricated head.
OCT heads are obsolete and must be removed from service. Before the year 2000, manifolds used on fabricated heads were assembled using V-threads. This type of manifold is obsolete and must be removed from service.
Figure 6-2. Double-Plug Cement Head Components
• •
34 | Cement Head Components
All manifolds currently supplied by IRI cement heads are now considered integral because they use the same thread for assembly. This covers both fabricated and integral cement heads.
Figure 6-3. Threaded and Acme Unions Used for Manifolds
6.2 Caps
The cap is the top-sealing device of the cement head.
Figure 6-4. Cap and Threads
Figure 6-5. Cap
6.3 Pull pin assembly
In a double-plug cement head, both top and bottom plugs are loaded into the cement head before starting the job. These plugs are released by different methods.
The pull pin plug release assembly is the most common type of release. The pull pin must be retracted a specific number of turns to allow the wiper plug to move downward.
The following maintenance bulletins and technical alerts provide information about the pull pin assembly:
Maintenance Bulletin 1056, InTouch Content ID# 2023239, Cementing Head Pull Pin Maintenance
Technical Alert 2000-09, InTouch Content ID# 2040682, Pull Pins in Cement Heads Technical Alert 2001-16, InTouch Content ID# 2062482
Technical Alert 2001-24, InTouch Content ID# 3036444 Part numbers for pull pin assemblies in Industrial Rubber Inc. cement heads.
• • • •
Figure 6-6. Cement Head Pin
Figure 6-7. Cement Head Pin Assembly
6.4 Tattletale
The tattletale is a lever device that indicates that the plug has left the cement head. The tattletale points towards the body of the cement head when the plug is in the head, and it points away from the body of the cement head when the plug has been dropped.
335-1033 BODY
335-1433 SNAP RING,
SHAFT 335-7033SEAT, SUPPORT BALL, TEFLON 335-8033 LOCK RING, SUPPORT BALL 335-2033 HANDLE, SIGNAL 335-3033 SENSING ARM
1. Prior to plug departure the tattletail lever will point towards the cement head body
2. After plug departure the tattletail lever will point away from the cement head body 335-8033
SUPPORT BALL, ARM 335-1333
THREAD SEAL, O-RING (2-330)
335-2033 HANDLE, SIGNAL 335-9405 FLATHEAD SOCKET CAP SCREW (1024X5/3) 335-4033
MAIN SHAFT 335-1133O-RINGS, SHAFT (4 required)
335-8000 LOCK RING, INTEGRAL THREAD
Figure 6-8. Tattletale Components (above) and Operation (below)
6.5 Casing nipple
The casing nipple attaches the cement head to the casing that protrudes above the rig floor. Usually an over-the-coupler fast latch type is used.
6.6 Bull plug
A bull plug is used to connect an extra line when high pumping rates (more than 8 bbl/min, connecting another pump) or displacement rates are required.
36 | Cement Head Components
Figure 6-9. Bull Plug
6.7 Quick-connect coupling
The quick-connect coupling is a device that connects easily and securely to the casing. Its use and characteristics are detailed further in the next sections.
The use of twin-path slings to secure
cement heads to the elevators or bails are a requirement in Standard 5.
Cement heads through size 13-3/8 in are secured by using the TPXC 1500 sling and the Crosby 3-ton hook.
Slings have three main advantages over cable:
They increase the safety margin. A wire rope such as 1/2-in 6x19 IWRC EIP rope can support a 960-lb2 force load when it
drops from 3 ft but fails at a drop of 5 ft. With a twin-path sling the weight is safely supported, even with a 5-ft fall.
Twin-path slings provide three visible means of identifying damage, which will be explained further. The integrity of wire ropes is often difficult to assess, especially in the presence of dirt and oil.
The synthetic slings are lightweight and flexible, making them user-friendly in terms of handling at heights and securing the load.
Figure 6-10. Tattletale for Slings
The black line indicates the limit to which the yellow fiber cord can be pulled to before the sling should be removed from service.
Black limit line
Fiber cord Fiber optic
Twin-path slings (patented by Slingmax) use two hi-tech fiber rope cores that provide each other with backup protection. The two cores are physically separated within the sling. Each core forms a continuous loop, so two conducting paths share the load.
•
•
The slings have a dual cover. If the outer cover is cut, the red inner cover is revealed, which indicates that the sling’s integrity has been compromised. When this happens, the two tattletales built into the sling must be examined. One of these is a solid fiber chord (Fig. 6-10) that extends outside the sling cover for each load path. When the cord is pulled partially under the cover or disappears, the sling is overloaded.
The other tattletale consists of fiber-optic lines that follow the complete loop inside the sling, one fiber for each side. Each optical fiber is continuous and emerges from the sling at the mid-point, as shown below.
Figure 6-11. Optic Lines
Fiber optic
If light can be transmitted from one end of the fiber optic cable to the other, the sling has not been overloaded or damaged and can remain in service.
However, if light cannot be transmitted from one end to the other, the sling must be removed from service.
Note:
The ends of the optical cable may be dirty from use. When performing the light continuity test always ensure that the ends are clean. It may be necessary to cut a very small piece off each end before testing.
For detailed information on the types, costs, order numbers, and weight limits of the slings refer to Maintenance Bulletin 1062-BRestraining Slings for Cement Heads InTouch Content ID# 3562542.
Locations that already have the slings in use can continue to use them on the 16-in through 20 in-heads (TPXC 3000-12 ft). The TPXC 1000 (8 ft with 5-ton hook) can be used on all cement heads up through the 9 5/8-in single or double cement head. This applies to both standard pressure and integral cement heads. A durable carrying case is provided with each set of slings. After each use, the slings should be cleaned, inspected, and placed in the bag. Before inspecting the sling, wash it with soap and water. The slings are approved for washing with a high-pressure washer.
Inspection of twin-path slings
Tattletales should extend to the black line marked across both paths of the sling. If neither tattletale is visible or if neither extends past the black line, remove the sling from service (see Fig. 6-12). If Tell-Tails show evidence of chemical degradation, remove the sling from service and send it to the manufacturer for evaluation and repair.
38 | Cement Head Components
Slings should be inspected to see whether the outer cover is cut or torn. Slings must be removed from service if the white core yarns become exposed. If cuts to the inner red jacket are visible, remove the sling from service immediately and send it back to the manufacturer for repair if possible. Damage to the cover may indicate load core damage.
Inspect the slings for evidence of heat damage. Slings with polyester or Covermax covers should not be exposed to temperatures above 82 degC (180 degF). Cold temperature exposure down to –40 degC (–40 degF) does not affect the strength of the products. Any other temperature to which the
equipment will be exposed should be referred to the manufacturer for approval.
Fiber-optic light transfer determines core integrity. If light cannot be transmitted from one end of the fiber-optic cable to the other end, the sling has been overloaded or damaged (see Fig. 6-12). If deterioration is found, the sling must be removed from service and returned to the manufacturer for evaluation. Test both optic fibers.
•
•
•
Figure 6-12. Sling Inspection
Tell-tails
Black line
Sling overloaded
Slings removed from service that cannot be repaired should be destroyed so that they are completely unfit for future use.
Abrasion, heat damage, or cuts to the cover may indicate a loss of strength to the load core. These slings should not be used until they have been evaluated by the manufacturer.
Slings should be examined throughout their entire length for abrasions, cuts, heat damage, and fitting distortion. If there is any doubt whatsoever about the sling integrity, remove the sling from service. Slings must be visually inspected before every cementing job.
After the job, slings should be packed in the bag provided.
• •
•
• •
Figure 6-13. Slings Bag
Figure 6-14. Slings Fiber Check
Optic fiber
Reflection of light from this end A flashlight shone
into this end
Inspection of Crosby synthetic sling saver shackles (S-253)
Check for wear, deformation, cracks, sharp nicks, and modifications on all Crosby shackles.
The two major wear points on the Crosby S-235 sling saver shackles are at the pull of the bow (D) and the pull of the pin (B) (see diagram). No more than 10 percent of wear of the original dimensions is acceptable on any Crosby shackles, as shown in Fig. 6-15.
Deformation of the Crosby S-253 sling saver shackle can be measured by the overall length of the shackle (A), the width between the ears of the shackle (C), and whether the pin seats fully in the shackle (see Fig. 6-15).
• •
•
Cracks can show anywhere on the shackle, but the pulling surfaces tend to show most deterioration. Sharp nicks on the shackle should be removed to avoid sling damage and failure.
No modification should be made to Crosby fittings without the consent of the manufacturer.
If any indications are observed, the shackle must be removed from service.
A 3.06 in D - width Dim. Tot. + 0.25 - 0.00 + 0.00 - 0.12 + 0.18 - 0.18 + 0.00 - 0.14 B 1.25 in C 1.62 in D 1.38 in width A B C
Figure 6-15. Shackle Inspection
D-width
Inspection of Crosby hooks (5-ton WS-320) Crosby hooks are a part of the sling assembly used for lifting the cement head.
Check for wear, deformation, cracks, nicks, and gouges on all Crosby hooks.
The two major wear points on the Crosby WS-320 synthetic sling saver hooks are at the pull of the eye (B) and the bowl of the hook (D). No more than 5 percent of wear of the original dimension is acceptable (see Figs. 6-16 and 6-17). • • • • •
40 | Cement Head Components A 1.47 in B - width D - width Dim. Tot. + 0.25 - 0.25 + 0.08 - 0.08 + 0.25 - 0.25 + 0.06 - 0.06 B 1.63 in width C 2.00 in D 1.13 in width A C
Figure 6-16. Crosby Hook Inspection
B-width
D-width
Figure 6-17. Hook Deformation Indicators
Deformation indicators
Never use a hook whose throat opening has been widened (which indicates abuse or overload) or whose tip has been bent more than 10 degrees out of plane from the hook body, which is in any other way distorted or bent.
To check for deformations, refer to two strategically placed marks, one just below the shank or eye and the other on the hook tip, to see whether the throat opening has changed.
Use a tape measure to measure the distance between the marks. The marks should align to either an inch or a half-inch increment on the tape measure (see Fig. 6-17). If the measurement does not meet this criterion, the hook should be inspected further for possible damage.
•
Remove any hook with a crack, nick, or gouge from service, and repair it by grinding lengthwise, following the contour of the hook (no more than 5 percent of the original dimension, as determined in table.) For the WS-320 hook, the reference is 2.5 inches.
No modifications should be made to Crosby fittings without the consent of the manufacturer.
If any modification or wear is found, remove the hook from service.
Inspection of Crosby hooks (3-ton WS-320AN) Check for wear, deformation, cracks, nicks, and gouges on all Crosby hooks.
The two major wear points on Crosby WS-320AN synthetic sling saver hook are at the pull of the eye (B) and the bowl of the hook (D). Acceptable wear on a Crosby hook is no more than 5 percent of the original dimensions. (see Figure 6-18). Never use a hook whose throat opening has increased, whose tip has been bent more than 10 degrees out of plane from the hook body, or which is in any other way distorted or bent.
Note:
A latch will not work properly on a hook with a bent or worn tip.
Remove any hook with a crack, nick, or gouge from service and repair it by grinding lengthwise, following the contour of the hook (no more than 5 percent of the original dimensions).
• • • • • • 4.
A 1.47 in B - width D - width Dim. Tot. + 0.25 - 0.25 + 0.08 - 0.08 + 0.25 - 0.25 + 0.06 - 0.06 B 1.63 in width C 2.00 in D 1.13 in width A C
Figure 6-18. Hook Widths
B-width
42 | Cement Head Components
7.1 Cement head prejob checklist
Pre-job checklist
Table 1-1. Prejob Checklist
Use the following cement head prejob checklist to ensure that the cement head job progresses smoothly. (The appendix of this manual provides checklists also for prejob, rig-up, rig-down, and STEM I procedures.) Complete each of the tasks before going to the job location.
STEP
01
Check the size, weight, and thread of the casing. These provide information about the size of the cement head and the adapter to use.STEP
02
Check the adapter thread type and thread gauge quality to make sure they are appropiate for the job.STEP
03
Check the bail size to determine whether to use a single- or double-plug cement head.STEP
04
Determine the expected working pressure of the well as specified in theCementing Minimum Service Quality Standards that can be found in InTouch.
STEP
05
Make sure the plug type is compatible with the cement head and in good condition.STEP
06
Confirm that the plugs meet the requirements for well pressure, temperature, casing weight, and size requirements.STEP
07
Review the maintenance documentation to confirm that the cement head has been pressure tested and inspected in the last 12 months. Cement heads must be pressure tested and threads checked at least once a year as specified in Safety Standard44 | Cement Head Job Execution
5: Pressure Pumping and Location Safety, InTouch Content ID# 3313681.
STEP
08
Inspect the green tagged cement head with the following procedure:Disassemble the manifold from the cement head.
Open each of the hammer valves (make sure they open easily and that they are clean).
The thread-halves should be checked for good seals on all 1502 thread halves.
Pass a bar or run water through each of the thread halves to make sure there is no cement or mud clogging the valves. Do the same for the manifold.
Check the threads of the cement head. If there is mud or cement residue, clean the threads with a wire brush.
Clean the pinhole of the wire tattletale, if one is being used.
Make sure the pull pins open, close, and turn easily. Note the number of turns needed to fully extract. Check that retract and engage fully by checking them visually inside the cement head. 1. 2. 3. 4. 5. 6. 7. 8.
Figure 7-1. Correct Pull Pin Assembly Cement head
OD Pull pin assembly
Thread
Pull pin
Cement head major ID
If the head is a quick-connect, set the quick coupler on the floor and check the O-ring to be sure it is in good condition. Screw the head on, and make sure the fit is correct.
Make sure the thread protector is installed.
Have a spare set of O-rings available. Ensure that there are back up plugs (one top and one bottom).
Once the head is in the pick-up or before the job, always remove the cap and check the O-ring to be sure it is in good condition. With the cap off, check the pin from inside the cement head. Check for full movement and to see if the pins feel loose. If the pin is in working condition, set it in the CLOSED position. If a plug is loaded at this time, follow the steps detailed in 7.1.4 Loading the wiper plug section of this manual.
9.
10. 11. 12.
7.1.1 General job inspection procedure
for cement heads
The following checks are required before cement heads are placed on the ready rack or before they are used on a service job.
Figure 7-2. Cement Head STEM
Cement heads
STEP
01
Read at least two to three previous STEM reports and make sure any pending repairs have been made. Clean all46 | Cement Head Job Execution
threads with solvent and check the threads with casing thread gauge (P/N 518218000).
STEP
02
Remove and clean all caps and check all O-rings. Replace the O-ring in the top cap before beginning the job if it is damaged.Figure 7-3. Damaged Hammer Ears and O-Ring
Figure 7-4. Hammer Ears
STEP
03
Grease all valves and check that they operate properly.STEP
04
Check the plug releasemechanism to see that it operates properly. Ensure that the pin is not bent or damaged. Replace any bent or damaged pin.
STEP
05
Put thread protector on any threads.STEP
06
Verify that the tattletale functions properly and moves freely.STEP
07
Green-tag the cement head with the date serviced and the initials of the person performing the maintenance.STEP
08
Put additional O-rings for the cap, quick connection, and pin in a container with a pressure test chart.STEP
09
Make sure that the cement head's paint is undamaged and make touch-ups as needed.STEP
10
Verify that the white lines across the pull pin are visible.Quick couplings
Quick couplings must be inspected before to every job. Follow the inspection guidelines in the Treating Equipment Manual, Version B, InTouch Content ID # 3013931, Section 8.
STEP
01
Clean the threads with solvent and check them with thread gauge (P/N 518218000).STEP
02
Disassemble the quick-coupling, and check the O-rings and mating surfaces. Replace nicked or pinched O-rings.Install thread protectors, and return to service. Casing swivels
STEP
01
Clean the threads with solvent, and check them with the thread gauge (P/N 518218000).STEP
02
Check swivel rotation for freedom of movement. If movement is restricted, red-tag it, and replace.STEP
03
Grease the casing swivel. First remove the Allen head screw opposite the grease zerk, then grease until the returns out of the bleed port are clean. (For a review on this procedure refer to JET 1, Treating Iron, InTouch Content ID# 4127821).STEP
04
Apply thread protector to threads.STEP
05
Place a green tag on the swivel with the date serviced and the initials of the person performing the service maintenance.Circulating swages
Figure 7-5. Circulating Swages
STEP
01
Clean the threads with solvent, and check them with thread gauge (P/N 518218000).STEP
02
Remove the seal ring from the 1502 connection, inspect and replace. Lubricate seal ring and thread.STEP
03
Check the internal diameter of the swage to ensure that there is no erosion or corrosion that could create a thin wall and decrease the pressure rating of the swage. Do not use threaded swages. A threaded swage is a swage that has the 1502 thread half screwed onto the swage by means of an 11 1/2-V thread. Welded swages are those to which the 1502 Weco connection is attached by welding.48 | Cement Head Job Execution
7.1.2 Safety
Before every cement job, make sure you know and understand all appropriate safety procedures. The following key documents describe the required safety procedures:
Safety Standard 5: Pressure Pumping and Location Safety, InTouch Content ID# 3313681
Standard S013: Mechanical Lifting, InTouch Content ID# 3260276
Standard 14: Power Winches, InTouch Content ID# 3313689
Pressure Management/Planning: Checklist and Data Sheet for Well Services Safety Standard 28, InTouch Content ID# 4090045
7.1.3 Before attaching the cement head
STEP
01
Set the quick-connect coupling into the casing before the casing is raised on the derrick.STEP
02
Clean any mud off the threads of the cement heads. Mud can be picked up by the head while it is moving.STEP
03
Using the winch of the crane (if available) and the help of an operator, unload the head from the truck.• • • •
Figure 7-6. Loading the Bottom Plug
STEP
04
Make sure that the safety slings, a valve bar, and safety chains are ready for use, if necessary. Also have ready a tee and a valve in case you are not going to wash the on top of the plug.7.1.4 Loading the wiper plugs
Make sure that the pull pins are functioning before loading each wiper plug. Reconfirm the number of turns required to fully retract the bottom and top pull pins.
Follow this procedure when loading top and bottom wiper plugs into the cement head.
STEP
01
Ensure that both wiper plugs are present and undamaged.STEP
02
If both plugs are the same color, ensure that the top and bottom plugs are kept apart and are clearly labeled.Figure 7-7. Ensure Type and Position of Plugs
STEP
03
Extract the upper pull pin so that the bottom wiper plug can be loaded. With the bottom (lower) pin fully extended across the internal bore of the cement head, push the bottom plug until it rests on the pull pin.This is the bottom plug (orange) being loaded - notice how the top pull pin is fully extracted to allow the passage of the bottom wiper plug.
This is the top plug (black) being loaded - notice how the top pull pin is fully retracted to support the top plug when it is inserted.
This is the operator retracting the upper pull pin so that the top wiper plug can be loaded.
Figure 7-8. Loading the Bottom and the Top Plug
STEP
04
Be sure to install the bottom plug first. The bottom plug has a hollow core and a diaphragm. The base of the plug must rest on the pull pin.STEP
05
Close the upper pull pin so that the top wiper plug is supported.STEP
06
With the top pin fully extended across the internal bore of the cement head, push the top plug until it seats on the pull pin. Install the top plug last. The top plug is solid. The base of the plug must rest on the pull pin. Have a witness on siteFigure 7-9. Secure a Witness
Before loading the cement head, ensure that one or more of the following individuals are present at the loading:
company representative
drilling superintendent/tool pusher drilling engineer
other client representatives.
Shut the top valve on the manifold. The top valve remains closed and the bottom or middle valve remains open.
• • • •
50 | Cement Head Job Execution
7.1.5 Setting the tattletale
2. After plug departure the tattle tail lever will point away from the cement head body. 1. Prior to plug departure the
tattletail lever will point towards the cement head body.
Figure 7-10. Tattletale
Before dropping the wiper plugs into the cement head set the tattletale to evaluate when and if the wiper plugs have dropped. A malfunctioning cement head can result in serious damage to the well.
STEP
01
Make sure that the tattletale (wire or mechanical) mechanism is not stuck and that the seal is in place and undamaged. If a tattletale cap is available and wire is used, follow these guidelines:For small plugs, wrap a piece of bailing wire around the middle wipers of the plug and push the plug into the head. Set the tattletale and tighten the rubber on the wire. For a flex-plug or a flex-latch in the plug (the flex plug is used on a two-stage job as the first plug), do not load the plug a long time ahead of the job. The flex plug can slip in the cement head and become hung in the pin. For best results, load the plug in the head just before displacing.
Set the mechanical tattletale:
STEP
02
Before the wiper plug is released, the tattletale lever arm (inside the cement head) should be pointing up, and the external indicator should be pointing up towards the body of the cement head.•
•
Whether the plug has departed can be determined by the tattletale lever:
Prior to plug departure, the tattletale lever will point toward the cement head.
After the plug departure, the tattletale lever will point away from the cement head.
7.1.6 Connecting the cement head
Warning:
When attaching the cement head, be careful not to drop any tools inside the casing or around the rig floor.
Always follow these guidelines when taking tools to connect the cement head:
Do not carry any tools that are extremely heavy or big. Tools must be easy to handle. Do not carry any tools or objects in pockets while aloft that could be dropped into
the casing. Make sure that you have a chinstrap on your hard hat.
• •
• •
These combinations are available for both fabricated and integral heads
IRI cement head male ACME thread
IRI Quick coupler ACME thread Casing thread IRI cement head male ACME thread
IRI cement head male ACME thread
FMC fast-latch ACME thread Standard casing pin
IRI quick coupler ACME thread/ FMC Fast-Latch ACME thread FMC Fast-Latch Coupler FMC Fast-Latch Cement head
Figure 7-11. Connection Combinations for Heads
Note:
After the cement head is in position and stabbed into the casing; the supervisor can ask for tools to complete the connection of the cement head. The tools can be delivered to the supervisor in a basket or bag attached to the manifold.
STEP
01
After the casing is in place, connect the head to the quick coupling. If a quick coupling is not being used, connect the head to the casing. When connecting the head, be sure that the plug pin on the head can be backed off because the pin is occasionally trapped in the rig’s elevator bails. Before the manifold is sent up in the derrick make sure the chiksan (swivel), safety cable, and valve bar (used to open and close the cement head valves) are attached to the manifold.Note:
When using a screw-in head, make sure the rig sets the slips and slacks off on the elevators before the head is screwed in. Otherwise, the collar may not fit correctly on the head; a poor fit will result in a poor seal.
STEP
02
Attach the manifold to the head. Be sure that the top valve is shut if there is a plug in the head.7.1.6.1 Securing the cement head
The cement head must be secured whilecement is being pumped during a job. However, if the head separates from the casing, the securing cables will prevent the head from falling and damaging equipment or injuring personnel. The Safety Standards now allow the use of two small slings on single-plug cement heads that are 8-5/8 in and smaller.
52 | Cement Head Job Execution
The slings are used in the choke mode as shown in Fig. 7-12.
Twin-path slings are used now instead of wire rope cable. Even though the slings have a far greater load capacity than the cables used in the past, they can still be cut or crushed. Do not allow the sling to be stretched over sharp corners or between the treating iron and the elevator.
If a cement head slips out of the casing and the sling breaks the fall, that sling must be removed from service until an optical line integrity
check and a mechanical tattletale check are performed.
To use a Slingmax twin-path sling on a cement head, complete the following steps. For
complete instructions, refer to Maintenance Bulletin 1062 “MUST DO” InTouch Content ID# 2023244, Sling for Cement Heads.
STEP
01
Wrap the twin-path sling around the cement head between the manifold nipples (see Fig. 7-13).STEP
02
Pass the sling through itself, forming a choker.STEP
03
Wrap the free end of the sling around the elevator (bail) until snug; then secure back to the sling between the head and bail using the special Crosby hook or shackle.STEP
04
An alternative to Step 3 is to take the loose end of the sling to the upper eye of the elevator bail to take up slack. This can be passed through the eye and hooked back to itself, as in Step 3.Check the following before leaving the derrick after hooking up the head:
Valves are in the top shut, bottom open position.
The valves and pins are accessible for operation. Elevators Treating line Safety sling - as per Maintenance Bulletin 1062
Figure 7-12. Securing the Safety Slings
7.1.7 Pressure testing
When pressure testing, remember to: Flush the lines and remove air pockets Close the bottom valve and pressure test as required (ensure that all valves are fully closed)
Bleed off the pressure at the unit, not against the plugs.
7.1.8 Excessive pressure testing
If the customer makes a change to the drilling program, be sure to conduct a pressure test. If the pressure goes beyond the pressure rating of the head, inform and review the changes on the program with the FSM or cell leader.
• •
• • •
Figure 7-13. Pressure Testing
7.2 Single-stage job
7.2.1 Dropping plugs in a single-stage job
Unless instructed otherwise, all plugs should be released with the cement unit in standby mode (engines idling and pumps out of gear).If a flex plug or latch-in plug is used, load the plug just before displacement begins (“stuff the plug”) while washing up to the pit.
Figure 7-14. Loaded Plugs
To drop a preloaded plug:
When the spacer and washer have been pumped and the pump unit stopped, open the middle valve, release the bottom plug, and close the bottom valve. Resume pumping the cement slurry.
Figure 7-15. Dropping the Bottom Plug, Valves Open in Green
Figure 7-16. Dropping the Top Plug, Valves Open in Green
When the cement pumping is complete, ensure that the pumps on the unit are stopped.
STEP
01
Loosen the tattletale wire seal nut.STEP
02
Turn the pin the required number of turns to release the plug.STEP
03
If necessary, wash the lines.54 | Cement Head Job Execution
STEP
05
Close the middle or bottom valve.STEP
06
Start pumping the displacement mud or fluid slowly.STEP
07
Check the tattletale for plug departure. If in doubt of the departure, review the contingency plan with a company representative; then remove the cement head cap, and check for plug departure.STEP
08
After pumping about 5 bbl (800L) of displacement, open all the valves on the cement head to wash out any cement.Note:
Special permission and instructions from management are required when dropping plugs on the fly (while the cement pump is pumping).
Load plugs by hand:
STEP
01
To load a plug, the valves on the cement head should be closed (you are probably pumping to the pit and washing up). The plug pin should be open. Knock the bull plug off the top of the cap to relieve any suction the cement has on the cap. (If you do not do this, the cement U-tube effect will probably suck the O-ring off the cap down the hole.) Once the bull plug is off you can knock the cap off.STEP
02
Place the plug in the head; use a valve bar to push the plug all the way into the casing or as far into the head as possible (be sure to chain the valve bar securely to the cement head). Then put the cap and bull plug back on the cement head.STEP
03
Repeat these steps to load the next plug.7.2.2 Troubleshooting
7.2.2.1 Top plug fails to bump
The top plug may fail to bump because of an incorrect displacement calculation or poor mud displacement efficiency. If the top plug does not bump:
Figure 7-17. Top Plug Fails to Bump
Check the displacement calculation, including the casing tally and pump efficiency (having the correct pump efficiency before the cement job starts is recommended).
Do not over-displace more than half of the shoe track volume. If the plug is still not bumped, stop pumping and check returns.
1.
7.2.2.2 Tattletale malfunction
2. After plug departure the tattle tail lever will point away from the cement head body. 1. Prior to plug departure the
tattletail lever will point towards the cement head body.
Figure 7-18. Tattletale
After the wiper plug is released, the tattletale points down and the indicator points away from the cement head body. If this fails to occur, notify the client immediately. The correct sequence of events should always be the following:
Prior to plug departure, the tattletale lever points towards the cement head body.
After the plug departure, the tattletale lever points away from the cement head body.
7.2.1.3 Pin pull is stiff
If the pull pin is too stiff to move or if it has been bent, when the wiper plug is launched remove the head and place the plugs in the casing (as needed). Then, replace either the head or the circulating swedge. Then finish the displacing procedure.
Figure 7-19. Pull Pin is Stiff
1.
2.
7.2.1.4 Manifold valve is stiff
If any of the high-pressure manifold plug valves are too stiff or cannot be moved, stop the job. Remove the cement head and attach a circulating swedge or water bushing to the casing while the plug valve is being repaired.
Figure 7-20. Leaking Pin Puller
7.2.1.5 Pressure spikes
If the area around the lower pull-pin begins to leak after the bottom plug had been dropped and while pumping cement slurry, screw the pin back in. Make sure the plug has dropped by checking the tattletale position.
56 | Cement Head Job Execution
Figure 7-21. Manifold Valve Is Stiff
7.3 Two-stage job
On a two-stage job, it is best to load the first-stage plug by hand. The closing plug can then be loaded before the second stage is begun. This is the safest way to ensure that the plugs are dropped correctly.
The first plug in a two-stage job is always a flex plug. This plug needs to be loaded by hand as described in the previous chapter.
1.
Figure 7-22. Flex Plug
After the first stage displacement, drop the opening plug (bomb) with the bail open (do not pump on the bomb until it is at the stage tool).
Figure 7-23. Bomb Landing
Unless the client requests otherwise, load the closing plug immediately after dropping the opening bomb.
Figure 7-24. Closing Plug
2.