10. Downhole Cementing Equipment

Section 10

Downhole Cementing Equipment Table of Contents Introduction..............................................................................................................................................10-3 Topics ...................................................................................................................................................10-3 Learning Objectives .............................................................................................................................10-3 Unit A: Guiding and Floating Equipment................................................................................................10-3 Guide Shoes..........................................................................................................................................10-3 Super Seal™ II Float Shoe...................................................................................................................10-4 Super Seal™ II High-Port Up-Jet (HPUJ) Float Shoe .........................................................................10-4 Super Seal™ II Down-Jet Float Shoe ..................................................................................................10-5 Super Seal™ II Float Collar .................................................................................................................10-5 Insert Flapper Float Valve....................................................................................................................10-6 Backpressure Valves ............................................................................................................................10-6 Pressure Differential Fill (PDF) Float Shoes and Collars ....................................................................10-7 Unit A Quiz ..........................................................................................................................................10-8 Unit B: Casing Attachments ....................................................................................................................10-9 Clamps..................................................................................................................................................10-9 Centralizers...........................................................................................................................................10-9 Wall Cleaners .....................................................................................................................................10-10 Cement Baskets ..................................................................................................................................10-11 Unit B Quiz ........................................................................................................................................10-12 Unit C: Primary Cementing Plugs .........................................................................................................10-13 Bottom Plugs ......................................................................................................................................10-13 Top Plugs............................................................................................................................................10-13 Latch-down Plugs...............................................................................................................................10-14 Unit C Quiz ........................................................................................................................................10-16 Unit D: Multiple Stage Cementing Tools ..............................................................................................10-17 Type-P External Sleeve (ES) Cementer .............................................................................................10-17 Type-H External Sleeve (ES) Cementer.............................................................................................10-18 Stage Tool Plug Sets ..........................................................................................................................10-18 Full-Opening (FO) Multiple-Stage Cementer ....................................................................................10-19 External Sleeve Inflatable Packer Collar (ESIPC) .............................................................................10-20 Unit D Quiz ........................................................................................................................................10-21 Answers to Unit Quizzes....................................................................................................................10-22

10 • 1

Cementing 1

Introduction

Use for Section Notes…

10 • 2

Cementing 1

Unit A: Guiding and Floating Equipment

Introduction During the early stages of the drilling process, the hole will be lined with steel casing to prepare the well for production or deeper drilling. The steel casing provides a smooth bore for the tools necessary to drill and complete the well. The types of downhole equipment discussed in this section contribute to a good cement job; they help ensure a uniform cement sheath behind the casing.

A. Guiding and Floating Equipment

As you learn more about downhole equipment, keep in mind that any item that will be used inside the casing must be made of drillable material.

Upon completion of this section, you should be familiar with:

Topics

B. Casing Attachments C. Primary Cementing Plugs D. Multiple-Stage Cementing Tools

Learning Objectives

•

Functions of downhole equipment

•

Descriptions of the basic types of equipment used downhole

•

Uses and applications of downhole equipment

This chapter covers the following topics:

Unit A: Guiding and Floating Equipment Guiding equipment helps guide casing past ledges and doglegs to the bottom of the hole. Floating equipment allows casing to be run in the hole partially empty, which takes some of the stress off of the rig structure and drawworks. Also, backpressure valves in floating equipment permits the release of pressure in the casing, after the cement job, to reduce microannulus problems. A microannulus may be created when stressed casing (due to internal pressure) is allowed to relax after cement has already hardened and bonded. As the casing contracts, the slight reduction in casing outside diameter results in a very narrow gap between the cement and casing that may allow fluid travel and compromise the isolation of zones.

Collars

•

Backpressure valves

Guide Shoes Guide shoes and down-jet guide shoes have the following primary purposes:

Some of the more commonly used types of guiding and floating equipment will be discussed in this unit. These include: •

•

•

They protect the casing string from the impact associated with landing casing on bottom

•

They direct casing away from ledges, reducing the chance of sidewall cave-in

•

They help casing pass through narrow, deviated holes and areas with hard shoulders

The standard guide shoe has a large-ID hole through its center, allowing maximum cement pumping rates and the passage of self-fill orifice tubes and balls dropped in the casing string. The

Shoes

10 • 3

Cementing 1

Unit A: Guiding and Floating Equipment

rounded nose of these guide shoes is made from high-strength cement that can be drilled out easily with tri-cone rock bits or PDC bits. Down-jet guide shoes have additional side ports in the steel case that allow fluids to discharge through both the cement nose and the ports. The jetting action of the fluid pumped through these ports helps remove wellbore cuttings and filter cake.

Figure 10.2 - Super Seal™ Float Shoe

Super Seal™ II High-Port Up-Jet (HPUJ) Float Shoe The High-Port Up-Jet (HPUJ) float shoe jets the formation face to remove detrimental mud cake and cuttings, increasing the chances of a successful cement-to-formation bond. The high circulation rates and cement flow rates that are possible with the Super Seal™ II float valve allow turbulent flow at the shoe without damaging the float valve.

Figure 10.1 - Guide Shoe

Super Seal™ II Float Shoe The Super Seal™ II standard float shoe attaches to the lower end of the casing string. This float shoe includes the Super Seal™ II backpressure valve assembly, which helps prevent cement in the cased hole from re-entering the casing ID. The plastic valve and stem materials are surrounded by drillable concrete, making the equipment easy to drill out with PDC or tri-cone rock bits. The high-strength, durable rounded nose safely guides the casing to the bottom of the hole. This equipment is available in all tubing and casing sizes with API 8-rd and buttress threads. The standard casing grade is K55 material. Customers can request any casing grade and premium thread by special order.

The HPUJ shoe includes six fluid-discharge ports strategically placed to jet the circulation fluid or cement upward, enhancing fluid turbulence far above the floating equipment. These up-jet ports, along with four (or fewer) down-jet ports, distribute the fluid in the annular space above and below the float shoe, helping prevent channeling near the shoe. Approximately 40% of the fluid pumped through the equipment is discharged at a high velocity through the bottom of the float shoe, removing material in its path and helping maneuver the casing past ledges and tight sections of the wellbore. If the casing string is reciprocated during cementing, cement jetted through the exit ports remove mud cake from the formation face. Field

10 • 4

Cementing 1

Unit A: Guiding and Floating Equipment

reports indicate that the HPUJ float shoe can substantially reduce the number of casing strings requiring secondary squeeze cementing operations. All casing sizes of the Super Seal™ II HPUJ float shoe use the same autofill strap used for the Super Seal™ II float valve. When engaged, this strap allows the casing to fill automatically with wellbore fluid while it is being run in the hole, saving time and reducing the “ram effect” of running casing.

Figure 10.4 – Super Seal™ II Down-Jet Float Shoe

Super Seal™ II Float Collar The Super Seal™ II float collar includes the Super Seal™ II backpressure valve, which prevents cement pumped into the casing/ wellbore annulus from re-entering the casing ID during cementing operations. The float collar is normally installed one or two joints above the float or guide shoe. All casing-size Super Seal™ II float collars include an autofill strap (at no additional cost). This strap, which is installed between the valve and pressure seat, is deactivated by flow rate. The autofill strap allows wellbore fluids to enter the casing with the first joint, reducing surge pressure on the formation and reducing casing fill time from the surface. When the autofill strap is pumped loose with a high fluid rate, the float valve is re-turned to a dependable Super Seal™ II backpressure valve for floating or cementing. The autofill strap will deactivate if the flow through the valve reaches a predetermined rate (4 bbl/min for the 2 ¾ in. valve and 6 bbl/min for the 4 ¼ in. valve).

Figure 10.3 – Super Seal™ II High-Port UpJet (HPUJ) Float Shoe

Super Seal™ II Down-Jet Float Shoe The Super Seal™ II down-jet float shoe includes the Super Seal™ II float valve, which prevents cement backflow from re-entering the casing ID. In addition to the center hole through the float valve, four to six fluid ports are drilled in the outer case below the float valve. These ports direct some of the fluid downward during circulation. Pressurized fluid jets out of the side ports and the guide nose, helping remove cuttings and filter cake, creating turbulence around the shoe, and improve cement distribution and casing-to-formation bonding. Additionally, the external jets on the outer case provide an alternative cement flowpath if the bottom center port becomes plugged with well debris.

10 • 5

Cementing 1

Unit A: Guiding and Floating Equipment

unit includes a weighted plastic valve and plastic orifice tube. The orifice tube holds the flapper open until a weighted plastic setting ball is dropped into the casing. Once the ball reaches the valve seat, pressure is applied to shear out the plastic orifice tube, which allows the valve to close. This equipment operates efficiently in mud systems containing high concentrations of lost-circulation material. The insert float valve is more economical than standard floating equipment but should not be used under any of the following circumstances: •

in wells over 7000 ft

•

where pressures exceed the collapse pressure of the lightest weight range of casing being used (for example, 17 in., 20 lb/ft J55)

•

when bottomhole temperature is more than 200°F .

Figure 10.5 – Super Seal™ Float Collar

Insert Flapper Float Valve The insert flapper float valve is a backpressure check-valve assembly installed between the pin and box ends of API 8-rd or buttress thread casing joints. The insert flapper float valve is used for casing flotation and cementing operations in wells with moderate temperature and depth. It can be used for differential pressures up to the collapse pressure of the lightest weight of J-55 casing in the casing size in which it is run. The insert flapper float valve can be installed in long or short API 8-rd or buttress casing coupling. Because of limited space between the casing box and pin, insert flapper float valves are not available for premium-thread casing. One or more insert valves can be run in a casing string or in conjunction with a standard float shoe or guide shoe.

Figure 10.6 – Insert Flapper Float Valve Self-Fill Unit and Insert Flapper Float Valve

Because they are made from aluminum, insert flapper valve assemblies can be drilled out easily with a medium-tooth, tri-cone rock bit. PDC bits should not be used to drill out insert flapper valves.

Backpressure Valves Backpressure valves were briefly discussed under float collars. They are one way valves that keep the flow of fluid from re-entering the

The insert float valve has a large flow area and can be easily converted to autofill equipment if an orifice self-fill unit is installed. The self-fill

10 • 6

Cementing 1

Unit A: Guiding and Floating Equipment

Automatic fill equipment is used to

casing. Two common types of valves are the flapper and poppet valves (Fig. 10.6). The flapper valve uses a spring-loaded flapper that has a rubber coating around a beveled edge, which seals on a tapered seat. The spring is a low force type (it requires only a small amount of pressure to open the valve).

•

reduce rig time

•

reduce fluid surge effects of running casing

•

prevent the sticking of casing

Flapper type equipment can be converted to automatic fill by installing a fill tube through the middle of the tool. This holds the flapper off its seat.

When pumping stops, the spring pushes the valve back against the seat, preventing fluid from entering the casing.

The diameter of the fill tube can be chosen to somewhat control the flow rate of fluid into the casing. To stop the flow rate and convert from automatic fill to float valve, a ball must be landed on a seat in the fill tube, pressure applied, and sheared out of the valve.

The poppet valve uses a rubber-coated, springloaded valve, which seals on a plastic seat. The poppet is pushed downward by fluid pressure allowing the fluids to be pumped through the valve. Once the pumping has stopped, a shut off is created when the poppet is pushed up against the seat by a spring.

To convert the poppet valve to automatic fill, specially designed stand-off lugs are inserted between the spring loaded valve and the seat. This allows fluid flow to occur through the valve from either direction. To cause the valve to act as a backpressure valve, a specified pump rate must be achieved that will open the valve sufficiently to free the stand-off lugs. The lugs then flow downward from the poppet, allowing the valve to seat when pumping is stopped.

Pressure Differential Fill (PDF) Float Shoes and Collars Flapper Valve Valve

Poppet Valve

Figure 10.7 – Back Pressure Valves To decrease differential pressure in deep holes and minimize the possibility of collapsing the casing, it is necessary to allow some fluid to enter the casing as it is lowered in the hole. Flapper and poppet valve systems can be modified to allow the casing to be filled automatically, but you will have no control over how much fluid will enter; the amount of fluid in the annulus directly affects the amount of fluid which enters the casing.

10 • 7

The pressure differential fill (PDF) float shoe and collar include a float valve. This valve allows casing to be filled while it is run in the hole, and it allows fluid circulation at any time without deactivating the fill unit. PDF float shoes and collars can be run in the same casing string. They allow fluid to enter the bottom of the casing while maintaining a constant differential pressure between the inside and outside of the casing at the floats. This pressure maintains a constant fluid height inside the casing. PDF floating equipment is supplied in the differential-fill mode, and it is ready to be run in the hole. After all casing has been run, a weighted plastic ball is dropped in the casing from the surface and pumped through the tool. This procedure deactivates the differential-fill

Cementing 1

Unit B: Casing Attachments

option. After the ball passes the float collar and/or shoe, the PDF flapper closes against its seat, preventing cement from re-entering the casing ID. The PDF floating equipment is supplied in either a float collar or a float shoe in common casing sizes. All equipment run with these tools must have an ID large enough to allow passage of the weighted ball that releases the backpressure valve. Tool sizes from 4 1/2 to 6 5/8 in. require a 1 3/8 in. diameter ball, while tools 7 in. and larger require a 2 3/8 in. diameter ball. PDF floating equipment should not be used in wells deviated more than 30° from vertical, and it should not be drilled out with PDC bits. PDF equipment cannot be used with Super Seal™ II floating equipment.

Figure 10.8 – Pressure Differential Fill (PDF) Float Shoe and Collar.

Unit A Quiz Fill in the blanks with one or more words to check your progress. 1. The purpose of guiding equipment is to help casing travel downhole without causing ____________________________________________. 2. The purpose of floating equipment is to help prevent ____________________ problems. 3. A (an)______________________ is run on the first joint of casing. 4. Side ports in a guide shoe help to remove __________________________ and ____________________ . 5. The main difference between a guide shoe and a float shoe is that a float shoe contains a _____________________. Fluid can only flow ______________ the casing. 6. A (an)___________________________________ can sometimes be used instead of standard float equipment in a well less than 7000 ft and at bottomhole temperatures less than 200°F. 7. The figure to the right is a (an) ___________________ type valve. 8. Some fluid should enter the casing in deep holes to decrease the differential pressure to minimize the possibility of _______________________.

10 • 8

Cementing 1

Unit B: Casing Attachments

Unit B: Casing Attachments Centralizers

Casing attachments are devices installed on the outside of the casing string to help successfully complete a primary cementing job.

Bow-Spring Centralizers

Included in this unit are •

Clamps

•

Centralizers

•

Wall Cleaners

•

Cement Baskets

Bow-spring centralizers help center the casing in the wellbore during cementing operations, allowing the cement to be evenly distributed around the casing string. The degree to which the casing is centered (standoff) depends on the performance of the centralizer and the spacing between the centralizers installed on the casing OD. Bow-spring centralizers, both welded and nonwelded, provide the following advantages:

Clamps All casing attachments must be installed or fastened to the casing by some method. If they are not installed over a casing collar, then a clamp must be used to secure or limit the travel of the various casing attachments. There are a number of different types of clamps (Fig. 10.9). One type is simply a friction clamp that uses a set screw to keep the clamp from sliding.

•

They help center the casing in the wellbore, allowing even distribution of cement around the casing.

•

They help reduce casing drag on the wellbore during casing running operations.

•

They help prevent differential sticking of the casing.

Another type uses spiral pins that are driven between the clamp and the casing to supply the holding force. Others have dogs (or teeth) on the inside, which actually bite into the casing. Where corrosion problems exist, any clamp that could scar the surface of the casing is unusable. Clamps should draw—not push—the casing equipment into the hole.

•

They increase fluid turbulence at the tool, helping remove filter cake from the wellbore.

•

They can be run through hole restrictions in the wellbore or through smaller casing strings that are cemented in the well, thereby centering the casing below the restriction.

Welded Bow-Spring Centralizer Welded bow-spring centralizers are available in two styles: slip-on and hinged. Slip-on centralizers are manufactured with solid end rings, requiring the centralizer to be slipped on the casing OD during installation. Hinged centralizers are manufactured in segments, allowing the centralizer to be installed easily around the casing OD. Hinge pins hold the segments together during installation. All welded bow-spring centralizers are manufactured to API Specification 10D.

Figure 10.9 - Clamps

10 • 9

Cementing 1

Unit B: Casing Attachments

The dual-contact (double bow) welded centralizer is designed for small-clearance casing-to-hole size applications. The centralizer will perform as a standard bow centralizer in holes up to 1/2 in. smaller than the centralizer’s nominal OD. When run in holes less than 1/2 in. smaller than the OD, the center of the centralizer contacts the casing OD, performing as a rigid centralizer. Because of its high restoring force with very little spring deflection, the dualcontact centralizer is excellent for deviated and horizontal wellbores. The dual-contact centralizer should only be installed between a collar and stop ring— never over a casing collar.

Centralizers with turbofins attached to each bow spring are designed to create localized turbulent fluid flow at the centralizer. The turbofins divert the fluid flow, more evenly distributing cement around the casing. All welded and nonwelded bow-spring centralizers are available in most common hole/casing sizes.

Figure 10.11 – Nonwelded Bow-Spring Centralizer

Figure 10.10 – Welded Bow-Spring Centralizer

Wall Cleaners

Nonwelded Bow-Spring Centralizer

Since drilling fluid and cement should not be mixed together, good cement bonds between casing and cement and between cement and formation depend upon removal of the filter cake from across formations.

Nonwelded bow-spring centralizers are available in the hinged style only. The bow springs of this centralizer are attached to the end rings without welding. The centralizer bow end is connected to the end rings with a locking tab that bears the load force on the centralizer. The centralizers are supplied in hinged segments joined by hinge pins in each segment. All nonwelded centralizers meet or exceed the requirements of API specification 10D, which dictates the minimum restoring and maximum starting forces for centralizers for various casing/hole size combinations.

10 • 10

Wall cleaners or scratchers (sometimes called mud stirrers) are installed on the outside of the casing to mechanically remove mud filter cake from the wall of the hole with spring steel spikes or cables. Mechanical cleaners on the casing agitate the mud and make it easier to displace. The motion of the scratchers breaks the gel strength of the mud in the annulus and helps thin the fluid so that it can be displaced out of the hole. Mud removal is also helped by pumping the cement

Cementing 1

Unit B: Casing Attachments

either rotation or reciprocation during the circulating and displacing operations.

slurry at a rate high enough to create turbulent flow. Two common types of scratchers are rotation and reciprocation. The rotation-type scratcher (Fig. 10.12) cleans the formation when the casing is rotated at about 15 to 20 rev/min. A continuous length of scratchers is needed across the zones to be cleaned.

Cement Baskets Cement baskets are also installed on the outside of casing. They help support some of the hydrostatic pressure that the cement slurry produces until it sets and protect the producing formation against cement contamination. A cement basket has a canvas or metal liner supported by steel staves (Fig. 10.13). This canvas liner filters out the cement solids, which may form a bridge between the casing and hole. The maximum amount of pressure that any cement basket should ever be expected to hold is approximately 50 psi. A cement basket should be able to travel the full length of the pipe joint.

Wire Type

Cable Type

Cable-Type

Wire-Type

Figure 10.12 - Scratchers The reciprocation-type scratcher has either long steel spikes (Fig. 10.12) or a cable (Fig. 10.12). These devices scratch or clean the formation as the casing is picked up 10 to 15 ft off the bottom of the hole. Be careful—some reciprocation type scratchers can be installed upside down and would be useless when they reach the producing formation. It is good practice not to have scratchers working across a lost circulation zone, since the filter cake and lost circulation material should not be removed. However, it is possible to run the reciprocation type (no cable type) scratcher in a lost circulation zone with minimal disturbance of the filter cake.

Figure 10.13 – Cement Basket Cement baskets are used

Movement of the casing, in addition to the use of mechanical cleaners, greatly increases the ability of the cement slurry to more completely displace the mud and prevent mud channels through the cement. This movement can be

10 • 11

•

above weak zones that may break down under the hydrostatic pressure of the cement slurry

•

for cementing casing through a shoe joint to provide extra support for the column of cement.

Cementing 1

Unit C: Primary Cementing Plugs

Unit B Quiz Fill in the blanks with one or more words to check your progress. 1. If a casing attachment is not installed over a casing collar, then a (an) _____________ is used to fasten the equipment to the casing. 2. If you’re working on a well that will likely have corrosion problems, you’ll want to avoid the use of any clamp that could ____________ the casing, like a clamp which has ________________. 3. A uniform cement sheath around the casing largely determines the effectiveness of the __________________ between the wellbore and casing. 4. The casing attachments used to center the casing in the hole are called _______________________________________. 5. Scratchers are used to mechanically remove ________________ from formations. 6. Rotation type scratchers clean the formation when the casing is___________. 7. Reciprocation type scratchers clean the formation when the casing is ______________________________. 8. In addition to using mechanical scratchers, mud displacement is also helped by the ___________________ of cement, and the _______________________ of the casing during a cement job. 9. Cement baskets support some of the _________________________, which the slurry produces until it sets. They have a ____________________ liner, which filters out cement solids that can form a ___________________between the casing and the wellbore. 10. Cement baskets are usually used above a ________________________.

10 • 12

Cementing 1

Unit C: Primary Cementing Plugs

Unit C: Primary Cementing Plugs Plugs used in primary cementing minimize cement contamination in the casing by wiping the casing clean and serving as a barrier between wellbore fluid and cement. Included in this unit are •

Bottom plugs

•

Top plugs

•

Latchdown plugs

Top Cementing Plug

Casing

Accumulation of mud-contaminated cement from wiped away boundary layer

Cement Slurry

Boundary Layer of Mud

Bottom Plugs

Mud

The function of the bottom plug is to enter the casing ahead of the cement slurry. It wipes mud and solids from the casing wall and keeps those solids ahead of the plug. Bottom plugs are almost always used in primary cementing, except when lost circulation materials are being run with the cement.

Figure 10.15 – Top plug run without a bottom plug.

When the bottom plug reaches the float collar or float shoe, the differential pressure between the inside of the casing and annulus ruptures the diaphragm on top of the plug to allow the slurry to flow out of the shoe and up the annulus. The plug body is strong enough to withstand the forces of impact and the differential pressure to rupture.

Top Plugs

Top Plugs A top plug is pumped down by displacement fluid after all the slurry has been pumped (Fig. 10.15). It prevents the displacement fluid from channeling through the more viscous cement slurry. Top plugs have no diaphragm and fluid can not be pumped through them. When it reaches the top of the bottom plug, pressure will build up and indicate that the job is complete. Although the top and bottom plugs perform somewhat the same function (separating two fluids), they are quite different structurally (Fig. 10.16).

10 • 13

Bottom Plugs

Figure 10.16 – Cross-section of cementing plugs.

Cementing 1

Unit C: Primary Cementing Plugs

Top plugs have rubber wipers to wipe the casing and can withstand considerably more pressure. To help with easy identification, top plugs are black and bottom plugs are red. Top and bottom plugs have a solid core of plastic.

Latch-down Plugs

The maximum pressure that the baffle will withstand is dependent upon the proper make-up of the casing joints and the weight range of the casing. A differential of 3,000 psi should not be exceeded in any light weight casing. Higher differential pressures are allowable in heavier weight casing with a maximum of 5,000 psi in the heaviest weights.

Latch-down plugs are usually used with tubing, casing and interstring cementing; however, they may also be used with conventional casing float equipment. The latch-down plug functions as a top plug, and its snap ring locks into a groove in the baffle when it is pumped down after the job (Fig. 10.17). The latch-down feature helps ensure that the cement and top plug will not move back up the casing. The Latch-down Casing Plug and Baffle may be used above most conventional floating equipment to help control fluid and pressure from below. The Latch-down plug may also be used when there is no floating equipment run on the casing string. Prevention of fluid entry into the casing string also permits immediate release of surface pressure when the cement column has been pumped in place. Additionally, the latchdown feature helps assure that the cement or top plug will not back up the casing which might necessitate drilling out if completions are made close to the float collar.

Figure 10.17 – Latchdown plug and baffle. The latch-down baffle may be installed either on top of the float shoe or float collar, or in any casing collar above a float collar. It is held in place by the thread end of the casing. A rubber seal on the plug provides a fluid seal from both directions.

The baffle is installed either on top of the float or in the desired casing collar above and held in place by the pin end of the casing. A rubber gasket seals against the upper joint and the coupling threads. The latch-down plug acts as the top cement plug and follows the cement slurry down the casing to reduce the possibility of contamination or channeling with the drilling mud or fluid used to displace the cement. When the plug reaches the baffle, normally 500 to 1,000 psi above circulating pressure forces the latching nose of the plug into the baffle and locks it in place.

Instead of a float collar, a latch-down plug may be used in conjunction with a guide shoe to save rig time.

10 • 14

Cementing 1

Unit C: Primary Cementing Plugs

Summary of Downhole Equipment Type of Equipment

Major Function(s)

Location

Guide Shoe

To guide casing into well To help protect casing ends

First joint of casing

Float Shoe

Same as guide shoe To prevent fluid or cement flowback

First joint of casing

Baffle Collar

To provide a landing seat for plugs

1-3 joints above shoe (depending on depth of well)

Float Collar

Same as baffle collar To prevent fluid or cement flowback

1-3 joints above shoe

Insert Float Valve

Same as float collar

In casing collar

Back Pressure Valve

To prevent fluid or cement flowback

In floating equipment

Automatic Fill Valve

To automatically allow fluid into the casing to eliminate rig downtime cause by stopping to fill the casing To reduce ram effect

In float shoes and collars

Differential Fill Valve

To allow fluid to enter casing to decrease differential hydrostatic pressure

In float shoes and collars

Clamp

To fasten attachments

As required

Centralizer

To center casing in hole

1 per joint from 200 ft. above formation to 200 ft below it, 1 per 3 joints in open hole

Wall Cleaner

To remove mud filter cake from wall of hole

From 100 ft above producing formation through it

Cement Basket

To help protect formations from hydrostatic pressure of cement until it sets

Above weak formations

Bottom Plug

To Act as a mechanical spacer between mud and cement slurry

Between well fluids and cement

Top Plug

To act as a mechanical spacer between cement slurry and displacement fluid

Between well fluids and cement

Latch-down Plug

Same as top plug

Between well fluids and cement

Multiple Stage Cementing Tools

To cement in two (or more) stages

Depends on hole conditions

Formation Packer Equipment

To pack off formations To isolate zones

Depends on hole conditions

10 • 15

Cementing 1

Unit D: Multiple Stage Cementing Tools

Unit C Quiz Fill in the blanks with one or more words to check your progress. 1. Primary cementing plugs minimize _____________________ by _____________ the casing clean. 2. These plugs serve as a (an) _____________ between fluids and cement. 3. A bottom plug enters the casing _______________ the cement slurry. The _________________ pressure between the inside of the casing and the annulus causes the plug(s) ________________ to rupture. 4. Bottom plugs are almost always used in primary cementing, except when ______________________________________ is (are) being run. 5. A top plug enters the casing ______________________ the cement slurry. When it seats on/at the _______________________, pressure will increase. This indicates that cement placement is ____________________. 6. _____________________ are black and have a deep cup on top; ______________________are red and shallow. 7. A (an)_______________________ plug functions in the same way as a top plug, but it has a (an)______________________, which locks into a groove in its baffle. 8. To save rig time, you might use a latchdown plug in conjunction with a guide shoe instead of a (an) _______________________.

10 • 16

Cementing 1

Unit D: Multiple Stage Cementing Tools

Unit D: Multiple Stage Cementing Tools During multiple-stage cementing, cement slurry is placed at predetermined points around the casing string in several cementing stages. Multiple-stage cementing can be used for the following applications:

• heavy-duty seals and backup rings that prevent seal damage during operations • compatibility with three-stage cementing applications

• cementing wells with low formation pressures that will not withstand the hydrostatic pressure of a full column of cement

Type-P External Sleeve (ES) Cementer

• cementing to isolate only certain sections of the wellbore • placing different blends of cement in the wellbore • cementing deep, hot holes where limited cement pump times restrict full-bore cementing of the casing string in a single stage Halliburton manufactures two types of external sleeve (ES) stage cementers: the Type-P ES cementer, which is a plug-operated stage cementer, and the Type-H ES cementer, which is a hydraulically opened stage cementer. Both the Type-P and the Type-H cementers have the following features:

Type-P external sleeve (ES) cementers can be used in most vertical wells, regardless of depth, pressure, or temperature. The Type-P cementer should not be used in wells deviated more than 30° from vertical when using a free-fall opening plug. Otherwise, the free-fall opening plug will not fall by its own weight through well casing. Type-P ES cementers are available in 4 1/2 to 20 in. casing sizes. The standard case material grade is L-80 steel. Other casing grades can be provided at the customer’s request.

• short, single-piece mandrel design without threaded or welded segments • field-adjustable opening and closing pressures • clear surface indications of opening and closing • smooth bore after drillout with no exposed sleeves to interfere with the operation of workover tools on subsequent trips in and out of the casing strings • drillability with either PDC or roller-cone rock bits • compatibility with second-stage bottom plug sets

Figure 10.18 - Halliburton Type-P External Sleeve (ES) Cementer

• external closing sleeve that is locked closed by the top cementing plug

10 • 17

Cementing 1

Unit D: Multiple Stage Cementing Tools

During cementing operations, the first-stage cement is mixed and pumped into the casing in a conventional manner. The first-stage shutoff plug, which is launched in the casing after the first-stage cement, lands on the shutoff baffle installed on the float collar. This shutoff plug provides a positive shutoff, which helps prevent cement over displacement around the shoe joint. After the first-stage cementing operation is completed, a free-fall opening plug is dropped down the casing ID to land and seal in the cementer. Pressure applied to the casing opens the cementer, allowing wellbore fluid to be pumped into the casing/wellbore annulus. Fluid circulation to the surface is normally maintained until the first-stage cement has set up in the annulus. The second-stage cement is then pumped through the open cementer ports, followed by a second-stage closing plug. The closing plug seats in the cementer, and pressure is applied to the casing to close the tool. After both stages are cemented, the cementer seats, and plugs are drilled out with a rock bit or a PDC bit.

Type-H External Sleeve (ES) Cementer The Type-H external sleeve (ES) cementer is a hydraulically opened stage cementer that can be used in most wells, regardless of depth, pressure, or temperature. Although the Type-H ES cementer operates much like a Type-P cementer, it can be opened with internal casing pressure in addition to the free-fall plug after the first-stage shutoff plug lands. This design feature saves time by eliminating the need for dropping a freefall plug from the surface. A baffle adapter is recommended in the casing string above the float collar to seat the first-stage shutoff plug.

Figure 10.19 – Halliburton Type-H External Sleeve (ES) Cementer plug dropped through the casing ID. The TypeH cementer can be used in highly deviated wells, in horizontal wells, and above an openhole completion or slotted liner. After the secondstage cementing operation, a second-stage closing plug pumped behind the second-stage cement closes the cementer. Lock rings in the external closing sleeve lock the cementer in the closed position. After both cementing stages, the cementer seats, and plugs are drilled out with a roller-cone rock bit or a PDC bit. Type-H ES cementers are available in 4 1/2 to 20 in. casing sizes. The standard material grade is L-80 grade steel. Other grades can be provided at the customer’s request.

Stage Tool Plug Sets

When the first-stage cementing plug has seated, casing pressure can be applied to hydraulically open the Type-H ES cementer. Normally, the cementer should be opened immediately after the first-stage cement is pumped and the shutoff plug has been bumped. If the well is deviated less than 30° from vertical, the Type-H ES cementer can also be opened with a free-fall

Plug sets for operating both Type-P and Type-H cementers must be ordered separately from the cementer. The individual components of each plug set depend on the type of tool to be operated.

10 • 18

Cementing 1

Unit D: Multiple Stage Cementing Tools

A standard plug set for two-stage cementing consists of the following equipment: • a shutoff baffle installed on top of the float collar (for 8-rd and buttress) • a shutoff plug (for both Type-P and TypeH cementers) • a free-fall opening plug (required for the Type-P cementer; optional for the Type-H cementer) • a closing plug (for both Type-P and TypeH cementers) • a baffle adapter installed one or more joints above the float collar (for the TypeH cementer)

Full-Opening (FO) MultipleStage Cementer The full-opening (FO) multiple-stage cementer is used to place an indefinite number of cement stages or other fluids at selected points along the outside of a casing string. An indefinite number of FO cementers can be run in the casing string. Standard material grade is L-80. Other grades can be supplied at customer’s request. When one or more FO cementers are run in the casing string, the first stage of cement can be pumped in the conventional manner. All subsequent cementing stages are pumped through a workstring run inside the casing. Shifting tools run 8 to 10 ft apart on the workstring are used to open or close the FO cementer. Unlike plug-operated or hydraulically opened stage cementers, FO cementers provide the following benefits: • They do not require operating plugs, eliminating the need for drilling out after cementing.

Figure 10.20 – Halliburton Type-P Stage Tool Plug Set

• FO cementers can be used to test, treat, and evaluate a zone in the well before it is closed. • Multiple FO cementers can be run in the same casing string. • Operators can open and close these tools as many times as necessary. A packoff between the workstring and casing is required to direct fluid out the open ports of the FO cementer.

Figure 10.21 – Halliburton Type-H Stage Plug Set Use of a baffle adapter is the preferred method when using a Type-H cementer with a first-stage bottom plug.

FO cementers are available by special order for any casing grade or premium thread. For pricing information, customers must provide information about casing OD, thread type, weight, grade, and hole size.

Wells can also be cemented in three stages with two cementers and a three-stage plug set. A three-stage plug set must be ordered separately from the cementers.

10 • 19

Cementing 1

Unit D: Multiple Stage Cementing Tools

damage during inflation. This inflatable packer element allows packer differential pressures up to 4,000 psi. The ESIPC is commonly used in horizontal well applications for cementing casing in the bend radius or vertical portion of the wellbore above an openhole completion or a slotted liner. The packer element is inflated to prevent cement from flowing downhole when it is pumped into the annulus above the tool. The Type-H ESIPC is available by special order for any casing grade or premium thread. For pricing information, customers must provide information about casing OD, thread type, weight, grade, and hole size.

Figure 10.22 – Halliburton Full-Opening (FO) Multiple-Stage Cementer

External Sleeve Inflatable Packer Collar (ESIPC) The external sleeve inflatable packer collar (ESIPC) is a combination of the ES (Type H or Type P) cementer and a casing inflation packer. This tool provides controlled packer element inflation through the stage-tool opening seat, eliminating hydraulic valving bodies normally used with inflatable packer elements. The rubber inflatable packer element is constructed with reinforcing metal slats to reduce packer element

10 • 20

Figure 10.23 – Halliburton External Sleeve Inflatable Pack Collar (ESIPC) – Type H

Cementing 1

Unit D: Multiple Stage Cementing Tools

Unit D Quiz Fill in the blanks with one or more words to check your progress. 1. Multiple stage cementing tools are used when you want to cement behind the same casing string in ___________ stages. 2. The decision to cement in multiple stages would be made when high hydrostatic pressure might cause the _________________ to break down. 3. If the Type-H ES cementer doesn’t open with _________________ pressure, a _____________________ can be dropped if the well is not deviated more than _______. 4. During the second stage, cement is displaced through _______________ in the multiple stage tool. 5. A multiple stage tool called a __________________________ has two sleeves which are operated _____________________. One sleeve moves to uncover the __________ and the other moves to close the _____________________. 6. The first part of the plug set to enter the hole when the free fall method is used is the _______________________. 7. Once the opening plug has landed, the Type-P ES cementer is opened by ___________________. 8. Unlike the ES cementers, the FO cementer operates _____________________ and can be opened and closed _________________________________. 9. Formation packer equipment is used when you want to ________________ cement from flowing _____________________.

10 • 21

Cementing 1

Unit D: Multiple Stage Cementing Tools

Answers to Unit Quizzes Items from Unit A Quiz

Refer to Page

Items from Unit C Quiz

Refer to Page

1. damage to hole or casing

10-3

1. contamination, wiping

10-14

2. overweight

10-3

2. barrier

10-14

3. float shoe

10-4

3. ahead, differential, diaphram

10-14

4. wellbore cuttings, filter cake

10-4

4. lost circulation materials

10-14

5. backpressure valve, into

10-4

5. after, bottom plug, complete

10-14

6. insert flapper float valve

10-6

6. Top plugs, bottom plugs

10-15

7. flapper

10-7

7. latch-down, snap ring

10-15

8. collapse

10-7

8. float collar

10-15

Items from Unit B Quiz

Refer to Page

Items from Unit D Quiz

Refer to Page

1. clamp

10-10

1. several

10-17

2. scar, dogs (teeth)

10-10

2. formation

10-17

3. cement

10-10

3. hydraulic, free fall plug, 30°

4. centralizers

10-10

10-17, 18

5. filter cake

10-12

4. ports

10-18

6. rotated

10-12

5. Type-H ES Cementer, hydraulically, ports, ports

10-18

7. picked up

10-12

6. shut off baffle

10-19

7. pressure

10-18

8. mechanically, as many times as necessary

10-19

9. prevent, downward

10-20

8. pumping rate, movement

10-11,12

9. hydrostatic pressure, canvas, bridge

10-12

10. weak zone

10-12

10 • 22

Cementing 1