• Author / Uploaded
• Sudish Bhat

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Cementing

Inner-String Cementing Innovative Equipment and Techniques for Cementing Large-Diameter Casing

Halliburton’s inner-string cementing equipment allows cementing large diameter strings through drillpipe or tubing that is inserted and sealed in floating equipment. This method is sometimes less costly than cementing large casing using the conventional plug displacement method.

Advantages In addition to potential cost savings, the inner-string cementing method provides the following advantages: • Large-diameter cementing plugs are not required.

Method 1 should be performed when using a sealing adapter and a special baffle collar, float collar, or float shoe that has a built-in sealing sleeve to provide a receptacle for the inner-string sealing adapter. Concrete retains the sealing sleeve and valve within the floating equipment. The floating equipment concrete top is tapered to help guide the sealing adapter into the sealing sleeve. When using this method, a centralizer is on the inner-string directly above the sealing adapter to help ensure that the adapter enters into the sealing sleeve properly.

• By pumping through the smaller inner string, cement contamination resulting from channeling inside the casing can be reduced. • Cement is discharged outside the casing much faster after mixing, reducing the risk of the cement slurry within the casing having a highly-accelerated setting time. • Reduces the amount of cement that has to be drilled out of large-diameter casing. • Less circulating time is required with inner-string cementing.

There are three basic methods available for performing inner-string cementing. Each relies on Halliburton’s proven line of Super Seal II® floating equipment. Methods include (1) Super Seal II float collar with sealing sleeve, (2) Super Seal II float collar with sealing sleeve and latchdown seat, and (3) standard Super Seal II float collar. Super Seal II equipment offers these benefits:

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Methods

• Reduces cement waste. • Reduces cement drillout time. • Eliminates large-diameter cement plugs. • Reduces slurry placement time. • Drillpipe latchdown plugs are available.

Method 1—Super Seal II Float Collar with Sealing Sleeve

Additional equipment indicating ball or latchdown plug catchers can be used in the inner string to provide additional wiping or indications while an inner-string cementing job is performed.

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Method 2 is employed when using a sealing adapter and a special baffle collar, float collar, or float shoe that has a built-in sealing sleeve with a latchdown plug seat. The sealing sleeve provides a receptacle for the inner-string sealing adapter on the top and a smaller bore to latch and seal the nose of a latchdown plug on the bottom end. This combination sleeve is molded within the floating equipment concrete. The concrete is also tapered on top to provide a stab-in guide for the inner-string sealing adapter.

Method 3 is performed when using an adapter with a flatface seal that will seal on any floating equipment that contains a flat surface of concrete. You can use this method to perform inner-string cementing on any standard float equipment, including Super Seal™, PDF™, or Super Seal II equipment having either a 2 3/4- or 4 1/4-in. valve.

After the inner string is retrieved, the latchdown plug serves as a backup to any backpressure valves that may be located in the casing string below. Although a backpressure valve is not absolutely necessary when using a latchdown plug, it provides a double check against cement backflow.

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Pressure may be applied inside the casing immediately after landing the latchdown plug and the sealing adapter can be pulled from the sealing sleeve. This inner-string cementing method is used for cementing the first stage where equipment, such as a full-opening (FO) cementer, requires pressuring inside the casing.

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Method 3—Standard Super Seal II Float Collar

Method 2—Super Seal II Float Collar with Sealing Sleeve and Latchdown Seat

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