Float nipple float shoe

3-1/2 " stage collar

一、Application

3-1/2”Drilling stage cementing tool is a special equipment which divided the cementing job for twice. It’s mainly used for the following condition.

1． A large amount of cement

2． The stratum cannot bear too much fluid column pressure

3． Seal off special horizon

4． Prevent air channeling after cementing  

5． The temperature difference is too big between interval isolation ,cement slurry performance is not easy to adjust.

二、Structure

3-1/2 ˝（Ф88.9）stage cementing tool is mainly composed by two stage collar(body)、

Flexible plug、flexible plug seat(bump pressure seat)、gravity type open plug and closing plug.

三、Performance feature

1．The open plug seat and closing plug sleeve with left-hand to connect the threads, in case of rotating when drilling the open plug seat

2．Special organization prevent closing seat closed ahead of time.

3．closing seat have a special organization, after the closing seat close the circulation hole, the special organization prevent closing seat retrogress, to achieve permanent close.

4．Carrying out the opening and closing, there is no small cavity liquid compression.

四、Technical parameters

表1(sheet 1)

五、Operating principle

1．Discontinuous graded cementing operating type

After the first level cementing, release the flexible plug, replace the mud, when the Flexible plug touch the pressure release the wellhead pressure, and put gravity type open plug in. open pump to give pressure after the gravity open type plug sit by the free fall into the seat, open the shear cut and the plug seat and going down with closing sleeve and closing plug seat to open the loop hole, build cycle and loop out the needless mud adhering the 2stage cementing collar

After the two-stage cementing, release the closing plug to replace the mud. Keeping pressure after the closing plug down to the seat, the closed shear pin cut and go down with closing sleeve, the open plug seat, closing plug seat to close loop hole. Keeping pressure to 12 mpa, close the plug will cut short shear and go down with gravity plug, the special organization prevent closing seat retrogress, to achieve permanent close.

六、 Delivery state

The 3-1/2 "stage collar is packed in double boxes. One packing case contains stage collar body, the other packing case contains stage collar accessory flexible plug, gravity type open plug and closing plug, etc.

Note: (1) The user has no special requirements, the accessories well equipped out of factory according to the operating type of Non-continuous stage cementing.

七、Warehousing, transportation and maintenance

1. The products should be stored in a flat, dry warehouse, the parts should be properly kept, prevent the rain, sun and sea water erosion; 

2. Before using the product please not open the box as much as possible, do not tear the plastic bags;

3．Handle with care when transporting prohibited throw, hit, bruised body to prevent the two-stage hoop deformation;

4．Product storage time should not exceed 1 year.

八、Recommended operating procedures and matters needing attention

（一）、Preparation

1． Check the two-stage cementing device and its accessories carefully , especially the body up and down the seals threaded and accessories

2．The casing pipe must according to standard size.

    According to the order well casing string cementing design structure: float shoe +float collar+ Landing Collar（including flexible plug seat) + casing +Centralizer +Stage Collar +Centralizer +Casing+ cement head.

Note:  ① Flexible plug seat placed inside the collar, no length

        ② Two stage cementing device ontology sleeve length should be not less than 80 m below

  ③Two stage cementing device location should choose the rules of formation stability, caliper, not easy to collapse

（二）、Down casing pipe and stage tool

1．According to the order into the casing and accessories, according to the standard on enough torque. Accessories and grading ring and the casing pipe connection should wear thread binder.

2．Appropriate control casing lowering speed, every 10 root tube filling full set under the mud.

3．The grading ring fluctuation should be continuous and elastic 3 ~ 5 joints of casing centralizer.

4．When hanging on the rig note that prevent bump stage collar  

Note: Do not use a crowbar penetration inside the two-stage cementing be moving or lifting

5．When stage collar  devolved into the well please slowly to prevent the wellhead and other devices for two-stage cementing body squeeze and collision.

6．After casing down to connect cement head and cementing pipelines, flow rate circulation from small to large to prevent leakage strata hold.

（三）、The cementing operation

A．When using non-continuous construction stage cementing ways:

1．The flexible plug installed in the cement head.

2．After the end of the cycle according to the design requirements for the first stage of cementing cementing operations.

3．Pressure flexible plug, touch pressure to replace the mud.

(Note: To prevent malfunctions of the float collar, float shoe resulting in mud reflux, replace with the high density mud below the Stage collar)

4．Stop the pump, the pressure is released from the wellhead, the gravity-type open cast plugs (usually falling speed 60m/min), will close the plug installed in the cement head.

5．When the plug is expected to sit on the gravity grading plug hoop open seat, pump pressure - open graded hoop establishment of recycling.

Note: The opening pressure may have errors. If failed, generally due to the gravity open plug is not sit on the seat, release the pressure, wait. If the gravity open plug has been sit on the seat, still can not open, gradually increase the pressure until opened.

6．Circulating wellbore.

7．For the second stage cementing operations as the cementing design requirements

8．Pressure closing plug(Press the close plug with a 0.5-1m³ mud to making up the leak proofness of two-stage collar) to replacing mud, touch pressure. Gauge pressure shall be the final cycle pressure + additional pressure. Additional pressure should be ≥ stage collar closed pressure +2.0 MPa.

Note: Under conditions allow additional, increase the closed additional pressure to facilitate stage collar off.

9．Stop the pump, release the pressure from the wellhead, check the closing sleeve has been closed or not. If back-flow continued, keeping closing. The second additional pressure should be greater than the first 3 ~ 5Mpa. If still fail, then close the well and wait for coagulation.

10．Unloading manifold , cementing finished.