System fills casing, annulus during lowering operation

Method eliminates swedge, plug, cementing head

William Furlow
Technology Editor

This Fill-up & Cementing Tool System combines technology from Halliburton and Frank's Intl in order to provide an option to the way the industry performs cementing operations on and offshore [57,657 bytes].

A process that combines technology from Halliburton and Frank's Intl may change the way the industry performs cementing operations both on and offshore. A tool developed by the two companies is said to enhance safety and increase efficiency in what has not always been the easiest of drilling tasks to manage.

Using the Franks FC-1 fill-up tool, casing is filled as each joint is lowered into the hole fluid can then be circulated around the casing. This fill-up tool has been integrated into the Fill-up & Cementing Tool System (Facts) the company has brought to market with Halliburton.

Once the casing string reaches the bottom of the hole, the operator switches from fill-up mode to circulating without the need for a swedge. The same system is used for cementing.

This is traditionally done using a plug container. The quick latch plug container is the fastest and safest way to do connecting and hookups, but it still takes time to rig up and has certain inherent dangers. The tool (cementing head) is a heavy piece of equipment. It is made up 5 ft to 50 ft off the rig floor. This means that workers have to be sent up into the derrick to do the rigging up and rigging down of this tool.

With the Facts unit, this head is eliminated. The entire process is streamlined, because cement can be conducted through the Facts tool without installing a cementing head. Installation of the system is completed on the rig floor, rather than in the derrick which reduces the safety risk.

The Facts can circulate and cement a well immediately after a casing reaches bottom, which saves an estimated 45 seconds per casing joint.

The entire Facts system is in place during fill-up, so that when it is time to circulate and then switch to cementing operations, all the operator has to do is unscrew the mule shoe from the end of the tool, install the plugs, hook up the cement iron and air lines for the ball drop assembly, and the tool is ready to cement. The tool is designed to be remotely operated, allowing the entire change-over from fill-up to cementing to be done on the rig floor.

Ball drop assembly

A key component to this new system is the ball drop assembly that controls the release of the bottom and top plugs. Two different sized balls are used in the ball drop assembly. A small ball to launch the bottom plug, and a larger ball that launches the top plug. The balls are stored in a pressure balanced tube controlled by air lines from the rig floor.

As air pressure is applied the mechanism in the ball-drop assembly moves up allowing the release of the smaller ball. This ball drops into a seat blocking the id in the lower plug. Once the pressure behind the plug reaches around 1,000 psi, the shear pins holding the plug in place break and the plug is launched.

In this design, it is impossible for the large ball to be released before the small ball, because of a failsafe mechanism in the ball-drop assembly that will not release the large ball while the small ball is still in place. Thus, an operator doesn't have to worry about dropping the top plug before the bottom plug is launched.

The bottom plug is dropped by remote control from the rig floor. Then the required amount of cement is pumped behind the lower plug. The operator then launches the top plug, via the remote control that moves the ball-drop mechanism down and releases the large ball. The ball lands on the top plug which is held in place by a collet mechanism.

Pressure behind the plug releases the collet and launches the plug, followed by the displacement fluid. When the bottom plug reaches the flow collar the rupture disk bursts, allowing the cement to circulate through the flow collar and into the annulus, driven by the to p plug and displacement fluid. Once the cement job is completed the Facts tool is removed.

Applications

Facts can be used on any wells where casing is brought back to surface. This means it is not applicable to subsea wells or liners. Facts can cement casing from 7 in. to 20 in. So far it has been field tested on 16 wells offshore, inland barges, and onshore.

The system offers a savings of about 45 seconds per casing joint. Additional time savings are realized in the transition period between fill-up and cementing and the rig up time for the plug containers. The combined time savings of the tool is estimated at two to four hours per job, depending on length and size of the casing string.