Honey Comb Base tank sweetens Halliburton’s offshore storage options

The task of disposing of drill cuttings during offshore operations has traditionally been hampered by the dual mandates of doing this quickly and with minimal impact to the environment. In response to these criteria, Halliburton's Baroid Fluid Services Division has introduced the Honey Comb Base (HCB) bulk cutting storage tank, which promises a safer and more efficient storage and disposal alternative to traditional cutting boxes.

In many offshore operating locations, operators are forced to collect drill cuttings and transport them to shore for treatment and disposal. This has traditionally been done by using bulky, cube-shaped cuttings boxes or skips, which are filled and stored on the drill rig, and then lifted with a crane to a supply boat for transport to shore.

According to Edward Porras, Technical Professional, and Jeff J. Miller, Scientific Advisor-Chemist, both with Baroid Fluid Services, traditional cuttings boxes have many design and safety challenges that the HCB tanks avoid.

"One major challenge we wanted to address focused on storing and transporting cuttings boxes," said Miller, who spoke at the Offshore Technology Conference (OTC), held 30 April-3 May 2007 in Houston, Texas, U.S.A. "In most offshore drilling operations, the number of cuttings boxes required takes up a great deal of deck space, which is at a premium."

Added Porras, "this large number of boxes usually means that stacking is required, which poses safety risks."

These boxes have to be transported off the rig with a crane, creating additional health, safety and environmental risks. "Transporting with a crane is not the most efficient operation," said Porras, "because in inclement weather with high wind and waves, the crane may not be able to operate. This would effectively shut down your drilling operation." With day rates for drilling rigs reaching upwards of several hundreds of thousands of dollars, drilling delays are not a pleasant thought for any operator.

"The HCB tanks, on the other hand, are patented storage products that discharge cuttings from one of six pneumatic outlets located around the outer edge at the base of the tank," Miller explained. "The tanks stay on the rig, and the cuttings are pumped out from the bottom of the tanks with no crane required." The fact that the tanks stay in place significantly reduces safety risks.

The tanks can be designed with storage capacities of between 20 cu m and 2,000 cu m, and can be built in sizes ranging from 2 m to 20 m in diameter. The tanks typically have much smaller footprints than conventional cuttings boxes, meaning that they can be more efficiently stored on the rig.

One of the most unique features, and the one that gives the tank its name, is the honey comb design of the tank bottom, which consists of six outlets situated near the outer edge of the tank rather than in the middle. "This feature allows the tank to be more completely drained than traditional rectangular-base boxes or pneumatic conical bottom storage tanks with a central opening," said Miller. "The older pneumatic tanks with drainage from the middle typically retain some residual cuttings after draining." The honey comb base design provides for 20% additional storage capacity over storage tanks with high angle conical bottoms, at the same cross-sectional footprint. This equates to only four HCB tanks being required for every five conical bottom tanks to store the same volume of cuttings.

The HCB tanks are coupled with Halliburton's SupaVac cuttings collection and pumping system, an air-operated long-distance pumping system that vacuums drill cuttings at a rate of up to 20 tons/hr and up to a distance of 490-650 ft (150-200 m). The speed with which the tanks can be drained, coupled with the fact that they do not have to be transported via crane, offer efficiency gains for the entire drilling process. "Some drilling operations may not be able to run at their top speed or capacity because of the transport delays in moving cuttings boxes to and from a vessel," said Porras. "Drilling operations using SupaVac and HCB tanks do not have that problem because the tanks have high transfer and drainage rates, and cranes have been completely taken out of the process."

The HCB tank caught the attention of OTC's Spotlight on New Technology Program Committee, who bestowed it with a 2007 Spotlight on New Technology Award. The award, one of fourteen handed out at this year's OTC, recognizes technologies that meet four criteria: new and innovative; proven full-scale application; broad interest and appeal for the industry; and significant benefit over existing technologies.

To learn more about Halliburton's Honey Comb Base bulk cuttings storage tank and where it has been successfully employed, please visit www.halliburton.com.