The increasing environmental legislation surrounding the disposal of drill cuttings, especially in offshore environments, has led to the need for new, safer and more dependable technology. In many locations operators must collect drill cuttings offshore and transport them to shore for treatment and disposal. This has traditionally been done through the use of cuttings boxes or skips. These boxes are filled on the rig and then lifted with a crane down to the supply boat.
The number of crane lifts required to perform these operations can be very high, which significantly increases health, safety, and environmental risk. In addition, in inclement weather conditions, the cranes may not be able to operate, which can cause the drilling operations to cease. The number of boxes required can also take up considerable and often valuable deck space. One proposed solution has been to use bulk pneumatic silos to handle drill cuttings as is done with other bulk materials, such as barite and cement. However, traditional silos are not usually suitable, as the unique and highly variable physical properties of drill cuttings in many cases limit the ability to adequately discharge these tanks.
The HCB™ tank is a unique and patented product designed for the reliable discharge of bulk materials from pneumatic silos. It was originally designed for industrial bulk materials, ranging from dry powders such as fly ash and cement to high-moisture viscous materials such as sewage sludge. The HCB silo can be designed to store capacities from 20 cu. m to 2,000 cu. m and can be built in sizes ranging from 2-m diameter to 20-m diameter. The concept of using the HCB tank design for drilling cuttings (in conjunction with Halliburton’s SupaVac™ cuttings collection and pumping system) has been developed over a number of years with initial practical trials commencing in April 2005. More rigorous testing was performed from June 2005 through October 2005 when the system concept was proven to allow operators to handle drill cuttings pneumatically.
Traditionally, the challenge of discharging high-moisture and viscous materials from bulk silos was solved by having high-angle conical bottoms in pressure silos.While this approach has been proven to work in most cases, it creates limitations on the storage capacity of the tank in a set footprint.
