“We now have a triple-deck shale shaker, called a Multi-Sizer, that is capable of handling much higher flow volumes in a smaller area. It allows us to capture more solids and handle more mud in a smaller footprint. For example, instead of having six or eight drilling shale shakers, we have three or four of this new design that can do the same job.”
With the increase in underbalanced drilling and long, horizontal wells and tight gas formations needing greater stabilization, operators also are looking at what Mr Pierce called “designer solids,” in conjunction with a stress cage, to stabilize the wellbore. “We actually put a particular size of solids into the mud to plate out to the many fractures along the sides of the wellbore,” he explained.
“In this case, we don’t want the oilfield shale shakers to remove those solids, we want to save them, which ultimately reduces the cost,” he continued. “The triple-deck shaker is capable of selectively removing those solids, something we have not been able to do in the past. We remove these designer solids and then put them back into the mud. We put the mud over a very fine shaker screen and remove as much of the low-gravity solids as we can.” The mud is then put through a oilfield decanter centrifuge, where it is cleaned.
The process of selectively removing solids is increasingly being used for underbalanced drilling, Mr Pierce continued. “We de-weight the mud with a solid that is less dense than water but provides some viscosity. But we don’t want that removed either. It’s a matter of putting something into the mud that we want to keep in the mud, and then removing it with a shale shaker in such a way that we can capture it and put it back into the mud.”
The industry also has developed a new cuttings disposal technique for zero-discharge offshore areas. The mechanism uses positive pressure pneumatics that blow the cuttings into a storage area and then onto a boat, which then transports the cuttings to an onshore disposal facility. The system is used in place of the skip and ship method, where cuttings are placed in a cuttings box on the rig and moved by a crane until they are loaded onto a boat for transport.
“The new drilling fluids system saves time and is much safer because it eliminates handling steps and the use of the crane, which is one of the biggest causes of accidents in the industry,” Mr Geng said.
“If a rig is drilling very fast, the cuttings have to be stored in some type of storage mechanism,” he added. “But some of the newer rigs are being designed with an area to accommodate onboard treatment equipment.”
