BAKER HUGHES - Drilling Fluids Reference Manual

FLUIDS ENVIRONMENTAL SERVICES
WASTE TRANSPORT AND DISPOSAL
When an operator decides to go to zero discharge, there are two main options for handling the waste,
either cuttings re-injection or skip and ship. Cuttings re-injection is a very effective disposal option
that fully complies with zero discharge to the surface environment. It is discussed later in this section.
When waste is transported from an offshore rig to the shore, there are several equipment options that
depend upon the infrastructure in the drilling area, the type of final disposal treatment and the
logistical limitations of the operator.
Skip & Ship
Skip & ship: use of cutting boxes that can be easily lifted between the rig and transport vessel and
from the vessel to shore on to trucks. These containers are built according to marine safety
specifications and provide an efficient means to transfer waste for long distances. Using sealed
containers has the following advantages:
a) The sealed containers are designed to enable them to be stacked on top of each other, thus
reducing deck space to store them.
b) The containers are easily handled by offshore cranes making them safer to handle than big
bags. The containers are designed to DNV standards and can be easily stacked.
c) Prevents both rain and sea water being incorporated into the waste stream.
d) Reducing water in the solids waste improves the efficiency of both thermal desorption and
incineration processes.
The skips or cutting boxes are usually
manufactured to hold 12 bbls (1.90 m 3 ) or 25
bbls (3.81 m 3 ).
Determining the number of cutting boxes
required to satisfy the waste transportation
demands of the operation is very important. Rigs
have very limited footprint available for storing
idle equipment and weight limitations per unit of
area. In addition, transport vessels are expensive
so an optimum use of their capacity and time is
important to reduce the waste management cost
of the project.
When estimating the number of boxes needed for each section, the following factors have to be taken
into account:
- Footage to be drilled in the section - Turnaround time for cutting boxes
- Hole size - Dry waste density
- Average footage per day - Drilling fluid density
- Skip capacity - Oil-water-ratio of the drilling fluid
- Filling up level of cutting boxes (percentage) - Base oil density
- Estimated liquid content in the waste
BAKER HUGHES DRILLING FLUIDS
REFERENCE MANUAL
REVISION 2006 14-26