BAKER HUGHES - Drilling Fluids Reference Manual

MECHANICAL SOLIDS CONTROL
MECHANICAL SOLIDS CONTROL
Chapter 10
Drilling fluid maintenance costs can decrease greatly when proper solids control techniques are
utilized. A drilling fluids engineer must be thoroughly knowledgeable of available solids control
techniques in order to maximize drilling fluid performance and minimize costs
DRILLING FLUIDS
Adverse effects caused by drilled solids account for a major portion of drilling fluid maintenance
expenditures. Drilled solids are the number one contaminant of all drilling fluids. Considering that
a 12¼ in. gauge hole drilled to 10,000 ft would result in 1,327,000 lb or more of drilled solids, the
above statement is not surprising. Overall drilling costs can also be severely affected by the
quantity of drilled solids incorporated into the system. These effects include the following:
• Increased drilling fluid maintenance costs.
• Greater difficulty in maintaining optimum rheological properties.
• Increased frequency/opportunity of differential sticking.
• Reduced penetration rate.
• Decreased bit life and increased rate of wear on pump parts.
• Increased circulating pressure losses, and consequently increased possibility of lost
circulation.
• Increased tendency for a well to swab on trips, possibly contributing to pressure control
problems.
A solids control program should consider the drilling fluid as well as the formations to be drilled
prior to selecting equipment for a particular operation. Care should be taken to operate the selected
equipment efficiently and in the correct sequence to prevent overloading any individual unit.
It would be desirable in most cases to remove all drilled solids. Although this is possible with the
use of chemical enhancement prior to separation, it is not always the most economical approach.
The goal of a solids control system is to achieve the balance between mechanical solids separation
and dilution that will result in drilled solids being maintained at an acceptable level with minimum
cost, while maintaining property specifications. This is achieved when the cost of the required
dilution fluid is at a minimum.
Classification of Solids
Solids can be classified into categories based on specific gravity and particle size.
BAKER HUGHES DRILLING FLUIDS
REVISION 2006 10-1
REFERENCE MANUAL